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LEST OF APPENDICES

APPENDIX 'A-' '• PORT CAPACITIES

• ' B f . A S S A U L T I N N O R T H A N D S O U T H S E I N E S E C T O R S

' C r A S S A U L T I N P A S D E C A L A I S

1n , : ASSAULT'IN COTENTIN PENINSUIA

f E ! ' C A P T U R E O F A L D E R N E Y

F'1 SUBSIDIARY ASSAULT TO CAPTURE HAVRE

' Gf NAVAL FORCES REQUIRED:

'H'1 SI-HPS AND LANDING CRAFT AVAILABLE

•• PROVISIONAL ORGANISATION. OF. NAVAL ASSAULT FORCES

•K1 ATTAINMENT OF NECESSARY AIR. SITUATION

<:j PLANNING DATA FOR IANDINCT CRAFT AND SHIPPING

,:M' RATE OF BUI LD-UP •

' N ' ' L A N D F O R C E S A V A I L A B L E .

' 0 ' ' : A I R B O R N E F O R C E ' S

f P ' ' ' R E S I S T A N C E G R O U P S

'0/ ENEMYNAVALFORC.ES

r R ' E N E M Y D E F E N C E S Y S T E M : ' '

r S ' G E R M A N F L A K D E F E N C E S

! T ' B E A C H E S

' U ' METEOROLOGICAL CONDITIONS

TV TOPOGRAPHY OF CAEN SECTOR

'•W1' ADMINISTRATIVE CONSIDERATIONS

' 'X1' METHODP. OF IMPROVING DISCHARGE FACILITIES. ' ON FRENCH COAST

APPENDIX: -'i' to COSSAC (43) 28

. OPERATION ' OVERLORD

ESTIMATE OF CAPACITI ES IN .TONS PER DAY • • AFTER CAPTURE- .OF'PORTS IN-AREAS DUNKERK-ROTTERDAM,

BOULOGNE-ANTWERP V. R0UEN-CAIAI3., '.CHERBOURG-DIEPPE,. NANTES--QAEN• (SEE HP )

1,» The' time-required ' to. open the ports is shown in days • and allows for•-

(a:) All necessary minesweeping* .

(b) Clearing of blockships to permit .the passage, at high water, of -craft and vessels drawing a minimum of ICO",.

2.. The tonnages for all ports in each sector have been totalled for purposes of comparison between sectors* In practice,, however;,. these totals cannot be related as the development of( each. • port is dependent on the day of ivs capture, which will vary -for each port within the sector* • Thus-one port for thirty days while another is only just opened or perhaps .not even captured;.. It is , therefore» -impracticable to ,^prqdteg;ra':;4^a%rport . : capacity per sector for any given time operation in which the; day of capture of each port can be estimated.-

3 • The ' figures -gi^e&:;i-n-- at-ta:ehed-- sheets are the estimates prepared. by Section, 'DD ?, of the RAP. staff» , . These .estimates are now under revision by- a committee set 'up- by the -principal Administrative Officers-, Interim reports indicate that the capacities-are likely to be increased- byan average-of riot less-than per--cent* - - -

SECTOR I DUNKIRK - ROTTERDAM (INCLUSIVE J

Daily tonnages throng Q ports Days 30 days 90 days

Ports required On after after to open opening opening 'opening

DUNKIRK 8 .1,800 1 3,000 4., 200 NIEUPORT 8 200 400 600 .

' OSTEND 8 500 1,000 1,500 ZEEBRUGGB 4 500 1,000 1,500 BRUGES _ 1,000 2,000 TERNEUZEN 3 500 1,000 1,500 ANTWERP 7 3,000 4,500 6,000 FLUSHING 2 500 1,000 2,000 ROTTERDAM and ) HOOK OF HOLLAND) 4 3,000 4,000 5,000

TOTIL i 10,000™""™' 16,900 2-ksJQQ ' SECTOR II

BOULOGNE - ANTWBRP (INCLUSIVE)

-^ailv tonnages through ports Days 30 days , 90 days

Ports required On • after i after to open opening opening opening

BOULOGNE 2 1,200 2,400 3,600 ' CALAIS 2 750 1,200 1,800 GRA.VELINES 14 400 600 800 DUNKIRK 8 1,800 3,000 4,200

: NIEUPORT 3 200 400 600 OSTEND 8 • • 500 1,000 1,500 ZEEBRUGGE 4 500 1,000 1,500 BRUGES „. . 1,000 2,000 TERNEUZEN 3 500 1,000 1,500 ANTWERP 7 3,000 4,500 .6,000

TOTAL 8,850 16,100 .23,500

• SECTOR- III . ROUEN - emus. (INCLUSIVE)

j ~ ~ 1 Daily tonnages throug! a ports 1

Days 30 days 90 days Ports ,... required On after after

to open opening opening opening . ROUEN 17 2,000 4,000 6,000. LE HAVRE. 5 2,000 3,000 5,000 EBIGAMP' 1 400 700 1,000 DIEPPE 4 6 00 1,200 1,850 TREPORT 3 400 600 800 ST VALERY-SUR-SOIvME 14 300 500 700 BOULOGNE 2 1,200 2,400 3,600 j CALAIS 2 750 1,200 1,800

TOTJiL 7,650 13,600 20,750

SECTOR IV

CHERBOURG- -' DIEPPE (IMG LUSIVE)

forts Days Daily tonnages through ports

forts , required to open

forts , required to open / On : •**.' 90 "lay a •

after opening opening opening

CHERBOURG ' 4 . 1,900 3,750 |- 5,000 BARFLEUR 14 200 300 600 ST VAAST 14 200 300 500, I8IGNY 7 200 200 200 COURSEULLES 14 200 400 600 PORT EN BESSIN 1 200 ! 400 400 • GRANDCAMP 14 200 i ! 200 200 CAEN « • / • ' ~ • i ! . 500 2,000 TROUVILLE 14 200 | [ 400 600 HONELEUR 7 500' . i i 750 1,000 ROUEN 17 2,000 4,000 6,000 SEINE ' ,

4,000 6,000

NORTH bank 14 800 . - -

• SEINE SOUTH bank 14 600 - -

IE HAVRE 5 2,000 ' 3?ooo 5,000 FECAMP 1 1 2f00 700 1,000

• DIEPPE .3 600 1,200 ' 1,850

T .0 T A I i 10,200 16,100 24,950'

SECTOR Y

NANTES - CAEN (INCLUSIVE)

Daily tonnages through ports

Ports Days 30 days 90 days required On after after to open opening opening opening

NANTES | 1 13 . 1,000 2,500 .4,000 ' ST NAZ.AIRE ! 7 - 1,000 2,000 LE. PQULIQUEN 14 200 400 .600 LE CROISIC 3 . 200 400 ; 600 LORIENT y ' 7 800 1,250 1,500 CONCARNEAU 1 300 400 500 LOCTUDY " 1 200 200 200 CROZON Beach 2 ; 500 500 500 RADE de BREST 16 600 900 1,000 BREST 3 1,500 2,250 2,750 ABERVRACIi 14 200 200 200 MORLAIX 14 250 500 600 ROSCOEF ' 7 200 400 ItOO PAIMPOL 14 • '200 300 430 BINIO 14 150 400 400 ST BRIEUC - - 500 600 ST MALO - - 750 .1,250

' GRANVILLE 7 430 600 :• 1,000 1 CHERBOURG .4 1,900 3,750 . 5,000 BARPLEUR 14 200 ' 300 600 ST .VAAST •14 200' 300 500

; ISIGNI 7 200 ; 200 200 ' COURSEULLES ' 14 200 400 600 PORT EN BESSIN 1 200 400 400 GRANDCAMP 14 200 200 200

• C«. ~ 500 2,000

T 0 T A L '••9,800.. 19,500 28,000

SECTOR VI

BORDEAUX TO BREST (INCLUSIVE)

Pott s

BORDEAUX 17 BLaXE' 17 TONiW- CHAKENTE) £ BOCEE^ORT j

O

LA ROCFRT d ,E 8 M PAT1T1TCE 2 LSS SABLES d'Olonne 8 NANTES : 13 ST KAZAIRE 7 LE POULIGUEN . ' 14-LE CROISIC 3 LORIEM1 7 CONCARNEAU 1 IOCTUDY' 1 OROZON BEACH 2 RADE DE'BREST 16 BREST 3

Days required, to open

T 0 T A L

Daily tonnages through ports

On opening

2,500 200

400

200 400 400

1,000 Nil 200

• 200 800 300 200 500 600

1,500

9,W)0.

30 days after

opening

4-,300 400

800

600 800

. 800 2,500 1,000

4-00.

400 1,250

400 200 500 900

2,250

17,500

90 days after

opening..

5,600 400

1,600

800 1,200 1,000 4., 000 2,000

600 600

1,500 500 200 500

1,000 2,750

24-, 250

SECTORS

DUNKIRK - ROTTEEDiM BOULOGNE - ANTWERP BDTJEN- - CALAIS CHERBOURG - DIEPPE tfANTES - CAEN BORDEAUX - BREST

COMPARISON OF TOTAL TONNAG SS IN EACH AREA

Daily-tonnages through ports

On 30 days 90 days opening aft er aft er

opening opening

10,000 16,900 24-, 300 8,850 16,100 23,500 7,650 ' 13,600 20,750

10,200 16,100 24-, 950 9,800 19,500- 28,000 9,4-00 17,500 24-, 250

AEgENDIX <B1 to COSSAW-i5T~28

OPERATION 'OVERLORD:

. .APPRECIATION- OF THE ASSAULT At© OCCUPATION OF k BRIDGEHEAD IN. "THS" NOm'H' Al©~30Urffi~SEINE "SECTORS ~

• • • • ' : 1 ^ : INTRODUCTION L \, , •

1, The NORTH SEINE sector" runs from the" River' SQMME to the-mouth .of the ' ' • SEINE;" the- SOUTH SEINE- from' the -SEINE estuary Westwards; to, the mouth of the' River ORNE. They include widely differing types of country, -but./from the tactical'.point' of,- view must, "be considered a single area, since the' requisite- ports 'are on "the SEINE and these "ports''-dannot be' worked until both banlcs of - th e . SEINE are held,- •

2. \ From the. NOEffl .sector • excellent roads offer the shortest routes to'PARIS.v Airfield facilities1 are good, and our fighter aircraft, -would :be. required to opel^ate at ranges from the' UNITED:. KINGDOM well within-their .capabilities: in the SO.UTH,:-SEINE. sector, however, our aircraft would be required'^ operate at estremg-range.. There::is ample sea-room for ^hipping. - 'The advantages of an occupation of the two sectors ate therefore clo-:,-r. " -'. •-

3,. LE HAVRE, which is strongly defended and whoso guns' cah? fire on;. the SOUTH" shore 'of. the SEINE as far ?EST as HOULGATE, has been fully appreciated by th?r ~

. enemy.-as baing. the key- to -both 'sectors. / .... . : ! :

4 « ' T h i s , a p p e n d i x ' h a s b e e n p r e p a r e d i n . o r d e r t o - c o n s i d e r . - , t h e ; i m p l i c a t i o n s ; b f a landing in the NORTH, and SOUTH SEINE sector's"With the object,'of: securing a lodge­ment •••area-in FRANCE capable of the .maintenance of about thirty divisions, which'

•might- subsequently be- reinforced- at the rate of'/three to five divisions" per'r'month.

" - - - G Q TSIDERATIONB ;

OWN FORCES . • ' VV:-

5. ; , - The forces available are f'ully .discussed, in Part: II of this "Appreciation. • r [ r , minimum* of'"twenty-six -and a maximum... of' thirty divisionstwo of ,-^aich. are air- -

• ;-r. -7bpwiQ,'.'.a're likeiy t'o': be available. : jfhese might' subsequently: be.reinf orced at the rate .of thiree' t'ofive-divisions.: per month1'" '•''.. : '. -vi-V- .' '':,J. /

6 . The landiiig • ships:Jand .craft .availablcyWill be sufficient to...life, three:' • assault divisions, with "overheads", and the' equivalent: of two divisions omitting

"overheads" at light scales in the immediate follow-up. It has. been assumed. that . enough, merchant shipping will be available to lift two further divisions with,

"overheads" . • ;

• ' 7 # : . I t . . . i s e s t i m a t e d t h a t t h e t r a n s p o r t a i r c r a f t a v a i l a b l e w i l l o n l y b e s u f f i c -..... .. Jient to transport' two thirds of .one airborne ''division in one' lift-. ' .

TOPOGRaPHY OF THE AREAS - GENERAL

NORTH SEINE , :

8. Prom LE HAVRE.Northwards and Nprth-Eustwards to AULT there is a line of precipitous chalk cliffs, which are at least-200 feet highyifi most places. These cliffs, apart frcm odd scramble . landingsj - are 'unsertfcea&i^ they are interrup­ted by a limited number of isolated beaches, where rivers and streams run down to the sea. There are some thirty-five beaches in all, but of these only four are ov^r 1,000 yards and nine over 800 yards in length. See Sketch 'SB I'. They are often backed by towns or villages. •

' •• • ' '' ' ' . ' ' ' " .....

9. . The distances between the four beaches of over 1,000 yards in length ibe: -' . . . . . . , ' • - * - ' " ' ' • . ' ' . •

ST iiDDRESSE to FECAMP - approximately • 27.miles FECAMP to DIEPPE - Approximately 40 mile,s. • DIEPPE to MERS-LES^BAINS - approximately 18 ndlos.

It should be noted that ST ADDiffiSSE.'beach lies directly NORTH o f the Korthorh breakwater of the Port of, .HAVRE,The steep gradients of . these beaches make them particularly suitable for beaching craft, but the exit capacities are relatively small, : •

10. Fr om AULT to the ;mouth of the River SOl/QaE--the coastline yisf low and.sandy with occasional banks of shingle, Behind this length of .beach/there is IqvT-lying marshy ground which widens towards the mouth of the River SOIvfME. It is intersect­ed by many streams and ditches. The Eastern half of the beach is flat and unfav­ourable for landing, though the Western half is, from the naval point of view, very favourable. -:•

11. ; Behind the whole sector, the country inland is mainly arable,-, suitable for airfield development and provides good going for AFVs; routes inland run mainly towards PARIS, end provide considerable cover for movement and dispersal.

SOUTH SEINE

12. From the mouth of the River SEINE Westwards to TR0UVILLE, the coastline is formed by' alternating stretches of low.cliffs and small sandy beaches. Fran TR0WILLE to .River 0RNE the coastline is lot/ and sandy, except for a short stretch of sandstone cliffs, in the centre. Near the river estuaries the beach becomes very flat and muddy. There are sea walls opposite the coast towns throughout this sector. The beaches are long and have a large capacity. . ..

DEFENCES

NORTH SEINE :•"

13. Gaps in the cliff formations are defended by guns, wire, obstacles, of all kinds and mines, to an extent proportionate to the tactical importance of the towns or villages at these openings. Important points such as DIEPPE and LE HAVRE have in addition an all-round defensive system inland; Certain gaps, in the cliffs, where there are river mouths, have been inundated to prevent ingress.

14, LE HAVRE and the neighbouring airfield at 0CTEVILLE are defended by heavy concentrations of artillery,,including a number of AA guns sited in an anti-shipping role. To guard against attack from landward a defensive position has been constructed on the general line HiiRFLEUR - River LEZtiRDE — FONTAINE Lux MALLET— 0CTEVTLLE, The River IjEZARIHDhas been artificially flooded for 2,000 yards inland from H/iRFIiBDK.

15* Ares of fxire from NORTH and SOUTH sectors are shown at Sketch, 'SB II1. They extend- across the River SEINE as far as HOtiMAKSi • It should be noted "that,

; these arcs x'er, resent• extrbivm ranges. : /;:y .'-7-'- '

•• !Dhe'port -of 1^'liWEE. is'booiiied and' probably rdned. No evidence exists about similar obstacles-;iii the SEINEj.\ '.'-aiary, • ; :

- SOUTH SEINE

17» :: Gum. concentratiohsv ^though much less dense than ait EE :Hi^Iffi,:': are: strongest i n t h e V I E L E R V I L L E a r e a , . S O U T H ' o f H O U L G A T E a n d a t O U I S T R E H A M , - ' ' A s m a l l n u m b e r o f . guns ' froia VILDEVILIiE cah fireon liE HiWRE, and interlocking arcs-'' fFbm.*BOKEfi • -arid.

.SOUTH make'any approach to the- mouth of the SEINE a matter of' extreme;hazard,

18. It is therefore/apparent that-the neutralisation or capture of LE HAVRE is- essential before V'lMding 6ari' take: place'-on the SOUTH SEINE*- and that operat-i<on pr-:'developmeht of LE ':HAVRE:,-; -and the- improvisation' of unioading-:faci;lit.-ies in vthe: ;SEiro Estuary,; 0.r,e impractic'able until the SCj'IH bank of the river has been captured. •'' -- - :r;: :v'7 - " • rV:;rv.:L'Vi--•

AIREIEIJ3 FACILITIES - GAP. * .;' \ ' Vv,/":' V. •

19. ' -The NORTH SEINE .sector is' within range- of ^ large .ttumbe^ : of enemy main air­fields fbet^essn AMIENS-and'EVREUX..^ .The SOUTH SEINE.'sector' is'within'range of a Targe number of airfields in the: EVliEUX area, Ify.therefore, an-attack7is launch­ed/ against both; the SEINE- sectors'.,the enen^-'would be able to. operate fighters from a large number of airfields'- at comparatively short range, Yi/here.&s our . . fighters would'be required to '.afford fighter- protection -to. our. assault', forces ex­tending over a very wide front, Thus, in addition to seribus tactical disadvant­ages, so much of our fighter strength would'be confined to this, purely defensive role that offensive operations, both fighter and boniber-:> -would; be, severely cur­tailed, -

SUITABILITY OF .AREAS FOR LARGE^SC^IjE: QPSB^CIOMS

' NORTH'SEINE ,

2Q» It will have been noted. that-- possible landing beaches for large-scale assaults are; few iri' number, and are widely separated, In addition, with the exception of the,be&ch at ST ADDIESSE, • which is -immediately covered by all .the

^ d e f e i J u S e s / ' O f J E d t l V K E v ^ t i h i e y l i e a t b o n s . i d e r a ' b l e . d i s t a n c - e s f r o m t h i s t o w n . - - - •

21, • ^Mare^er^ •LeiMs- to.' the. defence- of" bh& ? •:narrcw-opeiB^B ;in th& cliffs by mines ^wirev -'ffiti-tank/dito.hes -and walls > arid . md^e'irdportari^ •••fcwis have all-round. .defences," Both sec tors;'hay 6; artillery sited to cover all beaches in proportion to-their, importance and vuinefability. Further delays in development Mil": be imposed "by. energy fire>_:by blocksand dsaiiagd caused by our air tod sea bombardment'and by''the ; difficulties of. clearing beach exits, • The enemy fire may be to some extent neutralised by previous air. bombardment but -with the e^e'ept'fen "of*<IjE H/WBE itself ^" the-':defences do not<, owing, to their ; dispersion, offer good, targets^ nor can the. probable: extent of neutralisation yet be assessed. on-the. data -available,,. \

22* . .From the 'leng^h'-'of'b/eabhes: -available.* the: si^e- of.'the'•.assault'if orces- will' ' be severely restricted,. On.' the assumption' that- a battalion;would^. from, the military; point rof yiew/ need;;&- frontage of:; some ;5-0ffryards' t o 800 yards - on which ••fed-' Goirrf- - out ^ an assstulty • few assaults ; oould- exceed-such a. strength,-^ ;

23#. The fact , that suitable-'beaches are ' widely separated means that mutual support between assault forces landed will be difficult* if'not-impossible^ at any rate in the. early stages/

24.. It seems unlikely that the small assault forces able to operate will be of sufficient size to overcome the well-sited defences in the area in time for the arrival of the large number of follow-up forces required to be landed in an operation of this magnitude, particularly in'view of the fact that available exits and routes inland will have to be cleared of rubble caused by our own bombs,

25. Furthermore the riwer lines, generally speaking, run at right angles to the coastline. This means that no natural defence lines exist on which the assault forces can establish themselves, and it makes lateral movement between our forces difficult.- On the other hand, these rivers would not hinder GERMAN counter attacking formations arriving from the interior of FRANCE.

26. It is concluded therefore that an initial assault in the area of NORTH SEINE, on the scale envisaged in Operation 'OVEEIXDRD', would have little chance of success owing to the dispersion of effort dictated-by topography, the lack of mutual support between assault forces landed and the absence of defensive perimeters round the beaches which could be attacked,

SOUTH SEINE '

27. Although suitable beaches exist for an assault in the sector EAST of the River ORNE to the River SEINE, these beaches could not be attacked until' the defences of IE HAVRE were put out of action. Although "softening" of the defences may be possible on a large scale, it would be unwise to assume that these beaches could be assaulted until, at any rate, the defences of LE HAVRE were being attack­ed from landward. As has been shown above, there is little chance of this'being a practicable possibility. .. ; ' . "

ENS.H R/.TE OF BUILD-UP

28. The GERMAN plan to defeat invasion is based on the holding of the coastline at all costs. Mobile reserves have reinforcement roles in each sector, and it is thought that, as the threat to any one sector becomes apparent, they mil be con­centrated in forward areas within striking distance of the coast. This will enable the G-ZRito bring their counter attack forces into action in the early stages in support of their coastal divisions.

29, The road and rail systems into the NORTH and SOUTH SEINE sectors favour this course of action, and any mobile reserves which might be available to them would be able to reinforce either area quickly. To counteract this advantage it would be essential to create a threat or diversion in some other area of the coastline to delay the maximum number of divisions. Further, it may be possible, by air action against communications, to reduce the flexibility oi' movement of reserves, thereby forcing the GERMANS to coranit a proportion of their reserves to specific sectors. This would reduce the total force which they could con­centrate quickly in any one sector.

JO, In addition it might be possible to reduce the fighting efficiency of formations by night banbing in their rest areas; and to interfere with their movement by air action. The effect of this air action cannot accurately assessed. It is unlikely to impose much delay on formations moving by road, but it would probably cause some delay to divisions moving by rail,

31» Another possibility is the use of airborne forces to delay the enenqy's advance, A prior claim on them in the NORTH SEINE might, however, be the capture of the airfield at OCTEVILLS anc^/or cecrtain batteries .at I*E HAVRE; and the terrain is not such, in either sector, as to lend itself readily to the holding of nodal points.

a 1: V . ' . 5 * : " ' : . • • • . . • • . v •

32, ' . There is, In addition^'- the action- \7hach-iiiigkt-.be • talcen" by:r esistance;"groups^. This, again/, cannot be accurately 'ass.^ss^ci ^d it 'is felt that - whatever 'delaying • actxpn-theygdo .treated .a ;::a:'bonus#-.': ' v ' .' -. v :

33* ; Toa:sum;upr.' &ere: jLs;:.littl^^^^ addition to- the division^ holding ; . t h e . . e o a s t a l i - s e c t d r s ^ ' t h q . : b o a b l e " t o r e i n f o r e , e r , e i t h e r o r - b o t h s e c t o r s

' r^pxj^y "with:such reserves: as they might, have - at"' their disposal, ^ these, .divisions ., in reserve riiight? however, have -been reduced in ef fipiendy^by• •••our' air . action.,.

• -GOHSTO^^ EiiiLi)-up ••••: •

34 • ;,The difficulties' of the initial1 •asgclult''ii$ ithes :NOlf£H and' SOUTH SISX3>IE: . ' sectors have;^^ stressed..;; If , howevbr,, the :assaiilts;""were '-sifocessful^

- ''tKe .laeatidn$;;;:of'.the-vbeaches'which must .-.be/assaulted would again-"impose the con~ . t.V^/litioriitha't::a^' of • .,the subsequent forces landed must be strung '.out on. a long front,

"" They would be separated from each other by the River SEINE/ a formidable obstacle, would be difficult to control,, would .no,t ;'bfe. mutually supporting, and. would be liable 'to-defeat in detail by. superior'', enemy reinf ore orient s.^. ^,

STRATEGII'C^b;gQKSICTiifeTIQMS '' V: ; 4 .v" V : ' ; /

•35a As: r''e'liaade' emmot. be placed 'on maintenance- through the beaches, for -a Ipixg.'. 'period.,'\it' :will be, 'essential to capture' the, ports,of LE. ,,-JiQtJIlN- aq.d H0HPLEI3R to maintain a; total force ashore of thirty • div'isidhs, a. -V:.;a.•'

• 36. ' Wo-^landiiig -posaiblo-.in the SDU^ until the defences' of, • :;•• LE HAVE®-. hOT'@-:bfeen neutralised,.Equally,; it i:s: impi?acticable. to' operate .the port .

. of 'M&R&'-yt&t ill' guns oh. the VSOUTH. sector- mthln .range, of it have been . neutralised, or captured#.. ' .. ' >.;V • " • - .; •

37#. J.V; IE defences;, ; cannot: be captured by''direct: -.' assault;c:fro^ nor .is.v-it-' comidered that :air bo^arclment alonec can: neutrals ise it; vthere/aire:-no'beaches -immediately to the"NORTH• dn4' which, can be used. • for a landward ' assault,*--.TE0-:'%xhg'l:e' 'beach . of -;'ST'--jlU)DRSSSE in,. .LE Hi^RE; itself is., heavily;xlefehded;blocked, It...must ••.therefore- be ta3^n .by land -f orces which; . have come In. <3n.:som£aof ^the^;b^aches ;.sho^n-^.:Sketch.,1;SgvT,,•- possibly- in conjunction,

w i t h a i r b o r n e f o r c e s : a n d / o r c o m m a n d o l a n d i n g s •

38# / F orces : landirig between ETRIM and ST V*J^RY~sm~SOMffi would therefore •, have a double, task:- •' . .

. (a)' to advance to capture LE HiiVEE,

(b) to form a flank to. protect the bridgehead, and to Isolate the HAVRE Peninsula*

39, If the prospective, length of the bridgehead perimeter to be- protected,, and the .distance of the approach-imrch'' to='LE HAVRE., were reduced by confining the landings to thev more westerly beaches^ the assault and follow-up forces would- be more than proportionately reduced<, since the -beaches' grow progressively less favourable Vi/EST of DIEPPE and cease entirely at ETRE'LlTThis., excludes the • possibility of holdings during the. .very ecirly stages, a vex^/ small protective flank, such as is provided by the River lE.^iEDE •imocU-ately .EilST of LE ILiVRE.

40# " Any attack on LE HAVRE would be under fire' from guns on the SOUTH: shores, and, unless a simultaneous attack-could be mounted against the SOUTH sector, the -enemy would be sufficiently aware" of 'the' situation to reinforce the. HONFLE,OR -OUISTREEKM beaches in-preparation for our landing..

\ * , -.« • '•*

41, The ;tvo landings would then be split by the River SEINE; there are no bridges until RCTJEN, seventy^eight aailes upstream^ although it is only forty-six nilos by road from HONFLEUR, and fifiy^four- miles from IE ;&'iVRi2, The river is unsuitable' for bridging operations owing to its width, rise and fall of tide, strong current and, tidal bore. Mutual support would therefore be most difficult until after the capture of ROUEN.

42, While the splitting of our own forces would hove the effect of splitting the energy counter attack forces, his pool of mobile! reserves would be positioned in the general areas North-East and South-West of the River SHINE for just such a contingency; and his forces could achieve considerable superiority during the early stages. This would bo accentuated by the fact that the beaches would compel us to a number of comparatively small, isolated landings, with consequent difficulty of control, •

' ' ' CONCLUSION !

The NORTH and SOUTH SEINE areas.together offer considerable advantages in sufficient port capacity, including deep water ports^ for the maintenance' of the vhole force; in short and good routes to E**RIS, and in suitable country for •; ? irf ield development, : ; - :

44. The main disadvantage which they present is the fact that, on D day, 1orces landing on scattered beaches on the NORTH sector might be subjected to inrnediate counter attack by reserve formations, and consequently to defeat in etail. In addition, the River SEINE necessitates the splitting of our forces, vithout any prospect of effecting an early junction,

1-5. From the air point of view, an assault in this area on such a wide front ./ould give such a tactical advantage to the enemy that, even with the large air forces available to us, adequate air cover combined with offensive air action oould not be effected, "unless the enemy fighter f orce j s adequately reduced,

'f6, It is, therefore," concluded that an operation which must be launched on such a wide front is unsound from a militoxy and air point of view, so long as the GERMANS are in a position to launch counter attacks in ary . strength and have adequate fighter forces, . '

PRINCIPAL B€ACH-ES - NORTH S£IN£ SECTOR

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MERS- LES- BAIN S(208) J V-EUL-ETTES 227

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-• APPENDIX fG'-,t

OPERATI ON ' OVERLQRD

ASSAULT: AW', QOQUR&EION '

; •'•• - "" " J1.\TTRQDtTCTI0N """. '

1 » T h e ^ 0 , i \ L A I S o f f e r s m a n y - o b v i o u s a d v a n t a g e s a s a n area in jrhich' id.|'ef?eGl:a.a/^ip5.gem.enV .op the Continent, Its proximity to 'our coasts 'ensures "the-m^^ aircraft .operating,: uild<gr the*mbSt;"^youra35le .conditions^ ^The-;short sea routes would, provide a 'rapid".'tupi: rbund.of crafty am shipping and would greatly • 'lighteh''"t^e'^u^eAVpf" ni-vaI',.espiQr<:: aixl:.prote<?ti$iv In addition, '• the "for, ease-, fuad .efficiency.• ;of--signal, ;Comia~ uaic&tibhs," :'a^"wduld"facilxtat'6' the mainteiiance of supplies,* ; For example^ the seaborne maintenance lift'could be reduced by the install­a t i o n _ o f . t h e H A I S ^ . q a b l e . t o . c a r r y p e t r o l , - . ; • • . • •

' ;2» J:Moreov-er?; "the. area, offers, poss

;in the.fprai^ of a. thros't " o dmirohicataon"'^

abilities of strategic development .across the' enemyylines of

.3*. On, the,,other ,hand?., and. for these ..very reasons;,'.the PAS D,B;; CALAIS is the most strpngly :lcfendo'I area of the ®ENOH :poastf artS tkfe- piwt 'coastal''4^f^^, system4. > .... r;: .•/•;.;••

> 4 . ; l a v i g W ; o f , t h e . . o b v i o u s , a d y a n t a g o s , ' t h i s A p p e n d i x . h a s . t i e e ? * . , > • .prepared,,.to'considerthe .iinplications of. a landing in the PAS DE .CALAIS' with the object of secux'ing a .lodgement .area'.in^MANOE, capable, of ;t']:ie maintenance of about: thirty divisions and of. further development to

,niaintaih..'.subs.egu.ent. rpinf9r3CT;ent:n.,.^t ^threev.;to;- five divisions per month,.. '1 ;,'.w,.,. ... >. •' ,.; '" ..rc-

.0 0 • \"3 u 3" i ? i q n s

OW-FORGE'S';

5. ,.'-; ;' ; The fdree's ^vMlabie'1 are 'fiil'ly discussed in Pair.t. II of this Appreciation* A minimum df twenty-six and a maximum of thirty divi­sions, two of •which, are • airborne, are likely to be ^ available. ., These.

reinforced .at the rate of three .to five divisiOhs might subsequently be per month. „ . ... .>;•

6» ; The i:ahdihg;''^hips and draft available, will .bp. sufficient.,to lift three' asskult divisions', with, "overhead'sand "t'he .equivalent of

'-•irw'©\.diMsi,b^7'":®i^'^^S: ''overheads'1,, at light scales in. the immediate. •: f ollow^iip «• '• It' 'has "been assumed* that"' enough merchant; shipping; will be available^ to'--; lift two •ftorther*' divisions' 'with'""

7« It is estimated that the transport aircraft available will only ,be\ sufficient to" transport two -thirds of one - airborne . division:' An one.lift.

6, The air forces available will toe considerably larger than \ t t lose available to the GERMANS; and will be operating under optimum condit ions.

capacities and their effect on operations

9. The weight of the assault and rate of build up of this force in the early stages will depend on the capacities of the beaches in the PAS DE CALAIS. An exhaustive study has been made of the beaches and it has been -foC^d-that there are only four beaches suitable for the landing of assault divisions. These beaches lie astride BOULOGNE, between CAP GRIS NE2 and the River CANCHE. ,

10. The- theoretical capacity of these beaches is some 6,000 vehicles on D day, i.e. about two assault divisions with "overheads". This estimate is based on the capacity of the exits and assumes they are fed to capacity by craft and shipping. It takes no account of obstacles or enemy inter­ference. .

11. 'The PAS -DE CALAIS is, however, the most heavily defended sector on the coast of PRANCE. The area.of assault is likely to be held by two coastal divisions, one NORTH of, and one SOUTH of BOULOGNE. The beaches and their exits are blocked by numerous obstacles - barbed wirpj elements 'C', concrete'walls, minefields, anti-tank ditches,- etc. Further delays

'•ih;development will be imposed by. enemy fire; . by. blqpks . and,damage caused by our air or,sea bombardment; and by the difficulties of making road diversions in the sand dune areas. • ...

•12, The enemy fire may to some extent be neutralised'by previous air bombardment; but the extent cannot yet be assessed on the data avail­able. Nor can we yet say whether prolonged air bombardment will destroy the obstacles,, It is certain that bombardment of built-up areas will increase rather than diminish the difficulties of clearing the exits.

13» ' In vievr of these, limitations it ..is considered that the practical capacity'of the- beaches in the early stages cannot exceed, at most, 50 per

: cent of the theoretical capacity; and that the assault force must be limited to not more than one division as at present conceived. , Even this limited force comprises 3*000 vehicles including essential •"overheads".

14. After the initial assault and follow-up, from about D plus 2 onwards, the capacities of the beaches are such that about one and one third divisions could be landed per day.

15» • • It will be apparent, therefore, that the strength of the assault arid the rate of build up of our forces in the early stages will be limited by thd beach capacity, as reduced by the delays and disorganisation caused by enemy defences and resistance., 'Softening' of the defences may be •carried'out on a very heavy scale; but until there is further evidence of the effect of air assault on positions of great strength held by GERMAN' forces, it would be unwise to assume that these beach capacities could be increased.

ENEfaff RATE OF BUILD-UP '

16. The GERMAN plan to defeat invasion is understood to be based on the holding of the coastline at all costs. Mobile reserves.have reinforce­ment roles in each sector; and it is thought that, as the' threat to any one sector becomes apparent, they will be concentrated in forward areas within striking distance of the coast. This will enable the GERMANS to bring their counter attack forces into action in the early stages in support of the coastal divisions.

' * The road and rail communications to the PAS DE CALAIS area from the rest of FRANCE are excellent] and there is no doubt; that plans for movement of reserves will have been carefully elaborated.

18, . Some delay can-be imposed.on, the engmyl-s'' rate.;!qf'.;;r ii3tf9rc; ment by air action, arid, resistance groups,? ,buf the• ainount: 1$• di cv tvtcfev8iss©s » It: is1 unlikely that much- delay wil1,:/T5.e; imposed : on divisions' moving by road -but: a day; lor"twols delay'. ould ' probably beimposed on divisions, moving by Faili*.- In addition the'fighting efficiency of enosy reinforcements

; isrhether moving. by road or rail is* bound to be reduced by intensive 4$-J- &nd. night bombing. : - . . ' ; '

- 1$. rthei:' (lelay:::might-be imposed, on- the enemy b ;-!the us'e of air-: borne- forces. ; .""in .'the, PASuBE CALAIS ;' h yer,,;; ..the iriature ;of., t% country . and the-numerous roads would: make';it"'impossible, for -us to eiaq yff cient nodal points or obstacles for this form of attack t'o have any appireciable.

COMPARISON OF FORCES . V ,; , . .- v::;' .-J..7 ,"-;

, 2 * 0 . ' ' I t . wil l ' b e Been., : therefore, that the odds are- heavily' against • !" the suecess of our 4nit aIc'a3Sa 4i ':'-!Largei|:r.due;,tQ..''thS''':ph Biciai factors, being--weighted'''against us,,:;;-! :Th6.!-very•l.imi,ied and heavily defended beaches will. limit our ''.assault- to 'one division on D day, • • Against • this the,- 3;;

. Gi IANS' have not. - only the .tvvo-existing divisions holding the coastal sector but wptald from5 D day onwards be able to achieve a very rapid rate of reinforcement, owing to the fact that.,.the, PAS DE CALAIS is the pivot of the GERMAN defensive layout. • Effori l'elay1-- the moves of qnemy-.reserves, .:.: . are likely to be less effective than.elsewhere owing to the. geographical position of the PAS DE CALAIS and' the'topography;;,.within it# ,

. 21,. ... r;:- ¥6' ebrtciude therefore that so long as the. GERMANS are able to, < reinforce the PAS DE CALAIS rapidly our assault is unlikeiy. to succeed#; '. Even though it were possible-by. air bomb.ardment to soften the'boastal 4e >::

fences ,h:the' physical ;diffic3uiti©5: of'the benches would still limit the Size of: our1.aissault forces and:- slow' down* the rate of our build up, while, it would be-'diffittuit" for. us to retard appreciably.'the moves of : the G-ERMAN-reserves. •

.. ... . •; •

SIRA.TEGICfjj' CONSIDERATIONS:

,22. : As suiting'that it were possible, , in .spit0,;::of: these .difficulties,: to obtain a lodgement, • in the.PAS DE CALAIS, ;the iivisediate capture, of : : r ' . i : r r

P,P..3?ts- wQmM :bed6me',*imperati as the beaches .arq/completely 'exposed, to "vtox Prevailing winds, raid maintenance- Across- .them, is liable to interruption

inroad weather.' ' .... , .. ,. - ::o :

23. . rTwo ports aire geographically within ' the PAS DE CALAIS •?;'BOULOGNE and CALAIS. It is considered that the two. .ports; to 'ther-'vbould, after. :' three months, nc.intc.in a r.iinimir;': of nine divisions. The pOri .'capacity:. ' :'' is under investigatipn'.!ahd,;.ffiight:',be supplemen.ted;by;means\6f HAIS-.Gable,' " beach maintenance;'' within, toiNaakwat'e .to • maintain perhaps twelve divisions; ,v .:. y.ov.rV-[•• •

2fn, In order to maintain the thirty divisions available, it will be necessary to extend the bridgehead either Eastwards or Westwards to include further ports.

25, An extension Eastwards would not give, us the requisite capacity till we had taken all the ports up to and including'ANTWERP, Operations to achieve this, would entail an advance across the front of the GERMAN armies and across numerous river obstacles/or inundated areas and would involve long and exposed lines of communication. The force required to

SliSaiS feo thfjAS D?cffiSl°portI. llneS °f «« not Ue

4. (

26. Expansion of the bridgehead South-Westwards would.require an even longer route before sufficient ports became available, as it would be necessary to include HAVRE and ROUEN. An advance in this direction would again involve a long exposed flank, and would entail the crossing of. numerous water obstacles.

27. Apart from the question of the.seizure of additional ports, the .very holding of the bridgehead in the PAS DE CALAIS itself is a formidable problem. Y/hile natural flanks might be found in the River CANGHE in the South and the CALAIS Polderlands in the EAST, at no stage in the exploita­tions inland does the topography of the area offer any.natural defensive positions which might be held until numerical parity with, t-the. enemy is achieved, ' •'

28. Strategically, therefore, the PAS DE CALAIS has the disadvantages, that it does not offer sufficient port capacity to maintain "the force required; that it does not offer possibilities of expansion to secure. v

additional ports within the strategic capacity of the forces available; and that it does not offer suitable natural defensive positions which would ensure the defence of the initial bridgehead for its exploitation ty stages,

CONCLUSIONS. "

29. In spite of the obvious advantages of the PAS DE CALAIS provided . by its proximity to our coasts, it is'clear that it is.an unsuitable area; in which to atteirrot cur initial lodgement on the Continent.

30. • Not only does the strength of the defences danand a weight of assault which the restricted capacity of the beaches Cannot..admit, but the restrictions imposed'by th<p beaOb.es do not allow a rapid build up,

31. /.Further, even if assault were practicable, the. geography of the area does not. permit of- the capture of sufficient, ports to maintain the force, and the terrain does not allow of the defence and exploitation of the bridgehead by the occupation of successive natural obstacles, , r-/•

32. While these conditions might be somewhat, modified, by factors, which cannot be accurately assessed - the effect of intensive air bombardment, the action of resistance groups, 'o'rr'that -improvisation in: maintenance organisa­tion which the prospect of an early and-decisive battle might justify. -the cumulative weight of evidence shows that, under conditions as known at present, the operation is militarily unsound,- /

33. These conclusions are, however, without prejudice to the importance of the PAS DE CALAIS ferea as an objective, for feihts and diversions, or to its suitability for a large scale landing should.any ; . major changes take place irt-the' CSiKMAN capacity t'o defend, it.

AEgENDIX^D'

''AHTOIfllEIOIT 0? THE ASSAULT MP OCCUPATION -."I' 5 $ W A F E - T A A B S R C C T K . P I I S N S U L A ' : ' • ; • • :

• ' _ 'INTRODUCTION ' '

1. •• The purpose of this appreciation. is .to detemine the.if.easilDility of the assault upon and•^he'-opc^ bri-cwhead'' on the CQTElfeN Peninsula in order to estbBHshia-lodgenBnt;;dn-theoNo^%TOs't cb'ast of FRJU^S' which mil enable us to gain sufficient deep 'water ports forJ'"the accoroodatidn of the landing of large forces from the US. ' . •. ^

.&r.L:;r..ixrr,:;., CONSIDERATIONS'

• General • • . . •;. '

2. In.; order te fUlfi-1, the object-of the .operati6n3 the-ifpliowing requirements must be ;-"me.t.:~ .., " ' ... ; !

(a,) The initial assault .must-taku place:wi'thin- the'range- of*.' effective fighte^^eoVeribjj-air cra'iH;-'6^

• (b:),;-'-There .must be' suffIci'entliaiii\Lxej-ds. or. readily -developed;,airfield sites to preside bases fp„r pur tactical, sir' forces- On the Continent.,

(c) ; :.There must be adequate ports' api ^elt^e^-^^fcers to .supply and maintain' about.- thirty divisions -from the UK,- •'

4d)----There must be sufficient'space with controlling .terrain features to '3-ct-: ...enable ''our--forces,to..secure the lodgement'-1 area and to "facilitate

; jfe^re;^^ratj.:pas.^.?. tM"Capti^v.x>f...the deep-water' ports required to , . accommodate the • landihg-'-bfiv.large- forces-frcs. the US»V. , •

--'''r Terrain -

3». '-. k; The, ;COTEOTIN--Peninsui'a'''\is -generally- low and- enclosed,cut!by many -sunken £pads,.;-:graxii^ c.,weI"l^-Yfooded country at the tip. just SOUTH of CifEKBOUE.G-^to jow marshland.'cd'untx^-iat->tke base® It -offers poor" facilities, in general»---•• for kirfield.K.siteso. ' The' LlSsAIr-C.AMlNTAJjr area,' at the base of the peninsula, is -oii2y\1i^en%^fd^/&i:^es -i»ide, manyVparts, o-f; which -can be flooded. This constitutes a defile whichJm'j^r -be'-defendedby a: relatively small number of troops, and offers a.position mhe're mr.,c-overirig forces .can effectively delay the enemy rate of. reinforcements The beaches at;'4h£ '101^ are small and steep 'Wi'th' -some of f-lying. rocks and only a1 liiKi-ted number of exits. The only suitable i.dsault:- beaches- bri-the".Western side of the Pe.ninsul-6...are those.in the'vicinity of VATCCLL®^-,SCIOTOT,v and,-'B4;UBIGlff'j Which- are.moderately steep' and- havo - sufficient exi%S,\.butvVd3i-Ch ' are unshelt ered' from'iyesterly .vi'ridsv" •• ,.-Qn-the ,-EAST coast there a^eN.6j.QQQl.yards of"' fine sand^ 'be aehypwhi-ch ,a?e sheltered::,frem'.'prevailing'?fester^ wind's,:.- and, to some 'extent,: frbjn''J/aM;e.rly wihds»':' '• The/ exits to the Eastern beaches are limited ;by water i-grpiihcl" and to. .some'/.extent- by. sea v/alls.

Enemy- .. - ..••• ',''' ;•, ...

; Based on the Intelligence estimate as of 1st June, 1945/' the COTEMTIN Peninsula, is held Lby .a defensive division of two. regiments- along the NORTH and EAST coasts. . In addition, there are some centrally located units,which 'constitute .'^lie'" equivalent of" a re serve;-regiments'In-, the, event, of a serious ' threat of: invasion, it ds-- probable' :thativ in- addition, tlie GERMANS would , - : maintain one di^^on.dn-re§e:i*ve in: the.CCTipilN; Peninsula, . . ... . :r";

<

2. Assault Forces

5. (a) General

An assault in this sector offers favourable chances for success provided, that we can seize and hold the IxESSAY-CAKENTAN area. This will disrupt the enemy's line of communication on the Peninsula and will delay the rate of reinforcement of his mobile reserves. Such an operation will require the employment of the airborne force to seize the LESSAT-CAPMTAN area, and the simultaneous assault of three seaborne divisions on the beaches in order to reduce the enemy resistance and reinforce the airborne units.

(b) Seaborne

Beach conditions are such that two assault divisions could land simultaneously on the Eastern beaches and one assault division on the Western beaches. However, the number of days during which weather conditions favour a simultaneous landing on both sides of the Peninsula are infrequent. An assault on the Eastern beaches would require that the enemy's batteries in the GRAJJDCAMPeJBa.. be silenced, and an assault on the Western be&ches would necessitate the reduction or neutralization of the island of ALDEKNEY. Such a plan would have the advantages of

(i) Permitting the main assault forces to be landed on beaches sheltered from the prevailing Westerly winds.

(ii) Landing the main assault forces close to the important defensive area, LESSAY-CAEENTAN.

(iii) Providing alternate beaches on the Western side for the build up if the wind prevents the use of the Eastern beaches.

(c) Airborne

Airborne forces can be used with the maximum effectiveness in this sector inasmuch as the important terrain feature, LESSAY-

- CAKEMTAN, must be secured by our forces as quickly as possible in order to delay the enemy rate of reinforcement, and only by employing airborne units can we be assured of reaching this area before the enemy reserves do, as time and space factors, and

: ! tactical dispositions, favour the enemy.

Comparison of rates of reinforcement

6. While it is possible for the enemy to-concentrate quickly considerable reserves against the base of the COTEMHN Peninsula., it is estimated that two of our divisions could successfully accomplish the mission of reinforcing the airborne force holding the neck of the peninsula, inasmuch as there is not sufficient room to permit the deployment of the total enemy reserves against our forces. Only a division in reserve actually located vdthin the Peninsula would be able seriously to interfere with our rate of build up.

Air Forces

7. Air Force considerations in this sector are comparatively favourable with respect to our ability to provide air cover and support from the UK. At the s£me time, it affords the least advantage to the enmy in the conduct of counter air operations as there are comparatively few airfields in this general area from which he can operate and it is remote from the major concentrations

3.

of enemy airfields immediately EAST of CAEN and NORTH of the SEINE. Airfields a*L.. airfield sites suitable for development in this area are few, but all factors considered, the .COTENTIN Peninsula is favourable from, the air point of view.

Naval •; .. :

8. Prom a naval viewpoint, an operation in this sector is generally favourable. The early capture of the port of CHERBOURG and its deep harbour, the complete blocking of which. would' be extremely difficult, and the fact that movements on the.Eastern side of the Peninsula are iri. sheltered waters, 'are distinct advantages. On the other hand, assault operations - on the. Y/estern Side of the Peninsula w<?uld meet generally unfavourable weather conditions on the beaches. Prior to a:qy movement cf vessels in this sector, the reduction or neutralisation of the Island of AEDERNEY is a ^requisite, Additional forces would be required for tbie defence against enemy E*-boats operating from nearby bases. ; ': •-'':

Supply and maintenance

9. (a) Supply ^nd maintenance considerations in.this sector are favourable for the initial phases of the .operation. . The capture of CHERBOURG would'provide a major deep water port which is well protected by a breakwater. . ' j • : , v : . .

(b) It is estimated that a total force of twenty divisions can be maintained over the beaches arid through the ports of CHERBOURG, BARELEUR,' and ST VAAST>- for. that, period during which reserves of • supplies are being established. Once reserves have been established and port capacities jare fully developed, thirty divisions can-be •' maintained for; lifted :periodi ... However, it :is not possible to , * provide, maintenance _over/.the .beaches on,.this ;scale for' an extended period. There after, the ports alone, with a maximum capacity of ten divisions, would have..to supply the force ashore. ; The improvisation of sheltered, waters mry provide additional maintenance capacity, but in no case now conceivable will this be sufficient to maintain the remainder of the thirty divisions.

(c) If by dint of a break-out through the neck of the Peninsula, the greater part of the lodgement force should be anabled to operate outside the Peninsula, the line of communication necessary to maintain it would consist of two highways running SOUTH from CHERBOURG., The Eastern of these highways passes through the dargerous bottleneck at CARENTAN; the Western highway would require extensive engineer construction to make of it a first class artery. Such a line of communication would not be dependable as the life-lino of so great a force.

Tactical and strategical

10. The object of the operation is twofold. First, we must secure lodgemerrt on the Continent, and second, we must gain sufficient deep-water ports to accommodate the laixding of large forces from the US.

(a) The possibilities of accomplishing the first part of the object by landings on the COTENTIN Peninsula appear to be most favourable. However, even if a lodgement in this area is firmly established, the

• forces ashore will be in a position where they can be contained by an inferior enemy.

4#

(b) The limitations on the size of our forces and resources are such that the hazards of the assault should be. undertaken only to gain a decision. In assaulting the Peninsula, we undertake an* operation, which even if successful, does not dispose our farces in a position, to gain a decision that mil allow the accomplishment of the second and most important phase- of the object, since the size of the Peninsula will-not permit the operational employment of more than eight to. ten divisions. If it is possible to-emerge from the Peninsula, we will meet the enemy v/ith only part of the forces available to us. If the force landed is unable to emerge from the. Peninsula; then a second seaborne assault will be required v/hich will be reduced in strength by the amount already contained, and which will have to assault beaches already reinforced by the . enemy reserves.

CQNCLUSEONS

11. That the assault and occupation of the COTENMN Peninsula will not accomplish the object of the operation because

(a) There is insufficient port and beach capacity to maintain a force greater than ten divisions over an extended period.

(b) The Peninsula is so an all that a force larger than eight to ten divisions could not be operationally employed.

(c) The restricted exit to the Peninsula -would probably render future offensive action on the Continent difficult, if not impossible, without additional large-scale amphibious operations.

'12. That the assault and occupation of the COTENTIN Peninsula would require that the Island of ALDERNEY be reduced or neutralized.

: , V v - W • . A E F E N D I X j ' ' OHiiRATION'10"VERLCRD• ' . ' to mS^Od^TZB : .

. • B#LICATIOlfe OF THE OARC.IJEE OF AIPERNBY • '

* _ : , -T' .. .. INTRODUCTION ^ "V

1* The island of ALDERNEY lies twelve miles to the YffiST' of,:..(JAP DE LA HAGUE, the North-Westerly tip of the CONTENTIN B^mnsula; and aome: hineteen miles NorthrEast of GUERNSEY, The long range coast defence guns, of JERSEY, GUERNSEY and AXI5ERNEY. have interlocking.'.arcs of f ire which cover the approaches to the- jfeST e.oa.st of the CCTENIIN ifeiiinsula. furthermore, RDF installations .. on these is'landsvapprgciaMyfrextend the:.:.:enemy',s RDF coverage against' surface v craft and aircraft;, The capture of ALfcEHNEY would form a gap. in the enemy's .fire plan which would enable shipping and craft to be operated- on this coast and would reduce the extent of his RDF coverage, . , ; ,

OBJECT ;J?i

2, The object of. tKis, appreciation is "'to consider whether .it wq^ld lDe' expedient to capture :AH)ERNEY .either before, durihg or after a ianM^ "in. the ' CAEN area, '

:: yTHE CAPTURE OF ' A@ERliSY: : .

Topography • ' , . .

3, ALDERNEY is about four miles long by one~and~a~half miles1 wide. Itr is oblong in shape and is divided into, two-parts - a high.rocky plateau on--the .; , WEST; and a lower hilly area^; f©3rtniiig about :oae~sixth of the; area of the island, on the EAST. There is one emergency landing :ground: but it is unsuitable for modern types of aircraft, . - ; v •

Beaches and ports • : ' •; "• ' . '

4, The Southern and. Western sides of the island consist, of. a. high precipitous coast fronted by outlying rocks. The Northern and Eastern.sides are not so precipitous, the. coast consisting of a series of baysTof sand and gravel separated by steep projecting-points and the ground rising steeply ..from the fore­shore, ... The most favourable ..beaches for landing are those in'the NCI^TH, namely, SALINE .and CRABBY Bays and BRAYE HARBOUR. On the SOUTH coast: LONGY:BAY Offers'the only .suitable landing place;. None of these beaches has particularly good exits and all of them are dominated by high ground. The remaining beaches have -difficult seaward approaches and steep, limited.' exits, i,'

ERAYE HARBOUR is the only port oh the is land j. ,-,vi-ts-^a|)aQi't3r -wot& be sufficient to maintain the force required for this operation*. ...

5* r - T h e t i d e s a r o u n d t h e i s l a n d a . r & . e x t r e m e l y s t r o n g , a n d v a r i a b l e , ; the approaches are 'made difficult by numerous'' off-lying rocks. Before the opera­tion could take; place it would be .necessary to have a smooth sea with no swell,

^visibility not. less than four miles,, and. a, moon between the ;first and last quarters being up during the- initial landings, ' "

Enemy resistance :

6, The island is strongly defended by coast defence, and AA, artillery, ,and

near the G(^isjfev-U'i0W S-ni!-«aaM£Diis machino-gm positions with defensive wire. ' • The majority of the positions are in concrete arid deep concrete shelters exist. Concrete ^ti-timk-walls are bein^ erected jvfc SALINE BAT and LONGY BAY and mines arc being' laid on most of the beaches... A..boom,..n0yv exists at BRAYE HARBOUR.

The total s trength. Qf^ii.he. enemy. .ps r 39nne 1; on thajisland is about 3,750. Apart from the labour corps, coast defence and AA troops, there is a battalion group of the 319 Infantry Division r\nd a few FRENCH light tanks,

Bnployment of airborne troops

7. The island is suitable in parts for thelanding of glider-borne and parachute troops. The strength of the encny defence system, however;* would pre­clude-their use except'after very considerable preliminary air bombardment. If this was carried out, parachute troops !tiii£fet be-Employed to disorganise the -enemy .resistance in the period just previous to' ftrid during- tfie: assault#

Conclusions ": •

8. The assault should be carried out mainly by seaborne forces - pos­sibly with the assistance of parachute trc^giy In any case no landing can be undertaken unless the defences are previously destroyed or neutralised. This will entail air action on a large scale. ... " 1 •

9. In spite of such neutralisation it is possible that the beach ob­structions still remaining will materially slow up the landing of infantry and may preclude the landing of MT, except through thu pclrt, until considerable RE work has been carried out on the exits.

10. From a study of the beaches, it is considered that the main seaborne assaults should take place against LON.'-rY BAY and GAD IN. HAY.

Scale of forces required ' ' . :,r _ - •

11. A detailed plan*' for this operation has been -recently worked out," known as operation 'CONCERTINA'. According to this plan the forces required would consist of the equivalent of One brigade group with the minium of transr-port, • one squadron of tanks and two commandos. This would constitute in ships and craft approximately two-A.nd-a-half flotillas of LCT, six LSI(H) and two flotillas of LCl(S). 'A he;avy scale of bomber-effort over--a period would be required to soften the defences, in addition to the provision of fighter cover and close support. : Although'not included in the plan, the co-Operation of air- . borne troops is worth consideration.

ADVANTAGES OF THE CAPTURE OF-AIDERNEY ' /

Operational aspect L-: ..!: •'

12. . The capture of AIDHRM3Y would enablu the sea approach to the 'ANSE DE VAUVILLE to be used by subsidiary' assault forces with interference only by guns on the CAP DE IA HAGUE..

It would also prevent th£ operation of the 'existing- .GERMAN. RDF ; . system from that island. '• •

Maintenance aspect . . . .i;. rr ^

13. Owing to the limited capacity of the ports in the C^EN - COTENTIN area, it will probably be necessary to-supplement these by beach Maintenance over a considerable period. The EAST'beaches of the CG^-ENTJN are likely to be used.for

this .purpose. Under certain weather conditions these EAST "beaches may become unusablej during which time it-might bo desirable to have the WEST beaches' available as an alternative. , Before these WEST *be aches could be used it would be necessary-' to:capture ALDER3PIY..

•''fT'lj0:'v6l'-jminati.on of. the. coast:defence guns on AEDERNSY would also. : facilitate tfeMb^ement-of-shipping into QI-ERBOTIFe-from the WEST.

A-J. : HigNG.Og CiJPT.IHE 'IN RELATION. TO. 'LiMNS IN THE CAM AREA'" '

14. . The capture must.be timed to take place either before, during or after a'" landing in the CAEN area. • ' '

Before the. CAEN operation '

15. If carried out before the CAEN 'operation, - it would be possible to use the beaches in the ANSE DE VAIXVILLE- for a subsidiary assault • landing, if desired; ' and also as alternative maintenance beaches after the COTENTIN Peninsula had been captured, 1

16. On the other hand, the enemy is likely to consider the capture to be .a preliminary to an operation against- the CAEN or COTENTIN sectors. He would, . therefore, concentrate his reserves accordingly and would.'strengthen his defence, of the beaches. "

During the CAEN operation ' • "

'17.' ' It may be found during the CAEN operation that the force advancing • into the COTENTIN to capture CHERBOIIFG-is unduly delved by enemy resistance. Itj

may then be desirable to outflank this resistance by carrying- out an assault on . the EASE or "WEST COTENTIN beaches. If it is decided to land on the WEST COTENTIN beach it will be essential first to capture ALDEENEY. ' • •,

' 18. The capture of at this stage could probably be carried, out • with little d.iversi on from our main effort. An assault force'would, have' to be

trained in addition, to the-forces taking part in the main assault in the CAEN area.-

- After the CAEN operation ' - , •

•19. After the CAEN operation has taken place, the factor of surprise can be eliminated. Moreover, the morale-of the garrison -should .have been layered and the' operation rendered less expensive. .. ;

CONCLUSIONS • ' >

20. The capture of ALDEHN3Y is necessary if we require to use the "Western beaches of the COTENTIN Peninsula for ma.interj.ance purposes. If .it should be considered desirable to ensure the use of the Western beaches for subsidiary landings, in the event of the capture of CHERBOTTffi-being delayed, the- previous capture of AIDERNEY is essential, since, the sea conditions necessary .for its assault a.re such that, it is unwise to count on them being favourable at.a part­icular time, e.g.', during our o.dva.nce up- the-'COTENTIN Peninsula. •••'.' ,

21. It is .undesirable from the purely oper0.tion.al point of view to . attempt to capture A1DEENEY before the main ope raid, on 'against the CAEN beaches. This would focus attention on the CAEN - COTENTIN areas. On the other hand the MT- requirements for AIDERNEY are so small that the withdrawal of ships and craft p r e s e n t s l i t t l e d i f f i c u l t y . T h e t r a i n i n g o f t h e a s s a u l t b r i g a d e necessary f o r the operation should not be a.-heavy commitment.

22« There is no $oubt that the recovery of the". CHMNE1L JSI^NDS is likely---to he an early exploitation task after a lodgement 1ms- been 'established on the Continent, The- capture of might;.,well be under taken..bef or e . the other is land s; as it is liKeljy • to: .be;, the:. 'least expensive, :to :oapture and its fall' •should assist in lowering the morale of the garrisons of the other "is lands as ;V: ' well as giving us more, freedom..'of..-movement- at• s;ea.in;roperacions against them.

r

jte BRITISH •

'' igggMa to GOSSAG TXIT 28

OPERATION 1QYESLOBD1

THE POSSIBILITY' Of A SUBSIDIARY COMBINED AIRBORNE. Aid SEABORNE OPERATION TO"CAPTURE HAVRE .

INTRODUCTION'- — : '

1 . r , . .I t is , . . . a s s u m e d ? t h a t , t h e . ; . o p ^ r ' a t i o r i s i n t h e C A E N s e c t o r h a v e h e e n supcessfitl an4.; that;:th ;:Gap:ty.rp'-.o£ tiW BRITTANY .ports has been completed. During .-this iatte£,j$j$§$, ...^eguecfce' forces and equipment will have been. huilt

.axrfields.-.gvi^iiniifi) operation for the. main advance across, the SEINE.

v , • • By this tiijie, ; it is- probable that, having failed"in their initial efforts to destroy,.^T4y,,bridgeia<3ad, the bulk of the GERMAN forces .EAS^'of the ORNE would be regrouped and withdrawn SE, both "to cover PARIS' and to" threaten in flank any Allied, attempt to advance to the. .SEISE, ports,* , .

The-.GERM&NSr;ffill probably be: hplding,:the.line of the SEINE with reserve (training), (^visions or ptfiep^,d§fehsive' tiyoqps from''the interior. Some mobile reserves will be grouped'NORTH of tlae' SEINE/ ready to' reinforce the PAS de CALAIS area or to... Gounter-ai'tack any advance-, across the SEINE or direct ten HA.VRE, The enemy must""be assumed to be' holding the. PaS de CALAIS coast firmly, .... r,;..,

OBJECT ' . ; ,,

2« .To examine the possibility of capturing the LE Jl/iWE Peninsula by a subsidiary combined seaborne and tjb"''c0incil3& with a major advance..across -the. SEINE,..,-,

SYSTEM OF DEFENCE, . - '^'y, ' . . . " ,!!-,r'.

3» • present order of .battle is unknown^'' the 'sect'or' has in--the past been held with-three regiment,s.up- one' from HiiREEEUR - OGTEVILLE, one from OCTEVILLE~ YPGRT, ' the third from FECAMP' - ST VilLERI»EN-CAUX,; each

in..rese£vek. . . ;

if.The:major .cpncentra^ion,,pf coas.tal,. field and. AA artillery .'is, however, grouped' in and aroundj-theJpQ ,-'-which; the enemy appreciates as being-1 a: vital eoid ve.-invader, ... ..The defences of the HAVRE area are, therefore, likely to be strengthened,..rather' than weakened,';" in the event of landings in adjacent sectors. 'The town and port itself is" ' defended against a seaborne attack by infantry positions supported by medium coast artillery and AA batteries, the majority o'f:';which are;:-i-n- concrete, Ma|iy:'-6#:%he heavy M'batteries, are-:-als.o' sitpd,.:fp^ an ;anti~shipping role. . The'-port -is -also-defended, by .a series-,:pf booms*, probably be controller-mines "in -the harbour approaches arui,;^ctoljip^ may;bp^ in the entrance, -To guard against a land attack from the rear, a"; defensive position including prepared a.rtillery positions has been constructed on the general; "line HARFLEUR - 'River LEZARDE- -FONTAINE ;.LA MALLET,. - OCTESILIE. The River LEZARDE has been-artificially 'flooded' for two thousand yards inland from HARFLEUR, The normal, -strength of the HA"VEE .garrison is . estimated at approximately 6,000, including coast defence,. M ahd-QtW troops, " ''The garrison would be likely to be increased with additional defensive troops in- view of our success In the .CAM sector..

AIR

that the enemy will have suffered a major defeat in the air by this time* He willj however, ; .still have the use of his main concentration of airfields in the'- PAS' EE; CaLIIS'- "from which he could operate,, ..albeit intermittently, over the.; MORTH SEINE . sector. ...

Our forcpes should be able'to uriderteice the added commitments of covering the main Easterly advance and a subsidiary attack on HAVRE*

THE MAIN AMD' SUBSIDIARY ATTAQ^ "'^ '•

;6*L ; "'^'Owing to the. fact that: there are MKiia^turai -.positions'--:at- a i&Itable 'distarice from. HAVRE. on which the. :;siabsicli.ary..--•-force.----ooi3ld:- fo&i a

it'" will be necessary .to .begin /fche. a anc.e, :,across/ the SEINE-' before the' Biibsrldiary assault begins, with the purpose of containing enemy reserves,. • ..The subsidiary attapfc;:,.wil;I>: J:have;;:no more than the; coast defencas.laixd imediatereserves, tpv:CQntendowith^j:..;.'And further* the" co^st&Xj'.d MVRE Peninsula, s in ngotheir:- lines ooinmUhiQa tid'sS" j j'Ji ea-fcene iriay. .offer but, small. ,resis ame .:-..:; .:•••;

.THE SUBSIDIARY ASSAULT . . . ; v.-v.;,: Lav

]T«~[ ' There are-three possible -methods..ofr;ccarrying-out a subsidiaryci 'dperation to1' captux e the IJAVRE.Peninsula ('o Thego&£§$r • u'L

(a) By an airborne.'assault• r;'!'i *zxo>~- v.;....

(ib) By a seaborne assault. .• :

(p) ,vBy. any oombinatiQn rqfr.itke above JM adsi-T'

Use of airborne forces , •'o.c- jOiii i-': C.-'-

8, The airborne division used _ operation would have been withdrawn and would' Have -had time to refit and reorganize, . Onie.,airborne division might §-till -be available and held in" ENGI^TSp, . The troop' carrying aircraft jaaid .tugs.; which- took part: in the- origin^- air assaults _might: hay:@';,..suff,arfed considerable casualties and /./£C irdght'have : to bs augmented" .withdrawn from the bomber .effort,

9, , . It is problematical..^hgthei' ao. .airborne division could complete the operation by itself. .Suitable dropping..and landing.zones exist-only to Jthfe.;iNORTH and EAST ' of .the' town,";' Quo.'.:' lancXe'd/; it would have , to obhduot an assault against;;:;i|ie^landward.rdef'ev6ek of.'BiffiE.jiid suffer. interference!,from enemy reserves ih its. rear'*; it is concluded, . therefore, that assist -np-p from seaborne..forces',is necessary,, ^

"' 'Seaborne assaults . ' .

10, ''': The 'oniy"j5laoe 'from which the assault could be launched is: the iJICi':ri'"','This woulfr'xhrolve the retention'of a trained assault force in ^

or tM^Wtfedi-awal of the necessary' troops from FR/UtfOE to ENG-bi^P to

' re foiii. :'' •;. • . .". .... . • MjL;.;i'V. • .' " u

'11, 'L' The difficulties of "withdrawing craft .and': foming, a-Naval,, Assault Force . are not' great, provided .the forces ,a,re .trained, at outset of, tiae opei-ation. .. '' A|proximately seven days':: notice^would be;..npededy and from that time onwards there, would be an interfer^npP:. with'ithe.b ila"~up of the main force over the GAEN beaches to the extent to which, bhe landing craft required for the renewed assault were still being used for the build­

up of the main forces*"

THE COMBINED AIEBOHNE AND SEABORNE ASSAULT

12. The methods of assault might 'be to:-' ' ' ' ' •' • ' ' ' -W • • •

(a) Assault on the beaches of the NORTH SEINE sector, advance West­wards and attack HAT/RE from, the EAST# . The airborne troops could be used either to assist the seaborne assaults by taking beach defences in the rear, or to attack the landward defences of HAVRE and to be reinforced later by the seaborne assault forces*

(b) Assault HAVRE frohtally by seaborne forces while airborne forces hold off local reserves in rear*. A frontal assault only becomes possible when our own forces are firmly established in • the CAEN and SOUTH SEINE sectors, from where air support and medium gunfire can be provided. A heavy preliminary air assault would also be necessary. '•

13# Of the two above alternatives, while both are possible if combined with air bombardment, the former appears more suitable as being a course • " ' which is more complementary to the main advance across the SEINE. The. HAVRE Peninsula would then be pinched qut from both NORTH and SOUTH simult­aneously. A simultaneous airborne attack against HAVRE from the rear would have the advantage of containing the garrison and thus, in part, preventing a wholesale demolition programme which could be put into full effect if the garrison -found itself cut off by the sea assault but not yet attacked.

MINTBNANCE

14. A subsidiary seaborne as'sault would-mean an additional and separate maintenance commitment at a time when the maintenance of the main force would still be in process, partly over beaches, in the OAEN and COTENTIN sectors. The v/ithdrawal of.shippingand craft for its maintenance might well not be a practical proposition if casualties to these had "been heavy* . Maintenance considerations may, therefore, point to the desirability of capturing HA WE with the main forces which would have already advanced across the SEINE,

GENERAL CONCLUSIONS

15 , Prom the purely operational, point of view, a subsidiary combined seaborne and airborne assault is a isound manoeuvre,, if timed to coincide, with the main advance across the SEINE. Its feasibility at the time will be dependent on previous losses .incurred by the. airborne lift and by the naval; assault forces, and the effect that the withdrawal of craft will have on the maintenance problems of the foroe as a whole* ,

OPERATION ' OVERLORD1 APPENDIX 'G«

to 00S§ACr45T28

NAVAL FORCES REQUIRED

A.first assessment of the probablfe'naval forces required in the Channel area for the assault and follow-up-phases of Operation 'OVERLORD' is given below. These forces will be required for minesweeping, close cover and escort of the assault convoys and the subsequent build up convoys., and close support of the assault.

2. It is difficult to form a precise estimate of the requirements so far ahead,, but it appears that nava.l forces of the order given will be required.

3' The Channel area has been taken as the area enclosed by lines joinirg THE LIZARD and USHANT on the MIST, and DOVER .and CALAIS on the EAST.:

Already asked for-in addition

Total

Fleet forces

Monitors..

Old cruisers,

Old cruisers^(expendable) AA cruisers ... Fleet destroyers) Hunt destroyers ) Old destroyers (expendable) Eagle ships

« * » * *

... Up t o 6 2

*

• # • • . 9 »

. if 8

.Up to 20 6

Anti-submarine craft

Corvettes) Frigates' ) ,,f

Anti-submarine trawlers

Minesweeping craft

Fleet minesweepers

**• 9 , « • .*

' # • 9 0 *

. . . 4 - 8

64

11 (HQ ships)

12 (local, naval commanders)

6 2

5 9

20 1 6

72

60 64-

72

Note: Requirements for other minesweeping craft would depend on situation at the time.

Other trawlers

Coastal forces

. . . 4 - 8

Motor gunboats and motor launches 156

Motor torpedo., boats... ...... 72 RN and RAF air/sea rescue craft 100

(subject to confirmation by Air Ministry)

4-8 (navigational loaders etc)

4-8

204-

72 100

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APPENDIX. . ' ' lv- to COSSxiC ,(43) 28

. .OPERATION 'OVERLORD 1 i O-v: (-•

PROVISIONAL ORGANISATION OF .NAVAL 'ASSAULT FORGES

1* ' - Personnel ships, landing ships'and craft will be divided into five natal forces, each of vrtiich cap lift approximately one division, and one commando force which can be divided between the assault forces,

2, . The five naval forces are1 provisionally organised as shown below. The numbers.of ships and craft are taken from the total assets shown in. Appendix ' 'H' » : 'It willV therefore, be necessary when, estimating, the lift of each force to assume that only >90 per. cent of ships and 85 per cent of craft are - serviceable . • • _ • . A

3. (&) US naval assault force

. APA , . . . 7, ships ' I£VP . .. v 70 (carried by APA in the assault)

x ISI.(L) ' 4 ships ;. -. x' D3A : 60 (48 in LSl(L); 12 spare) x LOA ' 15 (special) , ' .• - -•x LOS(K) '•• : ' :V 16 .

• IGS(S) - "E-.•:: . . • LGI(L) 3 flotillas LST; '• 30 ships ;

LCT(j) and (6) 12 flotillas x LCT(R) . 12 craft .'-.s.' - :

x LCG(L) 5 craft : ' •x LCF(L) 11 craft x LCP(L) ;"V 4 flotillas (fitted for making smo

1 .. • ). • • '. • ••• . ;v: ' ''. . • . ' x To be provided from BRITISH sources.

(b) • BRITISH naval assault force

" •' • " ' LSI(M) 3 : " r " : ISI(H) . : ' 9

. ' ISI(L) . , 2 : : ; •LC& '•••• G . , 120 (96 in ships; • 2.4 spare ) LGS(M) - • _ •; 32 V ^;v:v . LCA 30 (special) LCI(L) 3 flotillas

'. . • -LST : 24 ships LOT(3) 3 flotillas' ; :

:• LCT(4) 10 flotillas LC,T(5); and (6) • 2 flotillas •' , LCT(R) 12 craft v' , LCF(L) • • 11 craft. LCS(L) 1 5 craft LCG(M) 4 craft /' Va ',

. LCP(L) ; 8 flotillas (4 of which will be . : "••fitted to.-'make smoke)

I I

•sflBl 2.

(c) BRITISH naval assault force

LSI(L) 8 LCA • 119 (96 in ships; 23 spare) LCS(M) 32 LQri. 30 (special) LCl(L) 3 flotillas LST 2k ships LCT(3) 3 flotillas

, ICT(4) " 10 flotillas LCT(5) 2 flotillas. LCG(M) 9 craft

• LCF(L) 11 craft • LCT(R) 12 craft LCP(L) 8 flotillas (4 of which will be fitted

for making smoke) /

(d) US naval assault force (to carry follow-up formations)

#

Personnel ships to lift 7»500 men AKi 6 ships LCVP 36 craft ) carried in AEa. LCM 48 craft ) 1ST 53 ships

(e) BRITISH naval assault force (to carry follow-up formations)

Personnel ships to lift 7»500 men x 1ST 28 ships LCT(4) 6 flotillas ... " LOT(5) 6 flotillas IXJP(L) 4 flotillas •

x 27 ships from US sources

Commando force

4# The commando force may be divided amongst the three naval assaulting forces before the operation

ISI(H) 8 LSI(S) k ICk 96 (76 in ships; 20 spare)

25 (special) LCS(L) 2 10 LCL(S) 3 flotillas

Miscellaneous craft *

5# In addition to the above ships and craft there arc barges and minor landing craft --

LBV 2 2kG' L0M(1) 195

. ICM(3 ) 376 ICVP 66o

Merchant shipping

6* it is estimated that the following ships and coasters will also be required:-

MP ships ) sufficient to lift 13,000 MT coasters ) vehicles simultaneously

Small store coasters - 200

AEEENDIX - ,.-/"-"/"• - to .cosa&^TrgS1*-

: ' ATTAiNMBM1' OF THE TCCESSARI AIR' SITUAC-ION

• ANMiTUESS

i^MEXlIRE X /'•"- Estimated air forces available in the UK in 1944 for' Operation ,0Y®LQRpt ,

•". 'Cv' j .1 ' *r ; .EE *• -'/, Strengthjdispositioii'.asifi scale- of effort of the GAP as o.t 1st June, 1943

" 'III . •- Enemy aircraft aSi&'t&feew jpsebxvBS.. " Situation; -S-V • -'."A A, /'•-,-//A/:./-/:A//'''/-.-';.v.:..

r/.. GAF airfields in..the CAEN area.

Enemy RDF organisation, : • . ,

• Enemy day-' fighter defence organisation,

/ -SEBTCfiES : /, /A: .

Airfields :in: UK within range of - the GAM area.

OAF disposition on. Western .Front: as at 1st'June, 1943.' . '. . . • . ;

-• "GAF fighter and maintenance facilities on the ' ; a '••'•'1 Western Front,: •••;•••. : " " „ ---:...//

SKI? -• GAP- airfields within 25&:'ffliles 'of.• CAEN.

SKV ~ Enemy PDF cover on the Western Front,

/ '•' . ' SKTVI. - GAP fighter -control' system, - -• '//

Probable general air situation in 1944" ' . . . . . - ; : g . : ' ' ' •

1, . - "• • It is impossible to forecast, the strength and" the' fighting' yaiue.: : ? -

of the GAP in North West EUROPE in ••'1944,'"''paxticuiarly in' view of the fighting, which - it : is .anticipated will take •.plaee/ift?' the'J^iterraijean'" in'th^; V course of the main 'strategic bomber ioffensive and possibly/in Operation1 • 'STAEKEYf« It will there fore be some.'iaohths before-a "proper assessment: oa|i': be,jnade,,; .' ' /: ..': ' - '•//'; - AA'.-/A'./-- :: / .'" , J• /"./•-'/A/'."'"

2« ' - - A definite and highly effective local superiority' ..over ths-'(je.r#®"'\ fighter force fell be :an/'essential'- pre-requisite' -.of any-:at tempt ,to return' to /V the Continent since it is only through-freedom, 6f action of our /own air "A A forces/ that we can offset the. many and great-disabilities inherent in-the situation confro3iti.ng the attacking /-surface' forces,

3. There is at present a definite- and steady increase in the first-iins strength of the German fighter force,. A Moreover the enemy has adopted:the/ /, policy of increasing the .number of-his first-line day- and night fighters oxi' '• //--the Western Front at the expense of other fronts and5 the size of his .reserve,, •

" 17

" , V

I I : V I

SKEI'Cff ; SKI

SKII

SKIII

/Relative,«

. f / •% *• ... • • - » > / , . / f£ * -

• - • ' - - # ^. *r > \ •f ' " aft '"* : *•» -i >> ' -, •

• •• r\ •*- .. " /* Jp * |f

Relative strengths. :-w , *-

4. Although we are unable to ••forecast, the strength of the German Air Farce in 1944,.. an examination of tlx- xnemy- ai-r situation as it existed on the 1st June, 1943, is givp».in imnexure II as a basis for comparison and as a guide to the proportionate dispositxoir<5^""enemy- a-ir- forces :pid: their potentia­lities. On this basis our own air strength*-Retails of which are given in Annexure I, shows a vast numerical superiorly but the relative strength of our fighter forces will be 'much-reducedat .the;; point of combat in view of the distance from their own bases at wfiich they!will have .to . .operate and" the many 'commitments with viiich they wi,ll be faced. , ''

5. During the assault, our. sea and land forces become most vulnerable to air attack, not only the forces on the beaches,but also the many hundreds of surface craft plying across the Channel* These will require air protection which can only be done by standing patrols, it will also be necessary-to give fighter protection to our own bomber, fighter/bomber," reconnaissance and troop carrying aircraft. In addition the security of our own concentration areas and ports cf embarkation must be ensured, • -

6. We shall .not know when and where to expect the- enemy ,to attack, but it can be assumed that his main- object will be to prevent at all cost, a successful landing on the Continent. The Germans can elect to mass' their avail­able air units and attack our surface elements in maximum strength at any hour of the day. and in effect, two or three "times during the day.

7. A-yfide, dispersal of our fighter strength" to guard against all contingencies would so dissipate our forces, as to be beyond our cp-pabilities and we must therefore -first attempt to reduce the'effectiveness of the German Air Force, particularly thr.t which can.be brought to bear^ in the CAEN area, to an extent which will enable us to provide security with small standing patrols and escort forces within the capacity of the, forcer: available.

Enemy fighter situation in the CAUT area •

8. Provided that our preparations for the assault against the Continent are such that the enemy will not be aware exactly when and where the main assault will be directed, and that'the Allied bomber, , offensive is being maintained against GEEMANX, it can be assumed that the German fighter foKie will be disposed much as it is at present. With such disposition the enemy ^fighter opposition which - oould.be brought to bear, initially iri 'tfe iraptf&sewfefi. ¥1% .of. the total' day ;fighter strength on the- Western. -Front. including NORWAY. This force* --could, by means of rapid' reinforcement from the rcgnairtder of 0LWCB, the, LOW COUNTRIES -and North West GERMANY, be almost . doubled in strength during D day, but only if. the- enemy is prepared to denude .these areas of all day fighter protection. If, however, the. enemy -retains:£i- minimum defective screen in-other areas, he. would only be able to increase his strength in the CAP! area on D day by. , ttp^oaeiimtpDy^a.:; fctlf*" It is clear therefore that we mu^o contain the maximum r

number orf enemy fighters in the •'main-,area.-from which rapid reinforcements could be drawn, naively, the LOW (X)I)Ml!RIES;:;'an^-:JIc>rth -at-the-, same, time as. we reduce the effectiveness of the ener^ fighter force's in-,:thescASIf..area...

9. ' Over'and above the -immediate reinforcements which could arrive on'D day and to which: reference, is made in para> 8,"further reinforcements could only be obtained at the expense of the IvIEDITSRR/iltViN and RUSSIAN Fronts. Reinforce­ments from the MSDITERR/:!NEAN area are hot like 1# to be:, available prior to D plus 4 and from the RUSSIAN.-Front' prior 'to D plus 14. It is' On. these reinforcements that the enemy would depend for sustaining his scale of effort, : .,

/Relative...

- 3 -

Re la tive s eg les of e f f ort ... -

10. . . A very large; scale of effort will be retired initially from our own fighter;force in view of the distance at which it will "be re quired to operate fran our; own. "bases, But' cwing to fatigue-- and to-' losses incurredv during the early stages of the invasion, this high rate of effort will fall off very rapidly. In order, therefore to maintain our initial advantage it is important that the enemy shall not be able to sustain his scale of effort by bringing in reinforcements from other fronts.

ConclusiQn •- • .

11. ; Our plan must provide '-hot only for the reduction of the German , fighter .force J^'hiph could be brought, to bear initially in' the CAEN area but,also., for containing.the maximum f ightGr'' forces' in the 'LOW COUNTRIES and North West; GJKMoNY -aiiM in the SJEDnJ-KELyflSAN area. : : -

Reduc,tion of .the German fighter force in the CAEN area-'" T

12. : jhe effectiveness of the German fighter iforce ih the CASN- area depends r on the ..s t r e n g t h o f ' e n e m y f o r c e s i m m e d i a t e l y " A v a i l a b l e , : t h e - s t r e n g t h . o f j : -his reserves, tfjy number of suitable* bases from whichnhe can operate, ihis .-air. :, warning system and, .his fighter defence organisation. '3ach of these, element is':. is discussed in detail inAnnexures II, III,- IV and VI respectively.

From iinnexures .il coid IH it will be seen that the "enemy has concen- r trated. his availpble aircraft for operations in first lino units and is lacking in rose ves. " if therefore a high degree of waata e can bo inflicted on these first line fighter, units, the scale of- effort^ which 'he can. Operate will fall-UJ

off very rapidly, VV..-7 . ' v rr.r, . v>. ; r—cr.

13. The possible methods of reducing'the offeotivontss of the German fighter forcu arc: -

. ( a ) - D i r e c t a t t a c k b y b o m b e r s a n d f i g h t e r s o n G e r m a n f i g h t e r — :• •• , units. (Note; Attacks against aircraft production and::

;. . pilot, trainingis' not included as it is' a long term poliqy<ij;,/ q; • v ' . y h i c h i s c o v e r e d b y t h e s t r a t e g i c a l b o n i b e r p l a n ) : * .r . : wn This includes . y • •: ni; yi rnr.:;

..... (i) Air combat by "forcing the German fighters to action . . . r b y a t t a c k s o n v i t a l c e n t r e s . . , i : i . - • . - j . r ; H r ; n

, (ii) Mr attack on airfields, v " b 0

... • (b) . Destruction bf Gernmi fighter aircraft and their.crews, by -; airborne attack on airfields. ^ , v ;

( c ) D e s t r u c t i o n o r d i s l o c a t i o n o f c o n t r o l a n d c o m m a n d . T h i s includes

( i ) D e s t r u c t i o n o r j a m m i n g o f e n e m y a i r w a r n i n g s y s t e m ,

• ': (ii) Destruction of Fighter' C ommand'' Head quarters, main aircraft Control centres, (Jafuc) and main airfield ,

- contro l; centres, 7 ,\

/Destruction

- 4 -

Destruction of! GAF by direct, action

14, The fighting value of the German fighter force must first "be reduced. Once that is done, it will be relatively easy to provide adequate air support for our land';a«id §ea. forces. Alternative methods are air combat, by-wearing, otft; the fighter force-,; by .destroying it in the air, and by air attacks against air­fields'.'

Air Qombat . ' "

15« The main task could only be accomplished in daylight though at the same time a sustained rate of night bombing would be necessary to tire out the enemy ' defences. The eneny will only be induced to fight in defence of vital centres, or under conditions which are favourable to him. This means that our bombers, in making these attacks, will generally be outside the range of fighter escort and \ the probability of reducing the available German- fighters in; large numbers in a short space of time by these methods is uAlikoly to be practicable. "In any event,' this is 3. complementary part of the main strategic b.omber plan and some time must elapse before the results achieved by this means can be assessed. 'Jin' alternative method of bringing the German fighter force to battle and inflicting heavy casualties is by means of a majdr feint.., such as Operation "STABKSY1'. Such an operation provides for the main fighting to take "place" in'an~ a^a:;a4vantageoMS • to our fighters and if successful, should result in a high.rate of casualties to the enemy in a very short period of time. Unless a large feint operation is undertaken, prior to our invasion of the Continent, we shall have to depend on forcing the GAF> to battle repeatedly on a. large-.scale in areas which generally suit than better than they suit usi' This process, will have to continue'for a-long time and it is not possible to assess the results likely to be achieved by ary -given date. We cannot, therefore, rely on this method r.lone as a means of reducing the effectiveness of the German fighter force in time'fdr .ani invasion of the Continent in 1944, and our plan must include a major feint operation to bririg ; on large scale air battles in areas advantageous to us. .

Air attacks on energy fighter airfields

16. Details of the German airfields available within enemy fighter range . .. (150 miles) of the assault area are given in Annexure IV. From this it will be : seen that there are some 39'primary airfields, 28 secondary airfields and 28 emergency landing grounds. . Of all these, only some 12 hp.ve been regularly used for operations by enemy fighters iri the: past .12 months... Much will depend on the actual location of German fighter forces in this area and of'accurate and up-to-date information in early 1944. In view, however,- of the large number of air­fields available to the enemy, it is clear that any attempt to reduce the effec­tiveness of the German' fighter force by denying bases, to him will be impracticable. Nevertheless a vigorous offensive against the enemy installations on the main airfields in use and by the destruction of aircraft located thereon must form a part of bur plan, not only with a view to reducing the strength of his units but by compelling the enemy to operate from bases more remote from the scene of our assault.

General conclusions on first method

17. There is little likelihood of neutralising or destroying the German fighter force within range of the CAEN area in a short space of time prior to the assault. The German fighter force as a whole on the Western Pron^ must first be reduced by bringing it to battle in an area advantageous to us' and by the long term bomber offensive (Operation 'SICKLE'). Direct attack against German fighter units and airfield installations in the CAEN area will.then be possible and at least will result in compelling the enemy to operate from bases remote from the scene of the surface assault, thus considerably reducing his effbetiveness.

/Destruction,

• - 5 -

Destruction of- GAF. by airborne attack <•,

18, .'••••' The• destruction of a. large••,pa^;.of^•the"6e^®all["Mr^•'•Fd^cb' iri:'t'he-:C area'by the use-of-'airborne forces against airfields... is-.,.not..practicable in .view of the large;; number 'of' air fields involved, and our inability to provide effective - . fighter coveir to airborne operations in this area. Night operations by airborne

..forces, in th£ strength which would be necessary t'Q-.aefi-jjeYe^re^uW ':-$3£!§'6v ........ airfields ediii&'ohl^be und0r^teft;:'.QnV'veiy .bright moonlight ,night.s andf in .§uch;. •' • conditions success is extremely doubtful,.'In any, event, these ::operati0^s'--,would:.r'j./; -entail the complete, loss of. airborne forces which will also be required for the distinct land gpejratipns when the inyasion t^ces placeThe.; use ..of jiii'-bprne forces' as &. mearis "of^redadiplVthg^Gennan Air^Eorce' prior::to tte invasion is'not therefore considered desirable'.': ''' '. 'l

Dislocation of control and1 ^dimari^'

19', ;' •. gneny/' air warning .sys tern .

The 'enemy RDF organisation is examined in detail in Annexure V whefe-in it is deduced that the effective destruction, of.. this,, organisation by-air attack is not practicable;' inNM^'of't.he':nii^ stefLons/ involved ,§.nd :Jche speed .with. which thwy can b ef-teplabed by' mobile^ e qui^efit,", ijitt.empts, tp- .^reduce, the:;.effecr- .-'v. tiveness' of the air warning system by technical means rather than by air attack Fh;

is therefore tho only method open to us. In a,ny event, the reduction of the air warning system;- should\'not''fork part''of''' our air ''action':.pripr.to .the- assault,,., so v'" that full benefit cari b e derived, from" "fcfiigs:, aM?pcl'so ;ii^iasure- at" the .tiiim pf the ;- . assault whrn/'he'^Yill havd' no' time- to' institute ..counter measures or to iisprovise an alternative system, : ^ _

Destruction of the OAF fighter command. headquarteys:: , r. _:y; ' and control ceritoes';'ih;tfe' "CAEM'area • -CyO

'20,.. : ; .The command and -operational, control of -enemy.,day., fighters-is f described in detail .in Annexure Viy-from;wiiicjl it,w:i"il be.,'se:e.n.;.that the key points in. the e n e n y ' f i g h t e r c o n t r o l o r g a n i s a t i o n ' a r e 7 . - . : , : •

(a) The Fighter Contaand;-Headgi.u?J?ters,. located .at CHAWTILLX,: ( : : . (bV .The dirc£aft:,do^^ .(Jafue).^at. BEilJMDOT IE ROGER,

(e) The main 'airfield': cohtrpl "centres "at, . or .near, the', following airfields; ABBFVILLE, TRIQ'OEVILLE,'. affiRBOUBG:.MWJEEKP.US,

. •: CAEN, (^affiOIIRT, . ; : v/-,' • i'. V\: . . /

-21»; As far as is.:lcno«n'"nofie of tlje- atovfi control'centres are ppmplBtely :. underground, and they should, offer.Suitable''targets for concentrated air attack^,, but more detailed information of the Q4act location .of these, centres, is required, Nevertheless, successful attacks 4$&£n&t;; those centres would produce-: a state of disorganisation whidi would :ha'vfi a great/'Effect/in reduding, the fighting efficiency of the Genaan. fighter-force in-this'area. - Further examination of this organisation is necessary, before the likelihood of success of this method can be fully assessed. This method however should not be-adopted as a part of the general plan for the reduction of the GAFj- .bnt\should be delayed until shortly before the -date of the'" actual .assault^ ' - ' .

Genera;! conclusion on the reduction of the '-German fighter , force In ..the' CAEN area , — .

22, - The reduction of the GAP in.the,0AEN area is unlikely to be affected , by any one method alone of those discussed above, A long.term policy of air attrition by means of air.combat as a result of bombing attacks in this area though complementary: to any plan,, cannot be expected to achieve .the necessary results a.nd.v\re must therefore at the appropriate time, and after due collection of accurate and up-to-date - information,: direct our air attacks against . the enemy fighter airfields, and. main control centres of the German fighter organisation.

/General, *',,, »«

General conclusion on the attainment of the necessary air. situation prior to the seaborne assault. ... • ':i '• "

23. In view of the operations taking place during the jiext few months, both in the MEDITERRANEAN and by the combined bonibtir offensive, .against the GAP,. it is not possible to estimate accurately the extent to .which ,it will be possi^leu, to reduce the effectiveness of the GAF by 3. distinct series of air operations, /« nor the time required to.complete such operations. It is clear however that successful assault against, the CA3N will require that

: '.Th&-.;Bmij8um number of enemy fighter forces are contained • in the LOW COUNTRIES and North Wqst.-&53MANY.

(b ) The e f f ec t i venes s o f t he . Gorman f i gh t e r de fence o rgan i sa t i on in the CAEN area is reduced. :,-c : .

( c ) The a r r i va l o f e a r ly enemy r e in fo rcemen t s f rom the - MEDITERRANEAN area is prevented.

24. Above all, however, an overall reduction in the strength of the German fighter force between now-and the. time for the surface -assault is.;-essential The strategic bomber offensive against the German Air Fo^'ee may retard the present expansion of the .German: fighter force. But -the main deterrent-to the success of this- long teirn policy, is the- existing first line strength of the German day ; fighter defence. The infliction of heavy casualties \in a short space of time on . the German, f i^iter units, will rernovf the greatest obs-tacle to the reduction of 1 • • the eneji^ sources, of production and; tfre- eventual depletion, of: the-German fighter , force by the bombing offensive.

25. The attainment of . the necessary air situation for Operation 'OVERLORD' therefore depends on •

- ( a ) The i n f l i c t i on o f heavy ca sua l t i e s on t he German .. . . fighter force by air battles brought about at an

early date in areas advantageous to us. - . '%•

(b) Long-term bomber offensive against the. sources of supply and production and first line units of the Geiman Air Force,

( c ) The d i so rgan i sa t i on o f t he Gcr : ; i a i A i r Fo rce Un i t s -and the disruption of airfield installations within enemy fighter range of the, CAEN area.

(d ) The d i so rgan i sa t i on o f t he ma in e l emen t s : o f t he German Fighter Command and control organisation .in the CAEN area* . - .

ANNEXORE 1 to APPENDIX 'K<

to COS,SAC(43) 28

OPERATION 'OVERLORD' AIR FORCES AVAILABLE"(AMENDED)

• 'USAAl? . RAF

Squadrons Aircraft (UE) Squadrons 0 Aircraft (UE)

HEAVY BOMBERS ' 204 2,448 80 i.;6oo

MEDIUM BOMBEES 36 576 12 240

LIGHT & DIVE BOMBERS ' '52 . j 832 13 260

BOMBER RECCE . I

1 . 1 • 14

DAY FIGHTERS 100 2,500 | | 44 792

NIGHT FIGHTERS 6 150

FIGHTER RECCE •15 231

MM SUPPORT (FIGHTERS) 8 112

ARMY' SUPP0RT(BOMBERS) . k 56.

PHOTO RECCE 8 168^ 5 100

OBSERVATION 16 336 i

10 160

'Ait/sM Mlttfe

TROOP CARRIER

|

Ovl ~^

r -=

T

8i j

7

170

190

TOTALS 1 «o S

r j 7,302 2l3i

! - - -

4 >075

G. L I D E R S

US '

CG-4A 1141

BRITISH

. HORSAS 146 5

H&.MILCARS 146

- TOTALS 1141 1611

0 ' These squadrons represent those that will be formed or forming on

1st January 1944) which will allow for their being fully operational

for cross channel operations on 1st May, 1944*

BRITISH AIRFIELDS IN THE UK WITHIN RANGE OF THE CAEN AREA (FIGURES INDICATE MAXIMUM FIGHTER SQUADRON

SKETCH SKI to APPENDIX 'K

MILES 100 5 0 100 MFLES

3 VLI ELAND

TEXEL

3 6

'AMSTERDAM

<— O ROTTERDAM

O* WALCHEREN

CALAIS X.« BRUGES.

BOULOGNE

<? CHERBOURG

DIEPPE

ETRETA;

BREST LE HAVRE

BAYEUX

(ROUEN

I co$s»s;A-if t 4

• *

I

• - ' • • • • " ' T^-rrf-royr '"' :gggggg^

-AKKEXIEE II to AEBEMDIX 'K' to"G0SSAGD5T""g6

: STEEM3TH,- DISPOSITION AND' SCATS W EFFORT " ^ ... , OF THE GAF AT JUM! 1st, TS45 ™~

; - ; • . .../ Sketch SK II.,-i/3?isposition- of GAF on . the - >r: WesterijJj'rQKi. - on 1»6.43»

1. Any/accurate forecast of the possible dispositions'and-vseale of ' •• -enemy air effort against a particular operation 'by.us as far-ahea4bas -Spring of is not possible. • The following appreciation, however,, based'' on certain assumptions and an analysis of the enemy air situation as. itrvrf' T-existed on 1st June, 1943 will form • a "basis for comparison and a guide to the proportionate disposition of enemy air forces.-and, their, potentialities," :

ISWE / ....

2.< " The ..assumptions on which this ."appreciation is based are as follows:

(i) All GISRllAN air forces on the Jfesterri'Front are substantially -the--'same as the forces which were there on the 1st June1943»

The fighting value, immediate reserves stored reserves and '/•• production of aircraft and crews is the same as on the 1 st. .. June, 1943» •• i-.

The general situation on the RUSSIAN and MpEITERRAMAN fronts is approximately... the/same as at -the 1st June, '1'943V -

; '..... .........' "i" ' The enemy will position .th&3*'=Mr 'forces and their reserves to the best advantage in relation .to the Allied air offensive being carried-cout now and-in the future, =_ ci

The enemy will have''to maintain defensive air forces on the ,:-MEDITE3MNEAN and RUSSIAN fronts," regardless of whether or- not' the scale of land fighting should' alter, . 'Cv-

BASIS OF AFFECTATION

3» She fol.loYri.ng estimates . and • appreciations -are 'based on factaal7"|n^u.AQ)I intelligence and consider the scale of enemy air effort possible under ideal" conditions, not taking/into account any effect that the present:,.Allied.r34^-::; m'!/v offensive may have on the • &AF's; fighting/value in th(2J'future.,

4-» , The scale of effort envisages operations at th§. highest rate of.- in­tensity and only/, takes ..into account normai "b'attie wastage. It does not consider •the fact that if Allied air superiority coulBfc produce eSceseptionallyJ3§&yy'-wastage in the air and/or on'the ground, the scale-of air effort estimated might in

' practice become substantially reduced, nor conversely, that if we fail to-inflict a sufficient degree of/loss on the enemy fighter force between now and the date of the/, operation, the/fffeet might substantially be increased,

5* Furthermore,;:!.the rates of reinforcement are those of which the enemy is physically capable, considering -the scale of efficiency of his organisation as a whole and do not take into account the effects of any counter action by

, , - ^ ^ - , ': ; /;/, ^ |. |

. ; ; , fv"-'; /l P | L... I V1-5/^ U jdtniii . -.

(ii)

(iii)

(iv)

<v)

2 , the Allied forces. The soale of effort envisaged assumes also that the-enemy would concentrate the maximum strength possible even at the expense of adequateelsewhere, "but does not assess in detail what effects such inadequate.Aafia^pe might have,

STRENGTH

6. The first line, strength of the GAP on the Western Front is estimated to be:-

:' r Initial --. Immediate " establishments and reserves

Long range bombers (LKBs) 2"65 " 265 Bomber reconnaissanoe (B recce) 100 ~ 100 Single engine fighters (SEFs) 655 550 Fighter Bombers (FBs) 105 -90 Twin engine fighters (TEFs) 5.25 525 Army co-operation (AG) 20 20 Coastal (Coastal) . 70 • 70

0 105 15 0 0 0

TOTAL - . : ; 1,7W . 1,620 ^ 120

Although the above strengths are shown as IE and IR the immediate reserve aircraft are fully operational and can for practical assessment be treated as first line aircraft. Therefore,', in the. ensuing paragraphs no distinction has been made between IE and IR.

DISPOSITIONS ' ' 1

7. It is estimated, that the above forces will be disposed .On the Western Front as follows:- !

WEST of FRANCE# EAST HOLLAND DENMARK SEINE"- of SEINE and and and

BELGIUM OT.'; GERMANY NORWAY TOTAL

LRBs 150 160 15 • 265 B recce 45 15 15 ' . 25 100 SEFs 140 160 280 ' 75 •655 FBs 60 20 25 0 105 TEFs 60 • 110: 315 . i+O 525 AC 20 - — — 20 Coastal 10 — 60 • 70

1,74-0

SERVICEABILITY

8. The serviceability of the above force by types is: estimated to be as follows;- - .

Type D Day D plus 2 D plus 3 onwards

LRBs . 6($ . 5Of0 40% B recce 60$ %y?0 - • UOfo SEFs 75f0 6Ofo ' , ' 55% FBs 70^ , ; 6C$ $6fo' TEFs • 70fo . 10p 60% AC 7Cffo 6 Of 50^ ' ; Coastal 60c/o 60f> ' 55^

/SCALE OF EFFORT.,,...

SCALE OF EFFORT

3.

9. For the purpose-of^estimating the number of sorties per service­able aircraft over a period ;Qf :: twenty-four hours, the-folltwing table of sorties per twenty-four hours applies ;:~

l^ype D Day 'D ip'lus 2 "j jrlus 3 . -S pius 6 :

IEB» ' lj 1 . 1 B.Recce 1-g- l| 1 1 SEFs 4 4 3 2 FBs 4, .4 3 3 TEFs 2 :. 2 - ~b- :; .a AC V 2 2 ' " l| : • v 1

EFFORT AGAINST CAEN AREA ' - "

10, The scale of effort based on the assumptions--and conditions above and with initial dispositions as in paragraph 7 might be as follows

FORGES INITIALLY AVAILABLE ... -... u.

11. •. Of the total strength of 1,74-0 aircraft on- the Western Front including NORWAY the strength of the force which is disposed so that it could be brought to bear initially against the CAEN area is shown below together vdth the number of aircraft thought to be serviceable and their percentages _ • of the totals given in paragraph 7, ,

Type of Total strength No. of IE '% of "Total" on Aircraft ' IE plus IR ... serviceable Western Front

LRBs ' 200 • 120 15% •B Recce 45 30 l+5/o SEFs . ' 250 ;.- 200 37fo Fighter Bs 80 56 TSF V " . - - Of0 AC 20 14 lOO/o Coast&l/, ' - - : Oyo

REINFQRCBMBNTS (available initially from areas on the,Western Front)

12, The force shown above would'be subject to rapid reinforcement by serviceable., single engined day fighters only frora other areas on the Western Etont. Dependent upon their state of preparedness, distance away, and to what degree the enerqy were, prepared to denude other Western Front areas of SEF defence,'"""" '':

" (i) The following is the maximum possible on D Day and is equivalent to an increase of 95;£ on the number of SEFs initially available, vide para. 11.

Time No. of A/C. Source Type

1st Light plus 6 hours. 225 FRANCE..,. Low Countries

;and Norths-West GER1CANY • ; SEFs

1st Light plus 10 FRANCE Fighter Bs 6 hours •

Total ... 235 . :'V

NOTE: Some aircraft would arrive in one and a half to two hours while the

/farthest

4.

farthest airay would take the full six, not allowing for any weather or other unforeseen contingency. Aircraft from NORWAY and DENMARK would, not arrive on D day.

The following .is the maximum possible on D plus 1 No. of a/c Source Type

75 NORWAY and NORTH DENMARK , SEFs.

13« Should the enemy retain the "bare minimum in the way of a defensive screen of single engined fighters a more probable scale of reinforcement as opposed to the maximum possible given above, would be about 115 SE fighters on the first day, this representing an increase of k-5% on the number of SEFs employed initially, vide para.' 11.

14. Other reinforcements would be negligible except for an additional 60 SEPs between D plus-2 and..]} plus 7, and 100/155 LRBs between D plus 2 to D plus 14, these latter area. These, together with any reinforcements from second line units or other sources of any kind would only serve to sustain the effort. This applied even to aircraft which might be drawn from other fronts.

REINFORCEMENTS (available subssquently from other theatres) '• "•

15. In addition to the aircraft referred to above drawn from the ' 'western Front aircraft from the RUSSIAN and MEDITERRANEAN' fronts are the only other sources from which reinforcements could be drawn. In order to compare the strengths on the various-fronts, the following table.,, is given showing the dispositions of total GAF first-line operational strengths aft- 1st June, 1943

Western Front' Russian Front Mediterranean Total

• *T Front

LRBs 265 520 250 1,035 B. recce ,, 100 220 . 70 390 SEFs 3 550 460 260 1,270 Fighter Bs, 90 90 100 280 TEFs 525 ' 80 160 765 AC 20 250 -• 20 290 Coastal 70 30 35 135 Five Bs. Nil 280 4 Nil ' 280

X 1,620 X 1,930 895 4,445

16. Under the conditions assumed above it is considered that any re­inforcements from the RUSSIAN and/or MEDITERRANEAN theatres to the V/estern Front would not increase the first-line strength in the face of operations at a high rate of intensity, but merely serve to sustain it over a longer period.

17. Any reinforcements from the RUSSIAN and MEDITERRANEAN fronts must be considered in two parts

i) The movement of aircraft and crews alone without any additional maintenance personnel and equipment,

,ii) The moves of the administrative Luftgau organisation consisting of the necessary personnel and equipment required to maintain all types of aircraft, the supply and maintenance organisation and transfer of aircraft to and from the repair factories and depots in the rear areas.

X X NOTE. This figure excludes 105 SEFs and 15 FBs shown in para, 6 as immediate reserves;

ii) Time

lat Light plus 2 hours to plus 6 hours

5,

18. The degree to which (i) above is possible without (ii) would depend on the capacity of the Luftgau organisation at present on the ¥/estern Front, which if saturated could not cope beyond a certain point without additional Luftgau, being transferred from other areas outside the Western Front, It is considered that the Luftgau on the Y/estern Front is capable of servicing an increase of 50:/b on the present GAP strength in the West.

19. It is assumed that the wastage rate would be such as to keep the first-line strength from increasing once operations had begun at a high rate of intensity. It follows, therefore, that the Luftgau organisation could suffer a considerable reduction in strength before becoming incapable of maintaining existing forces. If, however, it were necessary to reinforce the Luftgau on the Western Front by moving unitL from the RUSSIAN and MEDITERRANEAN areas, it would take several weeks from the MEDITERRANEAN, and a matter of months from the RUSSIAN front.

\

20. If aircraft and crews alone were moved to reinforce the Western Front they would take approximately four days to two weeks from the METDITERRJIINEAJNI front and two to three weeks or more from RUSSIA,

CONCLUSION

21 . The v/eak link in the chain of German air defence in the West lies in the lack of strength in depth rather than in the first line aircraft• It is known that the eneny is making every effort to conserve his strength, increase his production in fighter type aircraft, and so increase his strength xn depth. The scale of effort which he can turn against us xn 1944 will therefore, depend to a very large extent on the degree of wastage that can be inflicted -upon him by the Allied Air Offensive between now and the date of the operation.

DISPOSITIONS OF FIGHTER & BOMBER TYPE. AIRCRAFT AT JUNE L

L E G E N D SINGLE ENGINE FIGHTERS TWIN ENGINE FIGHTERS LONG RANGE BOMBERS BOMBER RECCE. FIGHTER BOMBERS ARMY CO-OPERATION COASTAL

CERMANY

• 0 1

REMAINDER DENMARK & NORWAY OF FRANCE

DISPOSITIONSvOUTSIDE MAP AREA

VLISS (PLUS

SKETCH S.K. If—-/-

20 I IEU WARDEN

• lO

BERGEN

AMSTERDAM/ SCHIPHOL#

" D35

02O) 0 I O TweNTE

^ 6 N S C H e o t * '

_ C D20 Jm D # DEELEN

#SOESfTEf t8ERG

•20 s...;

H30 0 2 5 • 25

• GRZE/RUEN

20 . . . B3P • woensd' recht ' ; # EINDHOVEN 020

#VENLO

• IO - '7MUNCHE N/GLADBACH

MORLAIX

BREST/GUIPAVAS

KERLIN BASTARD

•3 5 # VANNES

CHERBOURG/MAUPERTUS

/ DiO J 0 MOORS E E LE 1

• 5 P-2-5* • COUTPtAl /WEVELGHEM

ST.OMER/LONGUENESSEi f ST.OM6R? FORT ROIJGE

CI • MERVILLE

•50* U L w.- - . . . -

4HO • MONCHY/ BRETON ^ ^^#V«TRV-EN-ART0IS"" % '

• 5 # ABBEVILLE / DRUCAT

025 • ST.TROND

02O • plorennes

32 O. • 25«

^J2Q#SEAUVAIS/ TILUE

0 I O * l a o n / a t h i e s

0 25 # JUVINCOURT

•25» TRICQUEVILLE

335 * CAEN /CARPIQUET

•20_ f B E R N A v / S T . M A R T I N B30

* S • . • C R E I L

B30 0 5-p C# BEAUMONT - LE- ROGER

u« D5 • EVREUX / P AUVILLE

3 2 5 #ST ANDRE DE LEV.

# CORMEILLES- EN -VEXIN *»

5# LE BOURG6T

^VILLACOUBLAV ^ • ORLY

03Ob*£TIGNY #

03O* MELUN

I J Q^CMARTRES

0 20* ST. 0121E R

^20 Jtf IO* WB.NNES

010 S C A LE

IO O IO 20 30 40 50 60 70 80 90IOOIIO120130 MO >50 lj 1 ' 1 I'•' 1 1 1 I 1 l 11 1 1 11

M I LE S 0|O • Ol J ON

c O S S A C / * A

BRITISH

ANMDOJRE III to APPENDIX "K" to COSSAC (43) 28

AVAILABILITY OF GAF RESERVE AND REPLACEMENT AIRCRAFT AND-"-. • • CKEWS WITH' 'NOTES ON REPAIR AND Fi/ilMEWAMCE ORGANISATION ^

IMMEDIATE RESERVES.'- IN-AIRCRAFT AND ;GRElS , . » • :'U:V - •• ^'a--'..

.1 #, . The only aircraft that • can "be considered to have? an-: iimi^diaie;^reservt in aircraft are. the single '.engined fighters*' ''-l&hi's ••is''•not-.;;.(yid0 para 6;) a true initial reserve as the enemy have been forced"-to use' theseair-brift• as'- " first Mine operational ones 'in order'to maintain hi s serviceability, and- present the maximum possible defence against Allied air attacks*: • It therefore, appears. . as. an initial- reserve only, on paper/-and'in fact means that the enemy !s .-first: • line fighter- stx^ength is 20% above normal initial establishment',-' but' still 5/2;.; below initial establishment plus immediate reserve#' ''

2# . The.icrev\r: position is such that- the.'-output is sufficient for present needs* • • . • .

3* The situation Y/ith long range bombers is very different, there being ,.no margin in aircraft, . 'Thus, the first line* strength is -now approximately 6% below. "Initial establishment' and 36^;.below -/initial.; establishment plus 'immediate" reserve# '

if#- The crew- position in long range bombers is:".bad-and is more, of a..con-. • tributary cause to. the weak state of the bomber force than air crafts - -It is considered that at least .on:;the Western,;and-KEB'l!^^ *and probably.'RUSSIAN Fronts, only.30%, of the, ..crews- are fully trained, operationally*. •' >'*

SECOND LINE- RESERVES ' ........ . :

5* The" Reserve. Training Units for; fighters have b.d.en-. given every opportunity at the expense of other types. This., on account of the increased " fighter production and a good'training organisation, contrasts strongly with the'weak position of. the.long range bomber force. ' :

6;. The . number.-of aircraft in Reserve Trai;ning Units is thought to be as •follows:.-.' , '

. ' ; . SEF'.s . ,200-250^ :: / ' • TEF-Vs. 100 .. • LEB! s 500-550 . . .. v

The. single engined fighters - are . in Fighter Pools, mostly located in the SOUTH of" "FRANCE $ ''while, the bombpr- and twin, engined fighters are 1 oca/ted ferther'NORTH i n t h e . c e n t r a l a r e a s • o f . . F R A N C E # • • • • . j . • ; i '

7# Of the above, it is estimated^. by drarnng 011 instructors and the- most advanced crews,,: it-might be possible to produce:^

100 Long. range bombers^ , 60 Single engined fighters*'

capable of undertaking operations. However, their performance would probably be of a low order* . v

. STORED -RESERVES

8« These are thought to amount in all to about 15^ of the. total GAP strength, and. are only .sufficient to cover the amount of aircraft actually being prepared for ,issue to units from aircraft parks or in transit to units* . :

9. In the case of fighters on the Western Front, -there are two aircraft parks, at-LE B0URGET (PARIS) and COIJRTRAI-WEVELGHM (BELGIUIvf) respectively.

v;-::

It is''Wbi^Wfhnt the number of fighters at present in store here may amount to some 75 figlfters".at:%ach* The majority of the other parks are all situated weij into G-EHMilOT.

AIRCRAFT PRODUCTION "• ~

10. .. As shown above, aircraft are going almost" directly into use from assembly, indicating that production is only just keepii^g pace with operational':*!!^ Qlfrher requirements. The position in regard, to fighters is most favourable on account of high priority demand.and maximum pressure being exerted to achieving an increase ih'production,even:;at the expanse of other types., This has resulted in production figures amounting to about ... 600 per month. : The aircraft production factories are all' located; in' the i n t e r i o r e x c e p t s o m e p l a n t s i n t h e S I B M E N a r e a . . . .

11. In view of the weakness in resei-ves any curt^liriBht.,.in a^rc^aft production would soon be apparent in the front line, provided wastaVei,i4©ftiained the same or worsened." -A! •:

REPAIR AND MAINTENANCE ORGANISATION ; ....

12. The necessity for the enemy to maintain the efficiency of his main- v tenance and repair organisation to contend with aoy sustained operations at a high rate of intensity is obvious. .'1 Owing to the weak bomber crew position, the single engined fighters will be the prime consideration as tte . number of serviceable aircraft may well be the limiting factor. 'fphe maintenance of . single engined fighters is dependent upon work carried out under four different conditions:- : <

(i) Squadron personnel

These are mobile and move by transport together with their own unit. During/operations usually they are able only to do normal maintenance. Moreover, . any but minor repairs'have to be handed ever to Luftya_u Technicians. . ,

(ii) Luftgau field servicing units

These are mobile and are used where units are forced to operate away from a main operational base. They are responsible for the supply of bombs, ammunition, fuel and a fair scale of repairs. Normally they are located on main airfields, and a move involves much transport with cumbersome and heavy equipment.

(iii) Airfield commands

The Luftgau organisation itself, is responsible £or all maintenance . and,-repairs that cannot be done as above, for t be, oyxsion of .all necessary equipment, and for arranging that arjjr-with/which they cannot contend are forwarded to front line repair shops.

(iv) Front line repair factories . ; • > ' .1,1 f . ........... ». • •—n. .1

These undert:\ke the production of certain parts and major repairs to engines and airframes..; If beyond their capabilities, the parts have to be replaced or returned to main plants in GERMANY".

13. The withdrawal of over 200,000 GAP ground personnel has made the problem of'supply, maintenance and repair a heavy burden far the. GAP and one which would make it exceptionally difficult for the enemy to maintain a satisfactory, ser/ic". . Vi.li'y if. forced to operate at a high rate'of intensity and under field con3.ition?> away from his main, and well-established bases.

14* No mention has been made of the added complication that would. follow if .any. serious disruption of rail communications were to take place simultaneously with intensive air operations.

15* ' In conclusion it is reasonable to suppose that if heavy sustained attacks were carried out against the main repair f acilities .both, at the operational bases and air stores parks, equipment depots and front line repair factories,, it would have a serious. effect on the fighting value of the GAF fighter force on the Western Front, . Details of the location and number of airfield parks ? supply and repair depots are shown at attached sketch rSK IIIf

G.A.f. flGHT€R REPAIR AND MAINTENANCE f ACUITIES ON WESTERN f RONT

LtGtN D

AIRflELDS IN USE BY GAf.-FIGHTERS WITH -FULL REPAIR fACILITIES

AIR STORES PARKS

AIRCRAFT ASSEMBLY AND REPAIR PLANTS

AERO ENGINE CONSTRUCTION ASS. AND REP. PLANTS

NUMBtRS IN BRACKUS IND/CATf WH&X MOM THAN ONt PLANT IOCATCD

MIL€S MI L£S

BREST

CHERBOURG

S3 IE HAVRE1

l; n i u . j •. us -v BRITISH -

SKETCH SKUI TO APPENDIX ' K'

# AMSTERDAM

t-i.SX** V.-M V-

CRIS NEZ \ \ .

\

r 7

• BRUSSELS s /

•7

v v«—

\. •

A

/I '1

PARIS

7 / > \

• I

v~.«r /

1 /

Vn J

Li La;-:

2 0 0 / 7 / 4 3 / 1 3 S / 1 3 6 C

NANTES

nK!? • ~ ~ t :CQgsA0(43T 28

GAF_AIWlELDS AVAILABLE FOR USENET EKEI/ir JIGHTERS ' .' ' ^ ^ : : / v:;; ...v[F

1 * . / - ev&t' Of. :ah 'attaote^by' Allied-- f©rfaes ::.bn-' theubeacheB; b^tween^rtte COTEM!IJN" ;.ai.bfields which enejuy fighters flight- b.c expected to useidnr:«fleferi.cei of . this, .area are^dfoose J3itft£t;e&\!m^ .,- ,

2# • ' For .the purposes of assessing tho points from tfhich the chief G/a*1 fighter effort could be. expected to materialise^ it is considered that the maximum effort could be. achieved by using only fully equipped bas%%:-,^hould-j . the enemy be forced to- operate from main or emergency landing grounds''"the scale of effort would, be ;bo:und ±';0^?au-f"f-er :u^der.:,t;hefcrst^dlB-. Q£/;o;pe;cate a high rate of intensity? owing to a lack of full facilities*,

3* For this reason airfields have been grouped under three headings; as follows:- ' ;\.l 77: ,77, .

Primary M.rfidofeo;• •• i::!!: nr:,- 77";

i* e#, Permanent bases ftilly eclipped with, maintenance facilities, air sb^I ter s^ .doirivv ix-x1;;

2# Secondary air fie Ids UVC(i os i*£ev*> ^drfielda: :fequipped ' ta/some;. .degree;. Y^ittt.!:faG^litie§^ shut of a ^7,

c ?^ ::Cohsid^lra5:ly:ilower- order^:•.•thahabhose:/;above•: and fy^the#Hor$; Bt&houb.:: • runways* . ' ...... , >.-7

3» Eiiiexp:ency • Landi^ Grounds • , • i# e#, Those vfhipfei" can be used, in cases./of emergency but which have no facilities of 'any aort andvia jwhi^ would. have to be brought to malce .ttem op03ratib^al;;v o:r:rrT, •• l

4-# The f olio Yd ng * ai#fieIds are availabieowithin 110-150 miles respectively of CAEN* . . " •- T- • . ' .. . :-;7; . ;7

(i) o JTJ:v:v •'

: : ' r ' ' r : :• ;Wit hirKTirj Q; miles , - . , • , 7: j'12-^ • .-'P =;• BetY/ee:n.i'.11:0*4,-5Q- files' • , v- r-^-r: .1..

• . . r • Total. * '! 33- '

(ii) ' Prjjgayy, .airfieldg^YAthout runway

Within 110 miles , 4 •Between 110-150 miles . 2 Total Z

(iii) . Secondary airfields

Within 110 miles 17 . Between 110-150 miles 11'-Total ;. 2*8

(iv) Emergency Landirg G-rounds

Within 110 miles 15 Between 110-150 miles 13 Total 28

Emergency Landing Grounds

Mote': These are all obstructed at the time of writing with temporary obstructions which could be removed at short notice. . During the past few months similar emergency landing grounds have returned to cultivation, the total being 85 in EU/iNCE and the LOT COUNTRIES. It is, therefore, likely that the "total of 28 in para 4 (iv) may become considerably reduced.

5. Summary

Within 150 miles of CAEN, there is therefore a total of:-.

39 Main operational bases

.28 Main landing grounds

28 Emergency Landing G-rounds

from which GAF fighter forces can operate in defence of a landing on the CAEN beaches.

6. Of these 38 Main bases there are 12 only which cart be said to have been used continously over the past twelve months as main fighter bases; they are.

Cherbourg/Manpartus S.3. Caen . U.5. Triqueville Q.3 Barnard/St.Martin Q.11. Beaumont Le Roger Q.i! 2: Evreux \ Poix N; 26! Amiens 0.30 Abbeville N.2.

7. Attached is a locp.tion sketch (Sk IV) showing the positions of the main operational airfields, and landing grounds. Emergency landing' grounds are not shown.

J,"

•••'*<•> &

». "-w>-

%•'.. - •• •

: S v - . • . ' ; •

US ™" BRITISH -

• v ANKEXURE V'-tbv/iEP^iX 'it' • ..-•• ~ " : O-GOBSAGIMY^^'^

". EKBkr RDE COVER' ON THE gSTERH MOM1 ,.,

; SKETCH SK V SHOWING- RANGE OE .RDF GO"VER. . *'

' Enemy RDF,cover on the Western Front is'complete:; from ' HAUGESUND in NGRWAI, to the Spanish Frontier®

2$ Such RDF cover is obtained with various-types of equlpnient which can roughly "be classified as follows:- ...

i) .Long .range and short range RDF ;' • ' •

il) .Ship watching coastal RDF..'. • .. -

iii) Mobile WURZBIEGosfrgrt range. 'apparatus- used, by. . . flak and coastal defence batteries for. G.L.-'

3# At the present time changes- are' b£ing brought about resulting in a .strengthening of the chain by the. addition of extra detectors erected "and' further, stations using- new types of equipment -which increases the range and density of .'the...coverage# In addition there are -permanent WURZBURGr sites as well as. mobile sets which have not. been located to date# ~ '•' .. r. : v i - • r - . . . . . . . ' v ; \ '

• 'The Scale of. Equipment r and__Rgplacgq^t^ '

if# : . The scale and'variety of equipment is such that to. seriously impair the system and substantially .reduce the coverage might be a very formidable proposition by air attack* . The- •quantity ' of ijaoblie- sets now • being produced, would enable the' enemy to •• move ..these up. immediately to pover any gap in-the chain. ;

5# :Inland" from '.the coastal .belt there are additional $DF' installations supported by a;-system of Observer Corps Posts , the-latter being linked by landline to control centres.# ... •

6* The •attached sketch (SK: v) shows the maximum range at "which aircraft likely to be detected at various- heights- by long range RDF and ship-watching systems from coastal sites* • •.The sketch takes into account not only definitely known sites, but also those which are suspected on the strength of additional evidence from special'sources* Attention is •'drawn to .-the short range RDF coverage which is. not shown;;this chain is continuous from NORTH DENMARK ..to the Spanish Frontier with a minimum range of 25/30 miles cover along,the whole coast-line, ... ..In addition there are hoardings located at DIEPPE, with further hoardings and a.Giant WURZBIJRGER at BARFIEUR with a minimum range of 4-0/45 miles. The WURZBURGER has been installed recently and it is anticipated that similar stations will be exgcted in the future;, both types of RDF can measure -heights# The minimum range of installations refers to aircraft flying at sea level* The range would increase in ratio to height flovm#

7*, The data used in drawing the contour has included the effect of

"* K * ''' ' *" * 2.

station height and range. In those cases where station height is not known, a conservative estimate has been made,

8« The area between DIEPPE and the CHANNEL ISLANDS includes -2O/3O long range RDF installations, although at DIEPPE, CAP DE LE HAGUE and BARFLEUR, different installations may be located close to one another.

5. It is impossible to compute the number of short range WURZBURGER installations, but all coastal flak batteries would be so equipped, and would be connected by land-line to a Main Reporting Centre. Although these sets are primarily for height finding purposes, and are classified as short range with a pick up of 25/30 miles, the range might increase to 45/50 miles in the case of high flying aircraft.

. . . V 10. The considerable overlap in the sweep of so many long range RDF installations would require neutralisation of several installations, to obtain a gap free from long range RDF cover,

11. The number of long range RDF stations it wou^-d be necessary to destroy, would be dependent on the width of the lane required free of long range cover, and the height flown by our aircraft. If aircraft were to fly in a lano 50 miles wide, the elimination of fifteen installations would be necessary, to make a gap in the long range screen, this would not, however, prevent detection by short range RDF.

12. Destruction of several long range installations would in no way affoct the short range RDF and Alternative detector installations which would continue to function*

13* The enemy will plan the replacement of any installations destroyed by mobile sets which could quickly be moved up to fill in the gap in the long range cover.

14. The en any would require a short period to move in mobile sets and repair landline if total destruction of several installations was achieved, 'During a short period the range of the cover in the area concerned would be reduced but all other installations would be sweeping with extra attention, .. .

Conclusions.

15. In view of the several types of detecting apparatus, no complete . surprise would be achieved by the destruction of several long range RDF installations and the enemy would.be on the 'alert' in the area concerned. This would result in aerial reconnaissance and increasing watchfulness on the part of all personnel in the sector and would eliminate any hope of complete surprise by the main attacking forces.

16. Owing to the number of installations involved and the ease with which they can be replaced if destroyed, this task of eliminating or seriously disrupting this air raid warning system would be a formidable one. The RDF system does, however, enable us to confuse the enemy with feints and diversionary attacks in any area.

RD.f. COVER CHERBOURG-DIEPPE AREA,

200/7/43/ 13 S/ 136 B

BRITISH -SKETCH SKY to APPENDIX*

<3

LONG RANGE R.D.f. SHORT RANGE R.D.f.-"

LtGfND

(fffECTIVf DfTfCTION fROM200'UPWARDS ) (DmcnON ATALL MIGHTSAB(M SEA-lMl)

io6o t=fc

20 40 60 80 100 120 -j I i I I l—J—I I U-L

140 MILES

11'- ^ t'ru >v V-H'SaU'-'p ;?<* a w>«r i

p*--

?

\u

1II1P-I / .

S##!!3!!" S IsM \'.n. v\ m':t:-: rj i"r3 imri} )\ij4jd i:; [ h,~

BRITISH ~.

' ANNEXURE VI ' "bo AMtDIX 'K' to ..C0SSAGri5T28 : . ' V

• ENEMY FIGHTER ORGANISATION IN DEFENCE OF THE CAEN AREA .

(Sketch SK VI - Disposition of Fighter Control Organisation)

t.:: The enemy's fighter defence system is dependent upon:- . ..

(i) Fighter Control System (ii) ' Air Raid Warning System"* • . v

(iii) Airfields within GAP fighter range - • ;

FIGHTER CONTROL 'SISTM • '

2. Fighter control must be considered under two headings: •* -

(i) Strategical control • (ii) Tactical control

STRATEGICAL CONTROL ...

3. This is maintained by a Fighter Command located at. CHANTILLY outside BARISj the Command area covering the Western Front. This Command HQ; .is solely responsible for the strategical control of. the Day Fighter Force. It is worthy of note that before this Command was in operation, the ability of the enemy to reinforce certain areas with fighters in response to allied air attacks, was markedly * inferior to whaj; it is now. , :

TACTICAL CONTROL . / '

k.» Directly subordinate to the Fighter Command HQ»# "are lower formations known, as Jafues, somewhat equivalent to our Fighter Group HQ. These Jafues control fighters operationally .in their allotted areas, thus combining the function of a. sector control and a group PIQ. They can be assisted by local airfield controls at or near the main fighter bases.

5* Normally, the Jafue controls all. aircraft in its area, and the . subordinate airfield controls will only be used for homing aircraft or in the 1 event of breakdown of the main Jafue control. The .Jafue resembles our own Sector Control, except that it controls over a larger area. ,

6. ' GAP fighters are not GCI controlled, but navigate according to a ' map grid which: extends all over Western Europe^ except in HOLLAND, where the control is not by map grid but by vectors '"based on the modified benito system* Since.the introduction of VHP, fighter aircraft are handled, as stated above, by the Central Fighter Control, i.e., the Jafue,. and lauded by their individual airfield controls. In HOLLAND, however, this- does not apply owing to the different system of control.

7» In the CAEN area, the Jafue (Sector) Control1 transmitter has been located near CAEN, but it is thought more probable that the actual HQ and Control Room is at or in the vicinity of BEAIMONT-LE-ROGER. Subsidiary Airfield Controls aire located on or near the airfields of TRICQUEVILLE, CAEN-CARPXQUET, CHERBOURG/M/i.UPHiTUS and GUTANCOURT,

8. The exact. location of the control rooms is not at present known with any degree of certainty, but there is little doubt that, if special efforts were made to obtain this information, they T/ould prove successful in the course of the next -.few months.. The location of the airfields on or near which the above controls are thought to. be situated are shown on., SK vi. .; v #|tv|'i|a!i!l

M . run ifa'

2.

USE OP RDF •&& "•flMWBfrcdfepS

9. The Fighter-Control system makes full use of the available RDF and Observer- Corps brgaiiisation, detail^ of which are given in Annexure V.

AIRFIEIDS. ; : li .

10. - Details of the airfields available to the GAF fighter fbrce and their significance in the CAEN area, are given in Annexure IV ...together with Sketch SK IV. It will be seen by comparison of Sketches SK I V and SK VI, that, although there is a large number of airfields available,- there is a limited number on which the GAP fighter force depends for its tactical con­trol,

METHODS OF CONTROL .AMD FACTORS AFFECTING

11. All control between the various Headquarters, Control Rooms, the Jafues arid main and subsidiary fighter*' station control rooms will be" main­tained by land-line until r- uch time as this is "ho longer possible, when stand-by WT systems will come into use.

12. The land-line system is good and teleprinter network extensive, so that it does not lend itself easily to disruption. - This applies both to operational and administrative communications. This system embraces the RDF 'Luftgau (^administrative) and flak organisation. / . .:

^ OF .CgOTHOli'' SESflBit'' ' :

Disrupt! on of the Air PaJ.d T?amln^ Organisation' '

13. Owing to the number of installations involved and the ease with which they can be replaced if destroyed, the task of eliminating or'seriolisiiy disrupting the air., raid warning fc.yste.ii might be a formidable o.ne. The RDF system does," hovfeVer^ enable us to confuse the enemy v/ith feints and* diver­sionary attacks in any area:.

JAFUC AND-AIRFIELD "FIGHT.Ea1 -QOIOTROLS * ' r..

12f_. With tho present degree of information on the whereabouts of the actual control rooms, the practicability1 of d/3troying- these as a means of xnterferirig" with fighter control canncrc/ at present be assessed.

AIRFIELDS

15» The''iKpdrtaa'jee of the maiix fighter bases as opposed to airfidlds in g e n e r a l i s " t h r e e f ! j . d v . . ,

fa) Tho control of fighter's. as described above. (b) Miuirii^^t^atiVo control,' At the main airfie'-lds are located

the HQs Of AirfieU' Regional Commands, who are responsible for providing the ntecsosory facilities on which the fighters depend in order to carry out their tasks. These. Airfield Regional Commands control the activities of all satellite airfields in thjir vicinityr .v \

(c) Repair and'I:I?.iiitwnsno3,-, -his lias been dealt with fully-in Annexure III;. a^ rofo.-. noo. ::s made to the fact that the efficiency of the fighter force-" is levered- if operations have to be carried out from satellite airfields.

SUMMARY

16. " -The key point a vrhich might bo disrupted ir. order to disorganise the ehony fighter force would 'therefore appear to.be:-

(i) The strategical control centre, i.e. Fighter Command HQa

4-

3*

(ii). The Jafue control rooms• (iii) The main airfields and airfield c.ontrol centres* (iv) Radio counter measures against ground to air .

transmissions from Jafue and airfield controls*' ' (v) Air attacks against selected RDF installations or

technical interference*

17* Before plans for such disruption can. he made further information will be-required on the follow;Lrig:~-<

(i) The exact position of the control -rooms, and their protection* (ii) The possibilities of jamming•

18* In conclusionj it is reasonable to assume that if the main fighter bases and the Jafue controls, as well as the HQ Fighter Command and RDF were subjected to well timed severe and continuous attack these would be liable to produce a state of disorganisation which might reach proportions highly detrimental to the efficient use of the single'~eng;irefighter force as a whole.

f IGHT£R CONTROL

fIGHT-ER COMMAND H.Q... (®)

JAfU* H.Q. CONTROL .....

AIRFIELD CONTROLS.. . . . . ^

MAIN AIRfl-ELDS . . . . ©

JAfUt AREA BDY........ .

R/T V.H.f. CONTROL . ...

R/T V.H.f. HOMING .

LANDLINt ... . ...'.. _L

1050 20 40 60 80 100 120 140

1-1 I I I I 1 1 I—1—1 1 I 1 1 I I Milts

SYSTtM BRITISH —

SKETCH SK3EL to APPENDIX

0

JAfUt HOLLAND

J A+-UE 2

PARIS

OPERATION! 'OVERIORD' US-

LANDING CRAFT AND SHI EPING - PLANNING DATA BRITISH - MMK

APPENDIX 'L'

Serial Type of ship or craft

Average capacities during the "build-up

Round trip in days , to CAEN area

Casualty tables for outline planning (ijor detailed planning see table inAnnexure l]

• .

i .' . . . , -i '

Notes on casualty table

Speed in convoy

knots

Serial Type of ship or craft

Landing craft

carried Personnel Vehicles

(DW-'. tons) stores

With special disembarkation facilities

Without special dis­embarkation : 1 facilities •. |

. D day. D plus 1 day D plus 2 days aha thereafter

• .

i .' . . . , -i '

Notes on casualty table

Speed in convoy

knots

Serial Type of ship or craft

Landing craft

carried Personnel Vehicles

(DW-'. tons) stores

With special disembarkation facilities

Without special dis­embarkation : 1 facilities •. |

.Total loss

Dam­aged

Total loss

Dam­aged

Total loss

Dam­aged

• .

i .' . . . , -i '

Notes on casualty table

Speed in convoy

knots

1 APA 30 LCVP . 3 LCL1(3),

2,000' 150 3,500 5 ) vehicles 6 ) vehicles 10$ 10$ 10$ 10$ 5$ . 5$ ' (1)Damaged ships (excl 1ST) will be replaced or repaired one week after completion .of. trip on which they were damaged.

(2)Damaged 1ST and craft which return to UK will not be available for their next trip but will be repaired or replaced within 48 hours after completion of trip on which they vvere damaged. -

15

2 AKA ~ 6 LCVP 8 LCM(3),

500 200 8,000 4 ; only 5 ; only 10$ 10$ 10$ 10$ : 5$ ... 5$

(1)Damaged ships (excl 1ST) will be replaced or repaired one week after completion .of. trip on which they were damaged.

(2)Damaged 1ST and craft which return to UK will not be available for their next trip but will be repaired or replaced within 48 hours after completion of trip on which they vvere damaged. -

15

5 LSI (H) 6 IOA ' 800 1 ' 1.5 10$. .10$ 5$ 10$ 5$ ~ 5$

(1)Damaged ships (excl 1ST) will be replaced or repaired one week after completion .of. trip on which they were damaged.

(2)Damaged 1ST and craft which return to UK will not be available for their next trip but will be repaired or replaced within 48 hours after completion of trip on which they vvere damaged. -

16

4 ISI (s) 7 LCA 1 ICSty)'

500 1 1.5 10$ 10$ 5$ 10$ 5$- 5$

(1)Damaged ships (excl 1ST) will be replaced or repaired one week after completion .of. trip on which they were damaged.

(2)Damaged 1ST and craft which return to UK will not be available for their next trip but will be repaired or replaced within 48 hours after completion of trip on which they vvere damaged. -

'20 ' ~

5 ISI (M) 6 LGA I LCSQO

800 1 1.5 ' . 10$ 10$ . 5$ 10$ 5$ 5$

(1)Damaged ships (excl 1ST) will be replaced or repaired one week after completion .of. trip on which they were damaged.

(2)Damaged 1ST and craft which return to UK will not be available for their next trip but will be repaired or replaced within 48 hours after completion of trip on which they vvere damaged. -

20

6 ISI (L) 12 LCA 2 LCS^L),

2,000 1 1.5 10$ 10$ 5$ 10$ 5$ , 5$

(1)Damaged ships (excl 1ST) will be replaced or repaired one week after completion .of. trip on which they were damaged.

(2)Damaged 1ST and craft which return to UK will not be available for their next trip but will be repaired or replaced within 48 hours after completion of trip on which they vvere damaged. -

17

7 IX3IX 30 • ' i _ • '10$ 20$ ) If employed on ferrying duties after the assault.See n< below against serials 15 - 19.

jte (3)Repairs to damaged barges and craft employed on ferrying duties off the

•beaches cannot be assessed

8 LCVP 30 3.5 ' -10$ 2.0$

If employed on ferrying duties after the assault.See n< below against serials 15 - 19.

jte (3)Repairs to damaged barges and craft employed on ferrying duties off the

•beaches cannot be assessed 9 LSG 15 LCM(I) - , _ ' ' i

jte (3)Repairs to damaged barges and craft employed on ferrying duties off the

•beaches cannot be assessed

10 LSC 21 LCM(1) -until more is known of r.epair facilities on FRENCH

11 LCI (S) 100 " 1.5 2.0 ' 10$ 20$ .5$ 20$ 5$ 20$ coast. It may be assumed that 90$ of such craft and barges leaving UK will be ,available for unloading first convoys and there­after 50$ will be operating

13

12 LCI (L) 200 1.5 > 2.0 • 10$ 20$. - 5$ 20$ 5$ 20$,

coast. It may be assumed that 90$ of such craft and barges leaving UK will be ,available for unloading first convoys and there­after 50$ will be operating

13-

15 1ST (2) 270 > 60 2,0 . 2.5 1Q$< 20$ '5$' '20$ • 5$ 20$

coast. It may be assumed that 90$ of such craft and barges leaving UK will be ,available for unloading first convoys and there­after 50$ will be operating

t 9

IK LOT 50 10 1.5 2.0 10$ 20$ 5$ 20$ 5$ 20$ oh any one day.

7

15 LCM (1) 4 vfith vehicle 100 wit

. ou€

: " ; I ..

;h-

mm "*

) Craft etiiplqyed on ferry in;.; duties ) . between ship ap.d- shore, assume that ) *90$ of those that leave; UK will be ) available for first convoys of merchant ) Jshipj and thereafter 50$ on any day

1 '

16 LCM (3)

• f

4 with vehicle 60 with out ^

1

L-

) Craft etiiplqyed on ferry in;.; duties ) . between ship ap.d- shore, assume that ) *90$ of those that leave; UK will be ) available for first convoys of merchant ) Jshipj and thereafter 50$ on any day

1 '

.17 LBV (2) 9 2 -

) Craft etiiplqyed on ferry in;.; duties ) . between ship ap.d- shore, assume that ) *90$ of those that leave; UK will be ) available for first convoys of merchant ) Jshipj and thereafter 50$ on any day

1 '

18 LCV • v. :

'4 1 - -

) Craft etiiplqyed on ferry in;.; duties ) . between ship ap.d- shore, assume that ) *90$ of those that leave; UK will be ) available for first convoys of merchant ) Jshipj and thereafter 50$ on any day

1 '

19 LCP (L) 20 < - V

) Craft etiiplqyed on ferry in;.; duties ) . between ship ap.d- shore, assume that ) *90$ of those that leave; UK will be ) available for first convoys of merchant ) Jshipj and thereafter 50$ on any day

1 '

I 2«

Average capacities during the buq,ld-up .

Round trip in days to CAEN area

' ' Casualty tables for outline planning (For detailed planning see table in Annexure l)

Serial Type of Land­ (DW tons) stores

\

With special di s embarkation facilities ,

Without special dis­embarkation facilities

D Day D plus 1 day D plus 2 days arid thereafter

Notes on casualty table

Speed in nonvnv snip OJT

craft ing

craft CfciirixL'

A wJL o UilA.lt/X V UiLLOXUo (DW tons) stores

\

With special di s embarkation facilities ,

Without special dis­embarkation facilities

Total loss

Dan- ' aged

Total . loss

Dan-aged

Total loss

Dam­aged

Notes on casualty table wvAAv MJ

*

Vnrri-20 Medium MT

coasters 112 25 * 4 ' 4 ; 10/ 10/J 10/ 10/ 5/ 5/

Xi.JL l\J O

6

21 Large MT coasters

180 ' 40 4 4 10/ 10/ 10/ 10/ 5/ 5/ 6

22 MT ships : .450 100 5 5 10/ 10/ 10/ 10/ . 5/ 5/ 8

23 Snail stores coasters

300 6 6 10/ %

10/ 10/ 10/ 5/ 5fo 6

24 Medium stores coasters

800 9 • 9 10/ ' 10/ 10/ 10/ . 5/ • & 6

25 Large stores coasters

2,500 17 17 . 10/1 10/ •10/ 10/ — i

5/ 5/ 6

Q U \A t:\ (i \z y [

US BRITISH -

OPER/kTION" 'OYERLOKD' . . AM33SIRE I to iCEPEHDIX 'Lr

. "ESTIMATED CASUALTIES TO/LAMMS' -SH!^

1* The .-assessment of casualties to-landing'ships and landing craft, insofar as it affects the rates of ."build up, has hitherto been based on the conclusion of RAP Opnanittee, :Section WXYZ.. ^This committee*.'Assumed.an overall loss of i*Q per cent of LOT. and 35-- per cent of LST which iDgaoh.on the opening day of the operation, - followed by.'^O'-'ger" cent of LOT and 25 per cent of LST which beach on the second day® Thereafter it was assumed.that there would be .a daily wastage for craft that beached of the order .of 15 per cent ' for LOT. and. ,10 ,]per cent for LST• up' to the sixth day of the operation, . af-fier.: which the. lasses of: LOT would be balanced by the. return to servitje of craft which had "been repaired,., and the wastage of LST would; continue at 5 per. cent,

2* It is. considered that the losses assumed onvthe"opening"Wo delays are unacceptable. . . If; in fact casualties1 on such ; scale .occurred, the.re can be little doubt;thatifthey would indicate a degree 'of -opposition "So-,^great as to lead to the failure of the operation. In these circiafist^ciss ho ' question of a further build up would arise. On the other, hand the subsequent " daily, ratej? of wastage are thought to be on the lov/ it is lassmed that . the ctfaf.t continue to work on: open beaches , whose gradient i& such that in a; great /.majority of cases, the craft will -have to beach and'dry'out. '. It is,, therefore,, considered that, a- drastic revision both of .the method of assessment, and of the., scale of casualties,- /.is necessary* : ;

3* ' The basis of the arguments and tallies which follow is the mxiiHuiti ' loss which can prudently be accepted, taking into consideration the effect on. the morale of the naval, crews. /. It, follows, therefore^ that it will be the * duty of . the force, conrnanders . to ensure,,:.by -preliminary air' and naval action, . that, conditions are -produced commensurate, with, the losses v/hich can be-Accepted*

if. In the first;,place it,is desirable to-divide casualties into two •categories:-*;.. ... •-> :V-\-

(a) Total losses. This would include all.-ships -and, craft:which were r either sunk , on passage,,, or .were so daBikged that theyjwould be unable

. r.to, take, further; piart in the operation. -.i •

Damaged; Thlsr would, include all. -craft which sustain-sufficient • damage , to .necessitate repairs before they could: undertake a; fresh /;/

..trip.f ; . Jt, is, likely-.tMt'most of such damage will be' due to natural hazards rather than to enemy action, and .this will be"particularly the case so long as the craft have to dry out*

5* It is considered .theit the total ; loss .figure, should be taken- as', teh-per cent on the.first ,r.ound:. trip, and s'iffisequently-'at 5: per cent oh each succeeding, round trip, .. Against.-the.&e•^los.aes. mst'expect, to start the operation with '85 .-per cent : of the total: craft'belonging to assault forces1, and. also have a certain margin of reserve craft 'in' .the."- form,-of .-new' eoaatimcjion. It is exceedingly difficult to estimate; at-pre Sent the -extent* Ho which these reserves of craft will be able to make good the total losses. For the time being, however, ,it, is .considered that the following'is a reasonable assumption;-

(a) -The losses on, the. first tri"p will NOT be replaoed before the second trip.

(b) The losses on the second trip will be replaced before the third trip,

(c) The losses on the third trip will NOT be replaced before the fourth trip*

' . - • ?'i j i- •! i j • <•'!! - . ' V"* i fe) I I Ml, \\ \\ |,

• • . • •• y ill w

h i ; : i \-l

i-^ |r if1 i 1 ifl / tiU 1? J4

(d) The losses on the fourth trip will be replaced before the fifth trip.

;;; ,(e) Thereafter it is' reasonable to assume that the total losses ' ' occurring on each round trip will decrease, but not to such an '

" 'extent that they can altogether be made good from reserves and new construction. . For a planning basis it._ is therefore assumed that a net overall" loss of five per cent will occur every third round trip that ia completed. • .

6* Over and above the wastage of the. fqree, of landing craft and landing ships caused by total losses, we must deduct further, figure to allow for craft which .are temporarily daraagecl, (e*g.(b)' of paragraph 4>)

7» , ^'During the first .round tan'ip it is obvious that' the craft will have to use the beaches as they find, thern, which means that a .majority of them may hage to dry out arid may sustain damage through grounding: onitonsurveyed beaches. It is coyisidered that a figure of not less than twenty per.cent of the total will sustain damage in this manner, but this twenty per cent must be calculated from the ninety per cent of survivors referred to in .paragraph. 5i thus involving a temporary loss of, eighteen per cent of £he total available for the. second round trip. Thus the second round trip will": comprise seventy-two per cent of the craft which sailed in the original assault. : . •

8. It.is.probable that the majority of,the craft which have sustained • temporary damage will only-need very slight repairs and given an efficient organisation should only miss one trip. - For purposes of planning* however, .it is considered rjrudent to assume that half of/those which return dgjn^ged »vill miss one trip, and th^ other half will raissr.-, two trips. This assumption has been extended to apply to the whole period of the operation in the table shown in the amexure to this appendix. . -. ..

9. When/we come to assess;the percentage of craft likely to sustain temporary damage, during ; their second and succeeding .trips, an important divergence occurs between the case in which the craft, continue to use beaches without special berthing facilities and the case in which we assume that such facilities can-in fact be made available. In the former case it is considered that the figure of twenty per cent of those which start each trip being temporarily damaged by the time they return to England must prevail throughout the operation.. In the latter case it is considered that an allowance of ten per cent for LOT and five per cent for LST is a reasonable allowance. Two tables.are therefore shown, Table A being based on the assumption that no special berthing facilities are developed, and Table B on the .assumption that such facilities can be made available. ;..(NB: it should be

• noted that the advantages gained from such facilities are not confined .to the fact that slightly more craft will remain in service, but chiefly they depend on the faster turn round that is obtri1" .ble).

10. There is also the question of the amount of rest that will be required by the crews of landing ships and craft during the-., operation^ which on the face of it might result, in still further reduction in the numbers available. It is considered, however, that^this factor cantsafely be ignored pending the production of outline plans, because

(a) A percentage of spare crews are expected to be available*

(b) Bad weather is certain to result in some days of enforced rest#

(o) The crews of craft which sustain damage will also get some rest while repairs are being effected.

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-us. BRITISH

OPERATI ON • "OVERLORD".

APPENDIX !M' to COSSAO Thd) 28

THE RATE OP •BUILD-UP (MM, VEHieLES AND STORES)

.RATE OF LANDING OF MEN AM) VBHICl£ES. , " .

*•1,-. The approximate maximum' rate- at/which me.n, vehicles and-.stores- -could 'be landed has 'been calculated on the'capacities of shipping'and craft-, round trip times and casualties of ships and craft as estimated in Appendix 'lL:|, ' It also takes into account the- limitations imposed by 'beach capacities.

2. ' .Allowance has- been made for a proportion of corps; army and necessary administrative and RAP units to "be . landed to support-and. maintain-the fighting forces, shown "below. These units are referred, to. .as' n overheads ! . Allowance; has " also "been made .for passing of necessary stoipes-. through the " • 'beaches, ' -

Day ""/

fat - ;•

.... .... Format ions, landed.. Day ""/

fat - ;• Assault tb) \ .

.. Pollow-up . k •[ Build-up-." k ,:..(c) . _ fd)

• • ' Running. Total" . ' " .. . Ce'): k= i

D day Three divs

One bae gp of a div# . Three tk bdes#- ' ,

~4 Three assault divs.. • ' One bae gp,.of a ..k folldw-up' -div. •Equivalent of'three tk bdes.'.

D plus .1 Balance of div landing .. on J) day, : ' One 'div* '' ^

.

Three, .assault divs,' Two follow-up div'3* Equivalent..of three ;

tk bdes, •..

D plus 2 - One div/;'

v: ' ' '

One ;di"\4 Three assault; divs. Three. ,.f ollow-up.-divSc

• Equivalent • of --three tk bdesc One build-up ,'di.Vo . j

D plus .3 One div. One "bda,-gp;; . of .a div* ..

. Three ' assault dlvs0 ! Three .follow-up diysj. Eqj'Tilvalent.- of three tk ' lodes o .Two and. .'one-third build-up divs/ ,

D plus 4. Balance' of-'' div land-'ing on D plus Two tk bdes

"Three assault divs, • Three follow-up divs

. Equivalent of five tk bdes. Three build-up divs,

D plus 5 One div# ' Three assault divs, Three follow-up divs, Pour build-up divs0 Equivalent of five tk bdes.

• Thereafter — One div • per day f

NOTE: At least 75% °~ the vehicles on I) plus i and $0% thereafter will be . • landed from MT ships and MT coasters and cannot be unloaded in tactical order. Owing to the time .required for marshalling ashore, the majority of units whose .vehicles are landed in this' manner are unlikely to be 'operationally .available until the day following landing,

it,

3« Detailed planning.may show that from the; naval point of view those figuos can be improved JSlightly J equally it is possible that they may worsen for military reasons<,

SPECIAL FACILITIES

L: * -"'..Ut has been assumed that the vehicles being landed from MP ships and. Iff -ceascovq"will be waterproofed,. so that It will not be necessary for LBV and LOM ferrying these vehicles to dry out.

J-•• She above rattr^":t>een based on the assignation that no •%peGi;al";b:ertM.rig facilities are avalia]51c~Rm the enemy coast, and. in consequence the •' greater' proportion of LOT and LSI will have to dry out on the beaches. If, however /./improvised: .berthing facilities., which will enable craft to unload without drying" "crofc y - 'fee avaiJxujilo, af tor. ../"..plus 36 hours y then the force ashore by D plus 6 might be increased •

°2\I)D:PP-I0WaL; BEACHED ' • S.A ^ . . , . ^ ^ ^ ,

•' • •'•' • • ..The..main'boaclies 'captured: in" the ' i.hitfei:l assault have sufficient thebf etiqal capacity to glands vehicles of''build-up formations and the large quantity of stores requiredal The.dieavy' strain' imposed.-by /themnaay well cause deterioration'in the, benches, and therefore' it is.:considcrSclf es-sontial to \develc»p, additional.'beaches-as -sopn. as possible. »! a'1

•J0: : . .., There are nor ;sM table beaches ' beaches, until the COTElNiTIIT Peninsulais-'reachedoa, •;As..c)nly c or tain •• ^s.tr e t ghbs ;of -'thieatwo 'beaches "which lie EAST of-, the : assault "beaches can boausa:!.a it :.is 'corisidered that both must be secured, pa...;....

8, .......... Before theaei."additlo:hal'"'"":bea0bas...can bo used it wiII be necessary to •• ;neutrali2fe'"oit capture-.ihe enemy defences dominatirig ttrc.au.; The.. clearance of the defences. J near the River -ORKEi. should mt-^aa...diff icult ,3 'but it will bejmore difficult -to.,clear' the CABOURG-d©^ whore" the -defences,.are strong and

:;.•.overlook• the low-lyinggrcn-ind be±:^:e^x-: the River CRF11¥trd QABOuRG-o It ms.ght be-possible^ however <, to 3iuu.-tx-al.lse the guns ""In" rbis -;area.. by naval fire; from the

;asea amd by the use of;medium or heavy aart '.2lory sited within she "br^i.p*eheado

sSIiEITERBI) ¥ATER ' 1 j

'So ' ; The rate of'build-up---4s.,.M.sed on optimum woatjhor conditions. If this ;icate of; build-up is to ' be' achieved^; and, If'Ithe -ferG-Q.-. a&eady landed is to bo .. successfully maintained, ' it Is clear-.that, as there are no ;.cons:Ldra*aole natural areafe .of sheltered water ,which can be/.utilised, drastic stops mustbe -taken to improvise sheltered''^re-4s--..bc^foro the weather. breaks, !

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• -aPEENDIX ' 0' to' GOSS^GlZl) 26

••••- ••QEE&a:iON "'OYSiaGffi11 - ' •'-•••-

•' • -MRBQgRg FOHGEB '- •; ; • • ... GONSIDESLiif-lOMB-' - • - , ^ .....

1, . The decision as to havan. airborne task, farce may be employed yd II be based upovn 'Considerationaof: the'-:foI2c^iiig!'.'fri.otors;:-'

;('a) 'G^ompositiori of "the aiTb-orno-task-•forces- - . ; ' • " *

(;b)'' " ability of; the air force to--lift and deliver- the airborne • force,

Iiiture:;of terrain.-dn thea:fe Jeetive -areas, : : • •' ;

(d) • ability of main task force to reinforce or relieve the airborne troops* •a -:.a. aabaa. ad aa.d. t* • -;;:.«aa a la^,. a a; .. / . •-/ ~ •

'GOMP0SITi-Q-N': OP IiS P0EOE-- • a'a, / a^ a. .. •

2. The airborne. task force available for this operation is composed of: -

one US airborne division, BRITISH - airb-orrie'--cliviS'ion5 ' -a V -a.'-.. .a

; five US parachute"' regiments a- aarj; am . one US airborne'tank battalion*

• and can put into combat a force of officers and men constituted approximately as follows: a......-.,...,--. v am : :; -a. ' aa-- .

Infantry troops 20^440° Rifles , .carbines, pistols^- • '^ub-machlne guns,.machine guns, mortars, rocket

• ;:launchers v' grenade' lauiachersv • 18' light tank ..(BRITISH), ' ffl ' .'

artillery troops 2,696 60 75 inn pack homtsers • oi^equivalent. 114 AA weapons: 20 mm<;a4Q; ^ -5Q£alibcr

: 44 Anti-tank weapons: 6 pcir, 37

. Sngiiieer troops " \ •; o28; G?Mjoot^engirieers-/'ali.g;htl3r: armed,

' Divisional "troops • 1 r; 1, 276 . - •'• Headquarters raid,^.service organisations.

• US 'tank battaliohaa : • d -.aa aa.. •: • , "... ' airborne ' : : ' ''™_300. • ' 54 'T9' -tanks. • •

• TOTAL ' a - ' "

3# It should be noted that due to the" preseiatademand, from the-jiPRIGu-N • theater for BRITISH glider pilots, the BRITISH will not have sufficient pilots to lift their alidor.borne elements;unless pilots -are brought back from the .^PRIC;;J\!" theater 'or provided "for- by an-lriGrea.se in the. training schedule.

.*V :

i^ivIEEICI^•.:•gliaik,• pilots and mechanics are available in sufficient numbers for the • ..Provided- that the necessary glider crews are -made available/

approximately 3*000 lightly armed glider:,, pilots ••apd\mechanics will arrive in the combat areas in addition to the• airborne force* These men are being • trained to participate in.functions of local security., supply and landing area traffic' control.

4* ,1 desire has been expressed, in certain US -.airborne .quarters to' augment', the artillery battalions of tine division with 105 ;mm howitzers to bring -it more nearly to the fire power of the .triangular division, This 'would, probably -mean equipping the battalions with 105 mm howitsers in addition to the 75 m equipment which would" then become '-"alt ornate' weapons, In any events .Hamilcar.- gliders .or their equivalent, would have to be procured for the movement-of the guns and prime movers., (NO'lB: The US 0G-13a .new 'under . service .tests 5 will carry.105 min howitzers, can be towed by -the 0-47.5 and should be available for this operation*)

5* It also appears, desirable to employ three to twelve H-amilcars for the • transportationJ"of "heavy' tractors for the use of engineers in more rapidly repair­ing captured airfields and preparing landing' areas. " ' '

^IhlTY. OF THE AIR FORCE TO LIFT iM) DELIVER .THE EIRBORMil FORCE '

6. . . The ability of the air • force'-to lift and deliver the airborne force depends upon the following factors;- -

(a) Numbers of transports-and/or tugs ' available,

(b) Numbers. -of gliders available- and their .capcicities.

' '(c) Effectiveness- and range of fighter caver*

' ''(d)- Distance between'take-off areas and landing-'areas,

"(e) Number'"' of'' take-off' 'airfields" available *

(f)" Veather.

7# r aircraft have1 been' tontatI¥ely allocated for this operation/ i. e. 442 US 0-47 0^47 aircraft (BRITISH J and 3& BRITISH converted . . bombers,,.No ..provisions have as yet been .made for- f o ur- engine d tugs to pull the Harnilcars "to 'be''employed' by'either BRITISH or US troops* Present'- indications are that ..gliders^will be available .in adequate numbers^ Immediate-steps should be taken' tS""obtaIn a "'ccmjiiltiabnt' oh Ramilcars or their equivalents- forr.p"S ; troops and for four-enginod tugs to pull Harnilcars for both US and BRITISH troops* Present, production figures Indicate: a total' of 146 Harnilcars by the end of March., 1944 and a further 12 by the end" 'of i^pril^ :1944*,-.

8. US requirements -for Hainilcars would be: '

i/p,:/'"".^r3^'.V:i.:EQr. tculk battalion airborne,. ... .

Ty48''''.^ and prime movorsbif'aemploycd* JL2 for engineers1 heavy '"tractor^ at-' -three per -captured airfield,'

T0IAL ••• . ...

If the CG-'~13 glider is used for the 105 ram artillery,, only 80 Harnilcars will be necessary for US-troops*. 30 Harnilcars are required by the present BRITISH division organisation*: 'The maximum number of Hamilcars required is '144 plus a reasonable reserve.. 144 four-engined tugs plus a reserve will be required.

9. The 632 aircraft listed above are insufficient to effect simultaneous lift of the airborne force. Three or more ' shtittle lifts, will: be: necessary, For the" purpose of calculations, 15 per cent of these'aircraft will be.; considered in -operational reserve, and standard- loadings will be used, - Mo.,assessment .has been made, for' operational -l.bs.s-es/ -nhd-it is assumed that maximum '.operational tug- -capacity 'will he available throughout the movement. -When a loss/assessment caij .• • be made, the time required for delivery will he correspondingly, greater unless these losses lie within-the. replacement capacity -of the- operational reserve.

10.- It will, be difficult-to operate more/than one. troop , carrier group with its associated gliders from any one operational airfield. Under .this .condition^ -the" average, airfield wpuld have to-be 'provided-with .additional facilities .'to accomodate thcr large nuiiibors af gliders involved. - "It should-.be'..stated--that., .' within liirdts, • the more departure "airfields, used,,, the'more ; rapid- and -smooth will he the-execution*: .The allotted -pdrcraft comprise 10-g- group's, and would-require a-Kanimurn ';;of. .eleven -airfields,. .Airfields- operating vjacos' .and''Horsae^ should have' 2,-000 yard runwoysv; •- Hamilcar, glider's require '2,000 yards with-1, 000 yards'-1- ^ c l e a r a n c e . ; ; i & ; b o t l i : d i r e c t i o n s . ' ; ~ . \ V r , v . -

11.:; ;-':;The operation can -he conducted-over ah operational radius of 250 miles'... and' 'coEiplyf with''.technical and doctrinal limitations. This makes possibl.er.-.6pera-~-:--tions-from airfields SOUTH of a line 2L1SI and 1EST through WORCESTER - TORTHAMHON,.

12. ..iir operations : in the ar ea NORTH "•iof a lifte.jtlS!£ and :WBST; of ;G0UT4NCES would--be within'range of our fighers, but it is doubtful if adequate air cover could be afforded large numbers of aircraft carrying airborne-:;foK3es.;';:-It is .-;

important to. note,-..that neither.; the US tugs 'nor the BRITISH and US gliders at. present" cSil^'y armour; or oxniainent''.and must depend';'ofi!fighters, t,g ,protect-.them from enemy air ''action' and. to reduce:.-enemy ,grriD'und fire eh' route... .

134,.r; -'--^p^ro:troops can'be delivered in daylight or darkness. G-liderborne troops ;

will probably 'be delivered in daylight only. Pox- limiting -.meteorological : r:;

conditions / see annexure attached. •• V V::

14. It is impossible to determine the ideal lift conditions;Tor; this force;, without knowingthe. ob jectivei and the '-plan'- of the Commander, -.•TWQ:-. extreme conditions Of lift are evident.. The optimum will lie'between the two extremes. These two conditions are: ~

(a.) Minimum lift,where no aircraft towing a glider carries a load.

(b) Maximum lift,where every .aircraft tows a glider and also carries .. maximum pay load, , ;

15. In utilising minimum lift as indicated in 14 (a) above-, • tffo-'and• a half lifts will deliver the parachutists, and three lifts will deliver the glider elements, making a- total of six lifts for the force, .Since approximately eight hours are necessary for one lift round trip, forty operational hours will- elapse between the. initial and final landings.

16. In utilising maximum lift as indicated in 14(b) above, all tugs 'and gliders have been pooled,-and US tugs capable of carrying loads in addition to towing gliders have been partially loaded with BRITISH parachutists. This method simply delivers the force in the minimum time and must o„ccept deviations from unit integrity. It is doubtful that the method is tactically practical without allow­ing tine''for • organization of the troops after they have landed. Under these con­ditions the movement con "be - accomplished in three lifts in an eLapsed time of six­teen hours "

4.

between initial and final landings. The inclusion of Homilcars or their equival­ent and appropriate tugs will not alter this condition nor that expressed in paragraph 14, as the large gliders, are in addition to those used aiid the bomber tugs would, probably be released after the single trip,

17. In addition to the canbat characteristics, terrain must have suitable areas for parachute and glider landings yd thin, a reasonable distance of the assigned targets, ' The areas under consideration iiieet these requirements.

ABILITY OP 1HE Ilt'JEN FORCE xO RE-IKEQRCE QR RELIEVE THE - JSBORI^E: FORCES .......

13. Airborne forces should be reinforced or relieved vathin three dsys and not to exceed six days. It is not mandatory that they be withdrawn from action. In any event aerial delivery of supply in the initial stages is normal and could be comtnericed within sixteen hours of the final landings. Unless landing fields have been put into operation, additional- gliders and parachute delivery units, would be used, ^s soon as ground channels have been established,' airborne Units still in combat should be supplied through them in order to conserve air force equipment,

conclusions : ' • - : v" :

19. (a). Jhe combat strength of the aii'bcfrne-;-force is 540 off icers and men, plus J,000 glider pilots and mechanics, • . • •

(b) With the aircraft and gliders as at present allotted this force, less the Hamilcar borne elements., can be delivered in a minimum of three

; lifts in sixteen hours, and a.maximumof six lifts in forty hours, The 'inclusion of Hamilcars or their equivalent and appropriate tugs will-not

alter these figures. •- .

(c) The operation is within range of fighter cover and can be launched from eleven rj.rfielf'Ls well inlnnd in the uNITED KZHGD01I. '

(d) The-, aircraft allotted core insufficient to allow the maximum effective employment of 'the force. ' . •

OPHIDIC:! 1QVBRLQRD'

MEMEKUM lEiJ?HER REQUIREMENTS FOE 'THE -BEli-IVjjlRY OF .jRBORNE' TROOPS'

to iiNHEXORE

I Q I to CQSguGll5)g.6

3 r-US Location Detail Night Day

¥~ BRITISH

"Night

Over base and| en route *

Minimum Risibility

Minimum cloud, basef above-, sea level) Maximum ' :• amount of cloud

Minimum: moon

miles on ground

5 miles in air

£000 feet

;6/l0 (or 'thin layer)

Quarter

2i" miles

1*5.00 feet,

10/10

2-g--miles.

2,000 feet

2-g- miles

1,500 feet

10/10

Quarter

10/10

u

In the vie- [ inity of DZ

3 miles

20 mph

Minimum visibility •'

'Maximum "wind speed Minimum § "cloud" base | (above ground I . level; | 2,.000,.feet. Maximum amount! VY 4-0 i or a of cloud phDji layer)' Minimum moon f Quarter

3 miles

20 mph - •

1,000 feet 10/10

3 miles-

20 mph

3 miles

20 mph

1,000 feet 1 1.Q00 feet 10/10 10/10

I 1 Quarter J -I «

Yfl'li.THER FOR GLIDER/TUG- COMBlMaTIONS

I \day only) ""EIEFfsir"" (day only) Location Detail

Over base and en rout e

Minimum visibility j' 2-k miles Maximum wind | 25mph Minimum' cloud base _ | 1*500 feet Maximum amount of cloud ) 10/10

In. the . vicinity of

i DZ

j 3 miles Minimum vis ability Maximum wind Minimum cloud base . (above ground level) l Maximum amount of cloud j 10/10

I

25 mph 1,500 feet

2-g- miles 25 mph . 1:506 feet 10/10

ir-11 , 2,5 mph V : 1,500 feet

10/10

*

.aEEENDIX 'P' OPERATION 'QWlBLOia)1 to OO^iC^F^

SKEP^EPOF MILITARY" OPERATION ' BY Kg^STi50E^^PPS*XN• ERtlDE

BASIC ASSUMPTIONS . ' • •' : ' ) " . " l •• ?

iv ' Any estimate of the support which can be-given to• invadirig forces;'by the actions..of organised local inhabitants in • (resistance- groups) depends on'.a number' of factors which will .not be finally determined untllgp day. • • There-. fore? certain assurnptions-miust' be made on which: tbgb''^s# x^xpec'taticj'nSj' as follows

(a) The general situation in FRINGE .wilb'be Substantially the same as that prevailing 1st June, 194-3-*'. ' . • •- V:.- a,...- a '•

' .• ... " . : ' - i K - y _ •• ' '• . "g.' Pa" "j ' "ifh-j

(b);' ;:The resistance - groups, -already.•'•organised on 1st June" will'be maintained about: a;Sg:they/-were" on "that date .and' GERMiiH repressive measures, such as 'the'labour draft, will be successfully countered'#-:

• •(c). The resistance:groups' will.gnp't be called.upon tq\ take:'action.-before • • " D day/ outside :of.. co^trodled' current sabotage, activities*

(d*)..- The necessary material help will be made available t) • carrj out the plans for actions by the resistance groups* \

kGTmm-im isisisfe^ciE:' cm)ups.' ,'Vg- a' ,:-'ga;; gi:. -. :": • :': .g;,

2* . On the basis of: the foregoing . assuiirptionse, -.the. re^'a^^c'.eig-roupB-'-can be expected • .to.:-..support• -military; operations" "b;y" the;• .fo 11 owing'•• actions: ~ £No signif-icance.^should be , attached to' the . order . in which the, types.:, b-f • action are presented)

• (a) • Destruction .of railway,. coiioiuunications , to-impede GERMAN' reinforeement • moves"A' large^nuiriljer .of prepared demolitions' can- be' set' off

simultaneously- to cut all railway' lines running through ROUEN, PARIS, ORLEANS, TOURS, ANGERS and NANTES, thereby • temporarily preventing the arrival by rail of GERMAN reinforcements in the area in North-West FRANCE bounded by these towns i

Railway demolitions can also be executed in great depth as required to meet overall strategic plans. They can-be directed to hindering moves of strategic reserves from the EAST or from the .SOUTH*

(b)• Guerilla warfare* These activities are designed to cause the maximum confusion in the enemy's rear* They will be carried out by numerous small' groups of lightly armed men, and their scope and effectiveness will depend largely on the amount of equipment that can be placed in their hands prior to D day *

The activities will be extremely varied and will include:-

interference with road traffic; . attacks on small enemy headquarters (both personnel and equipment); attacks on isolated small enemy groups, including despatch riders* sentries and lightly armed vehicles; limited attacks on grounded, aircraft and GERMAN'air personnel, including pilots and ground crews;

A

attacks on enaay supply installations.

BRITISH -

(i) (ii) (iii)

(iv.)

(v)

-r

... * 2m

(c) Interruption of telecommunications. Widespread -attacks can bo carried out at a given signal on GEEMaN interior t elecofisnunications by groups specially trained in sabotage*

(*) Aid to paratroops, arrangements can be made through the resistance groups to provide reception committees and.guides .for a limited number of paratroop landings in the interior but NOT near the coast. Special'small groups of trained SO men can be dropped in advance for this purpose where necessary.,

(e) Impairment of movements of GErftLi'l armoured divisions. Attention is now being given to means whereby the resistance groups will "So able to disorganise the reinforcement moves of the local GERMAN panzer divis­ions and mobile reserves by a number of concurrent small-scale guerilla activities of different types* These actions by lightly armed men cannot,' of course, be expected to do more than impose short delays on the movement of panzer divisions.

(f) Prevention of enemy demolitions and preservation of installations. Action along these lines is not expected to be effective in fortified

• coastal areas where elaborate preparations for demolition of bridges and installations have been made by the GERMANS* However, in the interior a number of'bridges and. important installations may be preserved for the forward movement of our troops.

teLr •qpTTPTWTT , Tgjgg"

i'iPPEFDIX 'Q to cosal^M

OPERATION 'OVERLORD'

ENEMY MViJi- FORGES

1•" Enemy no.val forces between the' NORTH of HOLLAND and the SPANISH frontier consist of the following:-

Destroyers «* k~ (These are in or near BORDEAUX)

/ , 1Q (CHERBOURG J, Torpedo do at 3 ...«'*•*•. 12 ^

• ' ' 1 . (I,L PALLIGE ' 5

E "boats* * * **«•»•*#*»«. 45

R boats •*;.».» *'• »«» ** 65

2% .. In addition to the ; above there are numbers of. various armed auxiliary.vessels such as mine sweepers $ patrol craft etc** whose role is not primarily offensive*

AHPENDIX 'R* ... - to COSSAC '(kl) 28

OPERATION '• OVERLORD' •

ENEMY ORDER OF BATTLE *JMD' SYSTEM OF DEFENCE. ' ':: -

. QARENTAN - EXCLUSIVE RIVER DIVES

Order of battle

The sector is normally held by one'defensive division of two regiments with, on its right flank, another, defensive division (.River DIVES -RiVer SEINE)* and on its left, either a second quality or defensive division holding the whole COTENTIN Peninsula.

2'i . The sector,,, which is 45 50 miles long, is held with both, regiments ' forward on the coast, :each having one battalion, in reserve at BAYEUX and CAEN respectively» .Battalions on the coast normally keep three'companies forward, the fourth (MG) company having its weapons sub-allotted to the.rifle companies,

3* little is known with 'certainty of inter-battalion and inter-company boundaries, though forward battalion HQs of the right regiment are at DOUVRES and COLLEVILLE; the dispositions and defence works of the C^ENTAN -3SIGNY battalion (HQ ISIGNY) are, however, known in detail and are typical of the' NORMANDY coast as a whole,.-

Method of defence>

4< Defences consist of beach strongpoints and company and battalion HQ. strongpoints further inland. Strongpoints are number 1- 40 from, right to left throughout the divisional sector and vary .in .strength from half a platoon •" to one platoon, reinforced in most cases with heavier weapons," (usually-two infantry and/or anti-tank guns per strongpoint)., In general, strongpoints are' sited further apart, cover, larger areas, and are less well adapted for'all-round defence than in the strongly held sectors on the Channel coast; • they are not regularly spaced but are sited to ©over vulnerable beaches and. approaches,' Moreover, the number of GAF, GERMAN Navy and artillery strongpoints interspersed between infantry strongpoints is very much, less than in strongly held areas.-Nevertheless, elaborate fire plans are worked out with arcs of fire of weapons within each strongpoint interlocking, and weapons in adjacent'strongpoints are mutually supporting. Alternative positions are•prepared for all infantry, weapons. At night, or in bad visibility, continuous patrolling is carried out betf^een strongpoints, ; ,

5» ' Emplacements for infantry, anti-tank guns and. heavy machine-guns consist of pillboxes, tank turrets mounted on concrete structures and 'TOBRUK' pits; personnel shelters are small and their concrete is three feet thick as opposed to the six feet normally found in,' the PAS DE C«Z5.IS» The quality of concrete is likely to be poor with-comparatively light ^reinforcement» Infantry and anti-tank guns and mortars are often of FRENCH or obsolete types.

6* In- the divisional sector there arej-

One battery of coast artillery 'of two six-gun troops of six inch guns located at OUISTREHAM and PTE DU'HOE respectively,

Two troops of static medium howitzers and six troops of field artillery deployed, ' • .

In addition there is a third medium troop near ROULGATE capable of -bringing fire to bear on the mouth of River 0R.NE,

7« All the normal obstacles must be expected along this sector; in particular nines, sited on the beaches, at exits from the beaches and in fields behind the beaches; wire is almost continuous with gips closed by knife rests. K:

8. Communications .from company headquarters to strongpoints are entirely by telephone or runner in the area in which detailed information is available; there is no buried cable.

CPo'nclusion from study of the defences of the sector

9« The sector is comparatively lightly held by a low category division stretched cut on approximately .a 50 mile front, • The GERMiN plan to defeat invasion,- is •, however, bssod on defence of the large ports, and there' is no port capable of maintaining large forces on this stretch of coast.

10. The GERMANS apparently regard this sector as comparatively unimportant compared with the LE HAVRE; and CHERBOURG sectors. This is borne out by the. fact that the River DIV733 is,the boundary between 7 and 15 Armies.

11. The GFRLS.N defence policy is, however, normally based on counter­attack for the, beaches by panzer divisions held in reserve close behind the coast, and coastal divisions are only expected .to hold out for eight to twelve hours until these panzer reserves arrive.. In tile past, when attack'appeared , possible (e.g.summer of 1942 pant or divisions • were located in the ST 10 VIR3 and in the LISI30X -- LTZIDCIJ - FALAISS areas so that-this weak sector had two panzer division3 available in reserve,

12. The GERMLH Command, therefore, probably appreciates that before an effective bridgehead can be made on the CA23T beacheo and either the port of CHERBOURG or'-cen be ceptured, the invading forces * will be compelled to undertake a hazardous flank march across major obstacles under extremely vulnerable conditions, during which time the GERMAN reserves would be able to intervene and destroy.the forces landed, •

• APPENDIX. ;>S' to-C O S S A C - ( k 7 ) ) 2 8

- OPERATION 'OVERLORD'1

GERMAN FLAK DEFENCES IN' FRANCE ND THE LOW COUNTRIES WITH. SPECIAL REFERENCE TO THE

• CHERBOURG/DIEPPE AREA.

1. Anti-afi»*raft defences in the CAEN/COTENTIN area are concentratedfc*

(i). About the port and town'of CHERBOURG which is heavily defericted,

(ii) The CAP DE LA HAGUE which is heavily defended • .

(iii) The CAEN/CARPIQpET area which is a defended sector because of the airfields there.

2. A tentative estimate of the anti-aircraft personnel in FRANCE and the LOYi COUNTRIES, is about 150?COO, These units sire deployed along the coast in the more heavily defended coastal areas, at airfields and in the more important industrial areasi

The scale of AA defences on airfields, now operational, is heavy, but even Some airfields which are not being used, although not."completely abandoned, have a light AA defence, to the extent of. approximately 9-12 light guns. Over: 100 AA units in grance are fully mobile, while the others require the services of- transport units to move them. The details of which unit is "fully mobile and which is not, are available:/, but will not be. discussed in this paper, .In general, it can.be said that1-under the present degree of mobility, the same • scale of AA defence «an be expected on any airfield from which the'GAF is operating. This would still be the .case should the enemy transfer the operation of aircraft from one .-group' of airfields to another at short notice•

The possibility of employment of AA guns in an anti-tank role'''.must be borne in mind. While the scale of transport is considered sufficient for movement\ in- bulk, of AA defences from one airfield -to another, as. discussed above» deficiency in transport is likely to be a limiting factor to provide sufficient mobility for considerable employment of AA guns in an anti-tank roie't

3* In the event of an Allied invasion, Northern FRANCE would probably require reinforcement in both non-motorised (including railway) AA forces for AA defence and in motorised units for AA/AT work. The bulk of the reinforce­ments would come from GERMANY, Early help might be provided by 6,000 motorised troops from Southern FRAlfe'E, but these would not be sent if there were an Allied threat to the MEDITERRANEAN coast. It is possible, in extreme urgency, that between D day and D plus 7 reinforcements consisting of some 11j000 motorised for AA/AT and 9>000 non-motorised troops for AA from GERMANY might arrive in Northern FRANCE, and from D plus 8 to D plus 30 an additional 13*000 and 3,000 respectively might be added.

"h* There are, on the average, .30 men per section of 3 Light guns, and 8o men per section of 4 heavy guns. These include operational, maintenance and overhead personnel. On the basis of these figures the reinforcements in guns, from the totals given above, would amount to some 2,600 lifeht and 7o0 heavy*

5% See Sketch '3S' attached*

%

•4

$•

s

us BRITISH

APPENDIX »T« to OOSSXdT43l28

OPEE^ION/'

. -:Q:: • OONSlDERiiMta^^ AND , • •: •... IMMEDIATE:3?0£LCfelJP : QUIS'ERffili•mmWMFj: X---. ;

OUISTREHAM,MP- C0URSSUILIL3 (.118798-968857) Beaoh.es 306 ard 3.0?, (6,800 ~ .. , . ... . yards),-

1, . ..:;T . Portion^:;©!""both these "beaches are rocky and only suitable for the landing of .'infantry near high-water,, .With the exception of a. .short each end^ the entire, length of these beaches is /backed "by high sea walls or ver­tical -cliffs*j Theryd^fenses. at. the Eastern,--end; / near the River: ORN3,. are stronger than; elsewhere in-this stretch of coasto Inland,, the ground. rises . .gradually, to" .the open plate.au which lies between..BAYEUX and CAENo . The usuable lengths of,., these ;two "beaches are suitable for. the assault by infantry, but, with the excep­tion of the..^ stretches, at each end, are unsuitable for .the landing of. the vehicles; of the assault divisions,:.

GRAMDC/u.iP TO PTE-.PIT .^OUIN (535936-491900)Beach 315 (7,200 yards) : ^

2, This beach is-very flat except in the "estuary at, the Western end. In the Eastern-half there is an unbroken stretch of drying,ropks,» Any. craft att^pting; to use this beach would be under fire from the O0T2NTIN Peninsula _ unless .the defences .there, had,-beto ;jjeutr.alised(>- •" • • J - . ' -

.. QOmSEIJIlis - ARROMMOHES (967857-8^1-867) Beach 308 (13-'800 yards). ' '

3, Abput 11,000 yards continuous stretch of.,tliis beach''is suitable for ylse by assault .craft, 1 The villages of /\RROilAl)^BrES-LES--BAlNS and ,:/SriSLLES-SnR-MER are.^ :however,.: ;frp:nted by high, sea -walls ,and. there is a ' stretch of precipitous ' cliff immediately EAST of AEROMANCHES0, .Areas' of boggy:': ground' also, limit the movements of troops away fro:.: the beach:-..in twoVplac.es0 , In spite of these _ . obstacles the greater part of this beach|,"which is 'backed by low sand, dunes,,, is suitable from the military,, point pf view^-v.-' Inland, the the B^E^rfiAEIJ;.plat.eau^ ..and is suitable..for the establishment., of beach mainten«r, a n c e . : i ; ^ r e a s . , . r - • , . r f ! * " • ' . • qQlIJIVILIiE - yi!EVlLIiEi/(.;70Q892-638920) Bea£h_313 (8^2,-00 yards) .

4*. . .. . , . .The entire .length is sui%ble for. LGT and: mo.?t of it for LST. . The ' Eastern part ofthis'beach is free from obstacles and tracked vehicles might 1

drive-inland at any points A. low sea,, wallj however, comiiiences about .rthe;;feehtre ! of the^beach.. and. extends along the Western lialg to. the beginning of the cliffe«

- The aj^ea inland ris suitable , for the establishment "of beach"JTiaint.en,"fcbe; areas *

- MINOR BEACHES ' ; 'V V 'V'-" ' * '!

5. .. . Pfhere, are five other small beaches in this sector of .of* Which are rocl^ and . only. suitable for the landing of infantry near hi^h" water,'' They, -may be of gpeat importance, hov/ever, .for landing commandos-/to;a3sist.,,.'the main assaults, '-^-V

SUMMARY

6. Beach 308, plus the Western end Of beach 307? beach 313 are suit---able for the assault,.,

Prom- a study of these beaches it is estimated that one division,; on a two brigade :front, c.ould assault betwee n ST CCEffi ES' ERESNE' (8686 ) and MONT FLEURY (9186) '

A second division, on a two-brigade front, could assault between MONT- 'FiEUBY .-\^d_.BERNIERES (9985), astride the River MUE#

••^v,A';.tMrd division, on a two-brigade -front.., could assault between GOIIMII^ )...and. ST, . ,(6689), both inclusive,

FACTORS AFFECTING ;.T$E JME^W3' FOIMrjO^.: •;

7* .. . ( On the majority of the. beaches in question...LCT cannot discharge vehicles later tfenj-two' hours. -after highwater unlessvthey.dry out* LST in the . assault cannot beach, later than three hours after-high water' owing to the necessity for drying out,

8# In order tjo land sufficient supporting vehicles for the assaulting troopsj without- congiesting the beaches while; fighting is still in progress, the

' initial" assault should-hp .made-, .as long as, possible before, high'water* From a study of the contour's of-the beaches it is estimated that this-.will be about .three"- hours before-high water, for beaches• 307 .and 308, and two hours befpre high; water. for;; beach: 313

3* ' ; From^ the;/alpove it can be . seen that it; will- be^hecessary.;.to land a-very large -"ntM!^-eric>f :;yehicles within-five hours, of the initial assault,

10. '. From a purely naval point of 'view" it is '-possible-to' lattdY&ilvthq '; . vehiclesMift^d;"-by. t|ie-naval assault forces (,2,700 per division) between Z plus 2. and Z plus 7» This would'" uhdoubtedly.' Iead':t6- .a: v§£y.;,ponsafe on' the: beaches-, 'but inv.view o.f the fact that, , owing to tidal conditions^'^it"''-would' be a -further;; six: hours, before .more .vehicles could be landed, a degree 6f: congestion will.have;, to be accepted. ' \ ; • x; -••

11* . The theoretical clearance capacity from bbach 308-- and;- ther W<&steiy. portion •• 6f "•fceaeh 3.07-.-totals 4,-8.00 /vehicles...fox the first twelve, hours, but from the operational aspect it Is considered' that during^:fche_assault/'-hot; .niore. than J'8p;;per;.;cent-of this- o^paclty.-can he utilized* . Clearance,capacity is limited by inland :routes, but- bwihg." to- •••the- large number' of possible beachoexits it j,s .\ ^.conB'iGLered that'-'- 'the full capacity ,ofr4, 8,00 might be used- in-the. second;;twelve 'hoiirs,". - . - '- " T'i"'V:/v.vn

.. The theoretical; clearance!;. capacity fr:om':beach 3^3 is 1,520- vehicles fo the. .fi*r;st• twelve-" hours,, but ;for similar reasons itris - considered .'t-hat:-.;:not more thah'' 80 per cent •-of this can be • utilized'" during the ; assault# •. v.'

13. ,Iir the second twelve; hours it;; is-considered that the full capacity'-of ;--1,920. .vehicles might be used* : . .. - - : -

;14* From the' above it. follows that the'lift' ih vehicles'of three naval .assault forces,-" and about .90 per cent of that in'the two 'naval-'-foil'dYv~-up".forces, . (i.e» a total of about; 12,100) can be landed, and cleared inland in the .first twenty-four hours#. ; "

MOTEr If beach 3^3 was used for landing task forces in -vdaich-'there, were a high proportion of vehicles; suitable for crQ^Srcpuntry"""movement

' .it might" be. possible-to clear more, vehicles on D day#. - * I •

Km:

SUITiiBLB "WEifflHEJR"

' -AKESKDIX 1U* : ; - to COSSAG(^3]28 V

•OHSifJ!iOH 'OVERLORD' --•

' METBQROLOGIGAti CONDITIONS IN THE EASTERN, QEaJMBL;" ;'"'-^ILl;o"'SSmJB!5R •

Eastern Channel is bounded on the V/EST by, the lim-:

PatTLAND ~^tSSSEBOirRG-. '

1,. ..... ... ..Tfoe. terra .'"suitable weatheL " fdr Reaching landingi craft moans any day with winds not more, than force 3 , (9 icnots) onshore, ojnd not" iiiore "than force 4> (13 knots) offshore. I •••}/.. •

. ,| In the c qf tfc /JiiEN 4e°tor, offshore winds, are those between Squtti~East and South-West inclusivet jbut as these winds are. "head winds" for •traffic coming from the SOlfeH Coa^st of ENSuy®, this jtable shaws, the inimbey of

With maximum wind force 3...;4std.additional,• with offshore;,winds ''fpreen^l

Table I

Number of days of wind:-

Force 3 or less Month ^|l^eW*^e's'"i'roiTr^n^^^P1^1'ToinTxTO

years b y . J . years b y ' ;

Air - Ministry -...i-Maval .Met:. branch

M. rmrmmmr

•April •• 16 May; 19 June • ' 2 2 : July 22 August . ; 23 ' .. i September i 19;

' • I •. • ; .

Days pfv-suitable Offshore winds force l\ c1o.vb

weather mean- of colslb

c) plus -col (a) j

.spells' ; - : • ;j_. ' • - ' """; j-

2« (a) A "quiet spell" is defined.as. one with.maximum win&3i^^ (9 knots)#

i' Over' ten consecutive; years thore :'we;re spells for four or more.. consecu~ tive days on the following number"; of: occasions.:-- - •' - '

April-

: Juno July Au.ais t •

. Septernbe r

18 -1 iifies 21 times 19 times 16 times 23 times 17 tiniest

1 2*

Probability of .qUiejb spells

(c) . Prom Air Ministry records from 1929 for Eastern Channel are given:-*

Table II

0 - 1939 " e following iDercentage chances

Month ' Length of spell in days •

': 2 : 3 4 5 6 7 8 9 10

April .3-4 23 r 15 10 1 7 5 . -;5 . 2 • . 1

May ••• 42 30 21 15 11 8 6 5 . 4 June . 6o 51 44 37 32 28' 24 21 18 July , 59 50 42 36 32 29 : 26 24 21 August 63 54 47 41 37 33 28 25 22 September 49 38 30 23 •18 12 7 4 2'

ERE VAILING WIMP

, 3 . The following table, shows percentage of winds of ALL STRENGTHS at .IE HAVRE: offshore winds, are enclosed by double lines:- •

Table III

Month • Percentage of observations from:-

• N NE E SE S sw W " NW Calm

April 15 16 10 6 9 14 11 10 9 May 14' , 14 9 4 1 14 14 10 14 June 22 i 13 6 2 6 12 16 ; 12 . 11

. July 16 . 10 5 3 , 7 14 20 ; 12 . 13 August 9 : 6 • 7 4 9 . . . 22 .22 i 10 11 September 11 .10 10 8 8 17 19 10 7

FORECASTING

4. The chances of forecasting a three days' spell of good weather are about 80 per cent but if 24 hours' notice of this spell is required the chances bee one about 70 per cent. Signs of the breaking of a spell will-usually be evident about two days ahead,

"VISIBILITY

5. Sea fog is most prevalent in May, June and' July (up to three days per month). Poor visibility reaches its maximum in the same months (about eleven days per month).. The risk of coastal fog persisting for 24 hours is small (about 1 in 25)f. and fogs lasting'more than two - three days in any one locality are- vexy rare (about once in every ten years).

us. -BRITISH

. • APPENDIX !V:S operation 'overlord•* to od^mT&T^B

TOPOGRAPH! OP QAEN SECTOR • rive£ dives~tq river virb

(With an annexure on potential airfield sites)

1. This sector is "bounded to the EAST "by tJie Rivers -DIVES and ORNE, ' and to the VEST by .River VIRE, forming a rough rectangle with DIVES, ARSENEAJT, VIHE and XSI&NT as.its corners. The DIVES flows through a wide marshy valley EAST of the ORKE; 'between the two rivers a narrow belt of sand dunes forms the ooastliiie.-• Westwards from the River ORNE the sandy foreshore is "backed as far as • ARRQMANGBBS-by sand dunes, low cliffs, or flat or gently1•rising ground. Prom iUSROMANCHES, cliffs stretch Westwards, to GRANDOAMP, with-' two "breaks in the small harbour of PORT EN BESS'IN and in the COLLEVILLE - VXERVJLLE beach,- which is four^and-a-half miles long. - Prom GRANBGAMP the coast turns South*West towards the. narrow muddy estuary of the VXEE. -

This sector has no coastal plain, though a flat limestone plateau lies between the lower DIVES on the East, and the upper AURE on the WEST, and extends inland for fourteen miles. Otherwise the ground rises gradually, with open rolling country, to the "big hill masses some twenty to twenty-five miles from the ;Coast. Westwards beyond the VIRE the ground drops to the low marshy lands at tke "base of the CHERBOURG- Peninsula; Eastwards, the CAEN plain-runs. South-East to a depth of about-twenty miles, EAST of OAEN the rivers run mainly NORTH and SOUTH thus dividing the area into .corridors.; WEST of BAXE'UX the River A.URE flows into the VIRE estuary a,t ISIG-NT, and forms, a tongue of land -some fifteen miles long, two.; to five miles wide, at the North*»West corner.of the sector. The AURE is a serious, obstacle from TREVIEKES to ISIGNY, a distance of some ten miles. Large areas of the rest of the sector are - Socage* pasture land divided by hedges, blanks and-ditches into many small fields and meadows. In some places the roads are sunken and lined by steep banks.. Movement by vehicles may- . therefore be difficult off the roads.

. The hills of JHOBMANDY 'lie-' to the SOUTH and consist of two main sandstone and granite ridges, which rise to more than 1,000 feet, and run from

.. South-East to "North-West. In-parts these hills will render difficult'NORTH and SOUTH movement WEST of the River DIVES. This country is very broken and irregular in parts, arid the valley bottoms tend to be marshy. The River ORNE and its tributaries cut deeply into the hills SOUTH of CAEN; !bocage* covers most of the area which is well-wooded, several of the forests being of considerable -siae. The dominant feature of the Northern ridge is MONT PINOON, eighteen miles .South-West of CAEN. This rises to 1,197 feet.

RPVfSS. • -

2. (a-) River AURE

(i) NORTH of BAIEUX to TREVIERES; 1 0 - 2 0 feet .wide? .banks. 2 - 3 feet high., muddy "bottom, valley soft in wet weather. Roads across it are slightly raised on embankments. Fording for tracks difficult, but possible at fords marked on 1/50,000 map-. Pording for MT impossible without preparation. (Upper AURE, cix bridges: lower AURE, five bridges,)

ar ;v n f* 5 'f 11

IJ WI ; 1 ^ | | L, 4l

)'"trStXEEES to ISIGNI: 20 - 45 feet wide: 80' feet at ISIGNT. There arc numerous ditches up to JO feet wide. The land is mainly under hay in summer; it will probably bear tanks and MI. In winter it probably will NOTi Any advance across this stretch is likely to be delayed by deliberate bridging operations. (four bridges.)

(b)' River VIRE

(i) Prom source to VIRE: 20 feet wide and less, (itour bridges. )

• (ii) Prom VIRE to BAUDRE, three miles South-East of ST 10: ;;f. 20 - 80 feet wide. (Eleven bridges. ) r:!

(iii) Prom BAUDRE to mouth: 80 - 250 feet wide. (Six bridges. ) • <; All crossings below BAUDRE will bo deliberate bridging operations. '

<«) River ORNE

Prom source to stream Junction SOOTH of ARGEMEAN, under 20 feet wide: the banks are steep, but the bottom is hard> and pan probably be forded. . (Two bridges. )

Between ARGENTAN and CAEN from 20 - 200 feet wide. It should be crossable with divisional equipments down to about ST HARK.D'OUILLY (9834), where it is ?0 feet wide. (Fifteen bridges.)

CAEN to the sea* Tidal, maximum width of 250 feet. A canal, maximum width 300 feet and nine miles long, runs parallel to river. Ground is marshy, with numerous ditches. (One bridge.) • , '

(a) River DIVES

(i) ST PIERRE - SOUSS, tinder 20 feet wide. fhere are several breaach streams, all under 20 feet. (Six bridges. )

(ii) Between HRSPTEVIIIB and DIVES. Prom 25 feet to 106 - 500 feet wide at the t&fcxl estuary. The valley NORTH of MEZIDON is marshy, with many ditches, and is liable to flooding in . wot weather. Deliberate bridging should be practicable between upstream from MEZIDON. (Nine bridges# )

(c) /ill other rivers, in the area should be easily crossable with divisional equipment. * .

WjSATHER (months May,- June and July)

3. Average rainfall is about two inches per month. Rain falls on about one day in three in very; hard sharp downpour*: up to an inch may fall iii a day in May or June, and up to almost two inches in July. On all low ground wet weather will make movement off the roads difficult in the neighbourhood of: the river valleys. Under the same conditions movement in the clay coastal zone is likely to be difficult, but rain will have less effect further inland.

(i)

(ii)

(iii)

3

WOODS

if* The country is fairly well wooded, especially

between BAYEUX and ST LO (FORET DES BIARDS) SOUTH of CAEN (PQRET DES ANGLAIS) area of NORMANDY HILLS (BQIS DE BURQN)

The numerous orchards also afford sane- measure of concealment from1 the ground but not, in general, from the air.

RQAjDS AM) ROAD CENTRES

5» The GERMANS have ordered the upkeep of the following roads, which are generally good, metalled, and at least two-way:-

(a) CARENTAN - CAEN - TROUVILLE ,, (b ) VIRE - CAEN - IiSIEUX (o) VIRE - SP 10 - CARENTAN (dj COUTANCES - ST LO - BAYEUX Co) CAEN - FJJERS ' i (f) CAEN - ARGENTAN

6* Except in the area TREVTERES - ISIGNY there are numerous minor roads loading inland from the coast. Most of these should be treated as one-way roads for heavy traffic.

7» Road centres of importance are:-

ISIGNY, TREVXERES, BAYEUX, CAEN. CARENTAN, ST LO, TORIGNY, FALAISE. LESSAY, PERIERS, COUTANCES, TESSAY-SUR-VIRE, CONDE, VIRE, FLEES, ARGEMEAN.

8. From these centres the roads radiate mainly in South-Easterly and South-Woatcrly directions. \ They are on the whole favourable for an advance Southwards, but their tjjend is rather towards RENNES, LA.VAL and IE MANS then towards PARIS. In the 'bocage' country it will probably be difficult for MT to leave the roads, and much, of the interior is hilly. Cover on the roads varies greatly according to the locality, and is least good near the coast*

RAILWAYS

9- Double track lines run through "the area in an EAST-WEST direction ( CARENTAN.

(a) PARIS - EVREUX - LESIEUX - CAEN - BAYEUX (ST LO.

(b) PARIS - DREUX - ARGENTAN - VIRE - GRANVILLE - C0UTAM3ES.

10* A single track line runs Eastwards along the coast from OUISPREHAM to AIL :Oi.iANGHES, where it turns SOUTH to BAYEUX, and thence NORTH $6 PORT EN BESSIN, a branch also runs from LANGRUNE SUR MER to CAEN. Lines running SOUTH tend to follow the river valleys and, with the exception of that from ARGENTAN, are i:\_.lo track.

INUNDATIONS

11. The following areas could be inundated.

(a) Base of CQTEUTIN Peninsula:- River DOUVES and MADELEINE.

Floods in the valley of River DOUVES upstream to ST SAUVEUR-I^VICCMTE, and over the PRAIRIES MARECAGEUSES and PRAIRIES MARECAGEUSES DE CORSES oould be produced by controllingr-

(i) The lock at LA BARQUETTE and barrage. Open lock and sluices on each rising tide and close on turn of tide.

(ii) Lock at HAUT DICK: same procedure.

(iii) lock at CARENTAN: close lock at all tines unless flooding is organised with River TAUTE as well. (See (b) below. )

In addition, 1,500 yards of dyke, together with locks and sluices must be maintained. Banks upstream could be breached to assist floods; all culverts under CARENTAN - CHERBOURG road would have to be blocked.

Tho result would probably be to produce in sunmer wet marsh with a maximum depth of 12 inches: in winter, an average depth of 30 inches and up to 60 inches in places.

Tine taken to produce this effect is thought to be about fourteen days in winter and thirty days in summer. There is no accurate method of assessing times to attain maximum depth, or to obtain subsidence. Conditions will depend largely on local weather conditions ova: a period.

(b) River VIHE and VIRE ET TAUTE CANAL

Floods in the valley of River TAUTE and VIRE, and the VIRE EE TAUTE canal, could be produced by controlling:-

(i) Locks at HAOT DICK and CARENTAN. Open all locks and sluices of control points Nbs 1, 2, 3 &nd 8 on each rising tide and close on turn of tide.

(ii) ST IHLAIRE PETIT VILLE tide barrier and lock 4038ii5. Keep control points open all the time.

(iii) LB MOULIN BARRAGE, ORMES lock, LA TRINGAIE lode, PGRRIBET CANAL lock, PORRIBET lock and barrage.

Maintain all locks and sluices. Build up barriers under ST HILAIRE PETIT VILLE bridge to hold fully high tides. Breach banks of canal and river to assist floods. Block all culverts under road and railway leading EAST from CARENTAN.

Results and timings similar to (i) above.

00IV:!HJSI0H

12. 'X'hc subject is one of some complexity. The process of flooding is r low .lid cumulative, requiring saturation by many tides, and skilled control of thu . luicoa. If LA BARQUETTE locks and barrage were destroyed, the River DOUVES .voull bo tidal as far as L'ISLE MARIE and the water level affected as far upstream as ETIENVTLLE, In this case flooding would be more erratic, greater in winter, but unlikely in summer.

V

r

It should be remembered, that large porti^s of the two PRAIRIES MARECAGEtJSES are flooded naturally to a depth of 24- inches •between November and March, and ground which has been so flooded will remain an obstacle to MT throughout the year. To turn the marshes into an obstacle to infantry would require much time and labour. All major roads and railroads are built up to such an extent that inundations will not affect movement on them. Therefore, all bridges and crossing sites in this area assume a great importance.

RIVER ORNE

13» Between CAEN and the sea, the canal is 200 to 300 feet wide and the river is 100 to 250 foot wide. The land between consists of marshy meadows with EfenOT ditches, from the sea to the basin two-and-a-hali' mile i NORTH of CAENj further SOOTH, the ground is finner.

Since there are no looks or barrages across River 0PNE below CAEN, any inundation or natural flooding would only occur at high v,ater, and flood water would drain off down the ORNE valley at each low tide. Wascr in the canal could bo controlled from the 0UISTREHAM locks, and would overflow at several points; thus marshy land between the canal and river might be flooded, but it is doubtful •whether this would happen above the basin.

Control of the barrage at CAEN might cause limited sheet flooding of the meadows South-West of the town, which are low-lying and orossed only by €E$>arikod railways. Thus they are already a serious deterrent to MT and there would bo little advantage in flooding than. CAEN itself v/ould not be flooded.

CONCLUSION

14* Artificial flooding of the ORNE valley is possible but even if it were &fifoc$ed» it would not appreciably increase the value of the existing water obstacles •• the canal and river - except at high tile.

DBtQUTIONS

It is known that demolition chamber's exist on mry bridges. Further- , more, in their plan to strengthen all bridges on .through routes in the VffiST to '< $afce a twenty-four ton load, the GERMANS are, at the sune xime, placing desaolition chambers on thorn.

The practical problem of maintaining demolition charges in place, or -ofj putting them in place when needed, and of providing firing parties is so great*"' that it,lfl unlikely that the demolition policy will be ICO per cent effective even on ''routes rationales" and "routes do grande oortraunications"; on routes of lower category effectiveness is not likely to exceed 50 per cent.

These figures are based on. the assumption .that bhe enemy has to withdraw under pressure.

QCUiW^X SUITABLE FOR AFVs ,

16. Ground is, on the whole;-

(.:<) Poor between BAYEUX and ISIGNY, and in the wooded country near F0KET DE CERISY.

("b) Good between BAYEUX ani CAEN. (c) Poor between River ORNE- and DIVES* f .) Difficult in the triangle FALAISE - FLERS - THURY/HARCOURT. (c) Mr SOUTH of the general line COOTAWJES - FALAISE.

6. 17* In the area South-West of the NORMANDY flTT.T^ there are tjo ais^Jor obstacles, except for forest areas. '

18. It would appear that the natural *fcank. runs * are Southwards between BAYEUX and CAEN; thence South-West towards VIRE, and in a South-Easterly direction EAST of the FALAISE - ARGENT AN road.

TERRAIN SUITABLE! FOR AIRFIELD DEVELOPMENT (see Annexure I and Sketches 'SV I' aid 'SV II')

19. Preliminary investigation of the terrain in the CAEN area shows that' thero are numerous sites on which it night be possible to construct one or more landing strips in the area between CAEN - BAYEUX and the sea. Westward from BAYEUX to the River VIRE, possibilities for landing strips beoane progressively reduced. Although detailed examination outside these areas has not yet been made, there is stafficient evidence to show that to the SOUTH aril South-East of CAEN the terrain continues highly suitable for airfield construction. To the South-West, however, extending to the WEST Coast of the COTENTIN Peninsula and towards RENNES, the terrain is very unsuitable.

TACTICAL DEDUCTIONS FROM TOPOGRAPHY OF THE AREA

20# (a) Forces landing between the ORNE and the VIRE have natural flanks in these two rivers, which are considered to be tank obstacles below ARGENTAN and VIRE respectively.

(b) The 'corridor' between the ORNE and DIVES also offers flank protection,,. and it may be necessary to extend up to the EAST bank of the DIVES in ' order to deny observation over the CAEN estuary and canal, which could otherwise cane under artillery fire from the neighbourhood of HOULGATE, EAST of the DIVES Estuaxy. The latter feature dominates the 'corridor1, and would be difficult to attack across the marshy country between the rivers. Capture of the high ground EAST of R^ver DIVES would involve a considerable detour to the SOOTH.

(c) The key positions of CAEN, ISIGNY, CARENTAN and ST,LO as the natural outlets of the sector make it desirable that they should be captured as soon as possible. The importance of CARENTAN, ISIGNY and ST JEAN DE DAYE is also apparent as control points for inundations.

(*) The town of CAEN is itself an anti-tank' obstacle.

(e) •The River AURE below TREVIERES is both a defendabl'e obstacle and a barrier to cur movement towards the CHERBOURG- Peninsula.

(f) The routes into the COTENTIN are extremely limited, and include only .two major roads; this indicates an early seizure of all possible crossings.

(g) The best tank country lies between CAEN and BAYEUX, extending inland from the coast as far as CAUMONP and the MONT PINCON, subsequently expending South-East and South-West.

(h) The best country for airfields lies between CAEN and BAYEUX, and thence towards PALAISE and ARGENTAN.

(j) ITatural objectives are:-

ISIGNY, TREVIERES, BAYEUX, CAEN. ST 10, CAIMONT, VILLERS. The high ground of the NORMANDY HILLS: FALAISE.

(k) Traffic "bottlenecks sire likely to ooour at:-

CAEN, BAYEUX, ISIGNT, CARENTAN. ST LO, VIRE, FALAISE, ARGENTAN. LESSAY, COUCANCES, LA HAYE DU PUTTS.

(1) Tho flank on River OKNE should "be extended Eastwards as soon as possible, and towards FALAISE and the high ground SOOTH of it, so as to free the CAEN area from shelling, to acquire airfields, and to obtain bridgeheads over River ORNE for movement South-Eastwards.

(m) Any movement into the base of the CHERBOURG- Peninsula will probably involve a wide tuning movement, passing SOUTH of ST 10, and possibly between TORIGNY and VIRE.

(n) Any movement South-Eastwards should be approximately between FALAISE and MEZIDON, in the direction of ARGENTAN.

(o) A front approximately on the line of the railway FLERS VIRE * . '• might be held while (m) and (n) take place.

(p) AFVs are best employed in the sector between OUISTREHAM and LONGUES, and infantry in the GRANDCAMP area and between River ORNE and DIVES.

(<l) The natural routes for enemy counter-attack appear to be:-

(i) BERNAY - LISIEUX - CAEN.

(ii) ARGENTAN - FALAISE - CAEN.

(iii) DOMFRONT - FLERS - CAEN.

(iv) MORTAIN - VIRE - VILIERS - CAENv

(v) AVRANCHES - VILLEDIEU - VILLERS - CAEN.

OPERATION 'OVERLORD' to OOSSAP ffifTaffi---

• - TERRAIN'IN-AREA - • ; .

TOPOGRAPHICAL INVESTIGATION TO DETERMINE ; POTENTIAL1 AIRFIELD. SITES . ' '

1* The following investigation, has been made in order 4o;'.. assess the possibilities'of constructing landing strips to be used by fighter aircraft in, the shortest possible time. This investigation was. conducted in two phases «

(a) An analysis of intelligence on existing airfields or.disused airfields which are either,in use or available for use by the • • enemy at x^resent,: .or, which are susj>ected to have been used by the enemy during the occupation of FRANCE*

(b) The examination of complete photographic cover of;the area, in conjunction with existing maps and photographs# to find, areas suitable, for the construction of landing strips on account of their gradients and dispersal facilities, and the possibility of carrying out the necessary.clearance within a reasonable time*

2t Early in this investigation it became clear that the area under exaiaiaation- presented very different possibilities in the Western and Eastern halves respectively, the Eastern being amongst the most suitable for airfield •gons-truction, and the Western of a very much lower grade. Therefore, the yesults of the examination have been.tabulated as follows

(a) Area'A' r extending from CAEN to BAYEHX® .

(b) Area'B* ~ extending from BATEU3C to River TIRE* » '

J# In the following table , the results on the examination as carried out ill paragraph 1(a,) and (b) above .are given and supported by Sketches 'SV 1' and •SVTT attached.

Serial Type of airfield or site ' AREA 'A' j AREA 'Bs '

'e:nmSf: (f una* Wto" •X1WI&1 :

Opacities'

. I ' Main operational aix* «• fields in use#

1

11 ' Emergency landing grounds (temporarily obstructed).

2 • -6 I*U « .

III ;

IV •,

Disused landing grounds returned to cultivation.

Possible site for two landing strips.

16' 1

7 •

32-, . •

w

\:h.

«*•

8

. Y Possible site for one landing strips . ,

15 . 15 -Ji 11 \ 11-'* .

38 • 15 • ' —..

19

2.

4. Assuming that the enemy might attempt to interfere with some of the existing operational airfields and landing grounds in the event of a serious threat of invasion of the area, and that some of the sites selected mij^vt prove unsuitable, a margin of safety has been introduced and from which it follows that the potentialities given above should be reduced by two-thirds. Therefore

(a) In area 'A' the potentiality is reduced from sixty-three to nineteen squadrons.

(b) In area 'B! from nineteen to four.,

5« Attached Sketch 'SV II1 shows the existing airfields, landing grounds and emergency landing gfcounds, together with the varying degrees of suitability for the construction of airfields in areas outside those already investigated, as shown on Sketch 'SV I' attached. Prom this it will be seen that the potentialities for airfield sites are good to the South-East of GAEN, but bad to the SOUTH and WEST of BAYEUX.

POTENTIAL AIRflELD SITES IN TflE CAEN AREA

AR-EA B

BAYtUX

AR€A 'A'

AREA BELOW TMIS LINE AND EAST Of RIVER ORNEM27" EXAMINED fOR POSSIBLE SITES L -E G -E N D

SYMBOL TYPE Of AIRFIELD OR SITE

MAIN OPERATIONAL AIRflELDS IN USE •

EMERGENCY LANDING GROUNDS {TEMPORARILYOBSTJWCHD) o DISUSED LANDING GROUNDS RETURNED TO CULTIVATION +

POSSIBLE SITE EOR 2 LANDING STRIPS A POSSIBLE SITE fOR 1 LANDING STRIP A

IO 15 MIL-E S MILES

200/7/43/13 5/ I36 F.

BRITISH -SK-ETCH SV I TO APPENDIX 'V

C A E N

K^J Li \J lU tbij I J iMan

GEOLOGICAL & AIRFIELD MAP OF NORMANDY

( CHERBOURG-CAEN AREA)

T. 13. gp

CT.II.

10 5 0

I H H t-l H hi

10 S C A L E 1 : I . O O O . O O O

20 30 40 5 0 6 0 7 0 =dI MILES

R.A.F. I, NORFOLK HOUSE MAY 1943

BRITISH. AFI'SIDIXTV*

NONE IN

THIS AREA

GEOLOGICAL LEGEND

Many good sites-good at all times of year.

Many good sites (plateau loam) good in Summer sticky in Winter and after heavy rains.

Some good sites (plateau loam)good in Summer sticky in Winter and after heavy rains.

Sand Dunes, drainage good but few level sites.

Mainly sands but little level ground, danger of peat in places, drainage good when not

spoiled by'iron-pan"

Mixed sands and clays, probably few sites, drainage poor.

Clayey loams-drainage poor, fair amount of level ground.

Heavy clays-drainage bad (clanger of ridge and furrow on Flat ground).

Slates, granite, etc., little level ground and probably bad drainage on level places.

Marsh and alluvium,soft at all times of year.

P A R T

U

ABBEVTkLE

L E H A V R

JROUEN

AIRFIELDS LEGEND

• AIRFIELD. Full facilities with runways.

• AIRFIELD. Full facilities but wi'thout runways.

€ LANDING GROUND. Limited facilities. O E. L.G. Emergency use only.

HOME FORCES N° 57 515/43/277.

fy r " " fF 1 r* i jj

AH I \:J j| |4 ^ ; 4 t,-,u3 r: -v... ii , 6,a i

^BRITISH -US -

*t V- ' •PERATItN ' OVERLORD.

OUTLINE STOKES LANDING PROGRAMME1 WITH BEACH AM) PORT CAPACITIES

ANNEXURE I to APPENDIX 'W to CASSAC(43) 28

Day

(a)

Force landed 00.

Total force,, ashore (c)

Required maintenance

-(d) (e)

Air" forces (f)

Civil affairs (g) '•

Total tonnages ': (h)

Vehicles ] landed 1 '(d)

Beach capacity fk)

Port capcaity ID

Estimated opening date for ports

(m) *

Remarks

(n)

D 70,368 70,368 4,563 4,563 11.535 Over 20,000

Two airborne divisions ashore but not included in troops to be maintained. . D plus 1 44,813 115,181 5,946 1,661 - 7,607 8,521 !l \ )

Two airborne divisions ashore but not included in troops to be maintained. .

D plus 2 50,116 165,297 5,844 2,292 178 8,314 : 9,857 Over

56,000

24,000 airborne troops includ­ed in total troops to be maintained. ^

D plus 3 ; 31,982 221,279 6,776 2,916 178 9,870 ! 5.917 If f

D plus 4 19,514 240,793 7,554 3,724 178 " v - - • • 11,456 i. 3,734 «»

D plus 5 30,493 271,286 8,489 if, 113 178 12,780 ! 6.463 If

D plus 6 25,443 296,729 9,268 1,675 604 11,547 ! 4,779 t! '

D plus 7 24,000 320,729 10,024 1,815 604 12,443 1 4,800 tf A

D plus 8 24,000 344,729 11,108 1,945 604 13,657 •4,800 ft

D plus 9 24,000 368,729 9,932 2,055 604 12,591 . ' 4,800 t!

D plus 10 24,000 592,729 10,551 2,175 650 13,376 ! 4,800 11

D plus 11 24,000 416,729 11,170 2,305 650 14,125 4,800 ft t

n

• ""

D plus 12 24,000 440,729 11,789 2,435 650 14,874 4,800 ft

D plus 13 24,000 ' 464,729 - 12,408 2,555 650 • i! 1 ;

15,-613 '4,800 Over 50.000 •' •' r '

D plus 14 24,000 . 488,729 13,027 2,685 - 690 16,402 4,800 tf ' ~ ; - • • ' ' A

B plus 15 24,000 512-729 12,271 2,815 ; 730 15,816 4,800 tf • ' - ' '

D plus 1.6 24,000 536,729 12,812 2,955 770 16,537 • 4,000 >

tt > •

D plus 17 24,000 560,729 13,354 3,075 810 17,239 4,800 ti

D plus 18 }

24,000 584,729

• ' i

13,897 3,180 8 55 "17,932 4,800 it 2,300 CHERBOURG GRANVILLE

Ports of maximum capacity less than 800 tons have NOT been included.

D plus 19 24,000 ' 608,729 14,439 3,307 900 18,646 4,800 it 11

D plus 20 24,000 ' 632,729 14,972 3,436 946 19,354 ' 4,800 it 11

D plus 30 17,527 808,000 16,805 3,436 1,420 1,000 21,661 .3,505 ti 4,000 CAEN

D plus 40 17,600 984,000 18,423 3,436 1,890 1,000 23,749 3,520 it 7,300 D plus 35 - NANTES Sx NAZAIRE D plus 40 - LOEIEN

f x

D plus 70 4,000 1,104,000 20,920 800 2,650 2,000 24,370 100 it 19,300

!

D plus 45 - BREST, RADE DE,BREST D plus 60 - * T MI HAWS ROUEN.

• *

I) plus 90 3,000 ], 264,000 24,445 800 3,400 3,0OQ 28,645 1,600 1 - '• • '

" 24,500 -4—————•

' .. ; • All petrol being imported in bulk - 8,000 tons per day. .

I©

(a) No allowance has been made

(b) Basis of calculation of to

rrrpr1 .L_ jK>

Jji this table for probable gather interference# • I . * • '

images is attached,. r

h-m & '-""I m

.fir? - .A ;< '1 ''1' n i i__ c >' r • « $ - • S ifrj £

>1

OHIRATIQH * O'VERLCKD*

BRITISH

, /IPB5KDXX 4W!

ADiCQTOfff RAT I'VE CO?EIDER/>T 10?fe;

PART I « PREPARE I0.N

Availability of Ui;; administrative unit 13

1, (a) Headquarters BTOUSAhas determined ' .an-iorder qf 'battle for US fore&s , ! among--which are listed, all US administrative; units required for th© operation. The order of .battle is>'-ourreiit2y being sent to the War Department. " '

The availability of the necessary US administrative units to provide adequate support for a force of the basis type and sis© ; contemplated in 'this paper depends 'in part';upon the following:-- '

(i) The. numbers .and types of adgilnistrative units sent baok":fraa . . NCRTH AURIGA'with the four divisions due to return to UK Mir

November, December and Jahuaiy next* It seems hi$i3y" probable that, a considerable number' of*; auxiliary administrative troop®

••••. will- be included but not a sufficient' number, to approxia&te balanced'US divisional slices of 45*000,

; . ( i i ) The •nur . ibe*rs r jad. ' J fcypes of adminis t ra t ive "uni ts iJOGOssaay to activate.. inmediAtciy so as'to make up the Tewa&n&er &£ tl» •

. administrative units re quired consider^** that these dugji I®" properly trained,This is cur;reh't2y .being studied atW'W.'" Dc piirtment .-.levels,

(b) I f the re quired. : \%'dmini is t ra t ive. ; . . t roops are to be provided, ear ly decision at War Department 'level"' is necessary; first as to the troisp®

"to be provided from those in^i^^^HXCA -and second as to the ; ..... of providing the remainder. It rKy-.be^ebessa3y -to oannib^lise

existing grounds-forces. Early decision is necessary,

Avod.3xtbili.ty of '.BRITISH aAfelnistrativs units • ; ' • /

.. ..provide a .baliui^M'^caroe'.-jof .the- siae ...cpntemplated in the paper" depends upon;- ^, "

( i ) The numbers and, types of adminis t ra t ive .uni ts sent baclc f roa NQKSIH A1®ICA with the three divisions inr. November of .this, year. Instruct.iohs have been sent from War Office to BHA3P that balanced divisions of a strength of 40,000 will be. retursied*

: .-(ii) The extent to.-fthidh adTiinistrative personnel can be .obtained from AA formations, ;:-."'-:In'-.this.jsomiectjUsri .&'!$£lic(y"' decision is awaited*

(iii).., ;5?he extent to. which use can be made of-vpaxaHmilitary organisation, . .. /This 'scheme is being..examined.by the^ Adjutant General in oonjuno-

, , tiph with the Ministry, of Labour but.^.de^snds' on whether or not the . . . , Army can obtain the personnel/over arid5 above its normal intake.

Even if the administrative units . expected; from K3RTB AFRICA materialise some cannibalisation involving the abolition of not .least thaa owe fighting division may 'be necessary.

e necessary H03?^Bt;'^dndiii^trative:5:tmi^v'to

f" W* ll

2. 4 JL» early decision is. essential if cannibal is at ion is to produce

administrative units, fi'6 to operate in battle conditions by 1st May, 1944. This poliqy decision.cannot be taken until the operational basis necessary for the production of afa.outline order of battle is prociuce 1,

Availability of material \

3« The requirements for. development of ports and discharge facilities are now being re-examined, - .Apart from the equipment required for this purpose, no serious bottleneck^ either BRITISH or ITS, in the provision of any cla.ss of stores can be foreseen, providing, the shipping situation does not again deteriorate, . ;

Evacuation of wounded •'••'. •r—. . — —

4. No definite plan at present exists for the evacuation of wounded during the assault; The numbers to be evacuated are provisionally estimated as follows:-

Oh D day On D plus 1 day T<!)TAL D a Ed D plus 1

Unless suitable ships and/or craft are earmarked and adapted where necessary for this 'purpose, adequate provision for medical evacuation will not be possible by 1 st !May, 1944.

P.fiRT IT- - MAJffilENMCE

Rate of build-up - jmen and vehicle s '

3* Rate of build-up of lodgement force by divisions is shown at Appendix ' M*,

Rate of build-up "istores

6". Annexure il shews the estimated tonnage of stores required to 'be landed daily, compared with the beach and port capacity over the build-up period, ,

Maintenance over bgaches

7* (a) It will b;e seen from Annexure I that the 'maintenance of the f ores during the initial stages requires, a coittiriuous flow of stares (including jainimtiHi reserves), rising from 10,000 tons jer day on D plus 3 to 15,000 tons on D plus 12 and to 18,000 toons on D plus 18, During this period the build-up programme involves the landing of approximately one division a day.

( b ) T h e t h e o r e t i c a l c a p a c i t y o f t h e b e a c h e s i n c l u s i v e I S 2 S N I t o i n c l u s i v e O'UISTEEHAM is 'sufficient both to maintain the forces ashore and to land the division a day until about D plus 12 when the operational plan 'should permit the development of further beaches to e. flank* Thereafter the total beach capacity will be sufficient in theory for •the 'maintjenance of •••'the initial lodgement force (about thirty divisions}*

lip-

5,500 4? 500

10,000

Sitting

5,500 4,000 9,500

3.

Maintenance - ever-the beaches is., however, subject 'tq • interruption fay bad weather,. The meteorological examination shows that it will be difficult to forecast a period of fair weather of more than four daysj

.. . it f ollows that from D plus 4 onwards our maintenance plan must provide., ' •'for the fact that on some days beach'Matinenance:-will be impracticable>

irpreliminary examination shows that^ito provide foRthese' •' interMptions,;, it would be mde's&axy-'j in the early stages, to increase the daily tonnages to be impacted on the operable days.by some 30 per

• centi .. . .'•••' ., ad- ./'

•(c) The movement arid distribution difficulties inland,, inherent in, mainten­ance on such a large scale'without-i^crts and. for: so long a \ period, will be grea.t, "'The exact effect on the'operations cannot be .deternjined without detailed examination and. praictical experiment: but a.-:

investigation indicates clearly that^;- while we-'might be able, physically,, to land the above tonnages increased by the 30 per cent, it would not be practicable to distribute these vast daily tonnages to the depots and thence forward to the troops within the ;somewhat . • restricted area of the bridgehead. Therefoi-e it will be hecessaxy-tlp have facilities for discharge during bad weather so as to reduce the 1'

" •. peak loads over the beaches on the operable days an3. to even out the ; flow of traffic through the maintenance areas,: ;vi.<

(d) Uncertainty as to the incidence, and duration of the spells of bad weathSr and as to the exact limitations mposed by the -dj^stidbution problem ashore makes an accurate estimate, impossible^ .but it to considered that the minimum- facilities required .for •: discharge. . uninterrupted by weatfcer are'as follows;- ; •'• •

', I) plus 4/5 ' 6jP00 tons per :&ey :

D>:p3iis 1-0/12 9,000 toas per day Iiy D plus 16/18 12,000 tons per day .

' • The. extension'of:^t he bridgehead envisaged in paragraph. 104 -of Part XI dees not /include the early capture af GH3SB0llE&» ...Moreover, the • estimated capacity of GHERBOUIfi-; group of ports will, be' wholly ' • insufficient for the maintenance of the lodgement force', . It follcws, therefore, that additional improvised sheltered ca^eity will; be •;

;. .necessaiy in any case and that its early provision" is essential to m&b •••. ••""'•^t'he. initial- maintenance problem,, - Expedients to' provide-,' sheltered

''^arichorag^s are 'now under- examination, • '-

.-taint cno nee: through ports •

>V -: ''The operatioiial plan;'should provide for the.-early Capture, of parts so ;h.ut • TiB'and: ;SlriaH lincss of coimnunication. -megr ...be. developed-from. separate ports#

(a) -Bulk petrol '•: y:r .'

It is reasonable to suppose that'by D plus / 9& ths t otal petrol tonnages /'or the lodgement, force, will be put ashore in bulk by various methods, •'iiid will: probably amount to• Sy000".tons a day* :-

.- Emergency measures • v./.-..--; •• ^x-:

It is'-possible that plans, for the improvisation of sheltered waters m&*? mis-carry' or - their, execution b'e delayed by :enemy action or unforeseen difficulties# If this oooutfs, the existence of the forces landed will be in jeopardy should foul weather intervene before ports or sheltered 'waters have been developed or airfields captured*

To meet such a contingency,/ consideration .should be -given to the . p r a c t i c a b i l i t y o f t h e f o l l o w i n g m e a s u r e s ,

4.

(i) Special ships ..

Holding a number of medium sized store ships,, sstowed with cai*go essential to maintain the existence of the fcrce, in readiness

• ; .i to be driven, ashore and beached in the last resort,

• (ili) Air transport (see Annexure II)

It is estimated that from D plus 2, for periods HOT exceeding three consecutive days, estimated available air transport should

V :'L be abJfi to provide a minimum lift a£ 2,400 tons cf stores a day. • These emergency lifts cannot be repeated until either the'gliders

used, have /been retrieved frcm the Continent or replacements ' obtained from US.

Sfoscial re quirement s .

10. (a) Air forces

A provisional estimate of•requirements for air forces is included in • Annexure I. 1

(b) Civil affairs

(i) No shipping space for civil affairs tonnages can be relied upon • during the assault and follow-up periods,

(ii) Initially it is ejcpected that oivil affairs requirements will be of the order of one pound per civilian per day in the area of occupation, ;

(iii) In the more advanoed stages, when ports are operating, the tonnages which must be made available to civil affairs will

' x increase owing to greater commitments.

Summary of conclusions -I'­

ll* (a) Oh a theoretical assessment of import capacities- the build-up of the -lodgement force can be supported over beaches until the part af :CIEKB0IJRG has been opened,

(b) In praotice, because of interruptions by bad weather and the reception and distribution difficulties inland from the beaches, improvised sheltered waters must be provided early and it is cons-idei«d that the niiniiaiLim facilities, required for discharge, uninterrupted, by weather, are ais follows:* . . :

D plus 4/5 6,000 tons per day 7 D plus 10/12 9,000 torn per day -:.:r

I$y D plus 16/18 1 2,000 tons per dsy_

(c) There has been no experience of maintenance over beaches and try other improvif d metht s on a large . scale and..f or long periods. Such methods will inevitably be expensive in ships, Graft and material of all kinds. Moreover, in the autumn and winter, beach maintenance becomes entirely impracticable. Therefore the earlier the CHERBOURG-group of parts are oaptured and developed the better.

% Maintenance areas

12. (a) Topography

(i) In the area OUISEREHAM - CAEN - MEEUX » MROMAJNTCHES there is • little (xrresc: - and near the sea the ground is generally hilly*.

„ Minor 3|oads are principally one-way and road circuits are poor.

(ii) In the area B&YEUX.- ST LO - ISIGNY there is good cover and good road circuits. However, the valley of the River AURE from ISIGNY to TREVIEKES and the ISIGNY watergap might be a -considerable, obstacle in the event of the bridges being demolished,

(iii) The towns of CARENTAN,' BMEUX and CAEN are considerable bottlenecks. .

(iv) There, is only one first class road leading from COTENIIN Peninsula, and this passes through CAREMTAN.

( v ) Conclua ions .

• ' The existence, of the bottlenecks and streams, referred to ab.ove and the shortage of two-way roads will complicate, the selection and development of maintenance areas.

Lines of coiirounication

13. Because of the differences between US and BRITISH systems of supply, separate lines of communication should be developed at the earliest possible date;" ideally from the veiy beginning.

14. Since no reliance can be placed on rail facilities before D plus 30 at the very earliest it will be necessary to maintain the forces ashore by MS during this period. Employment of this means of transportation will necessitate confining the lines of communication to a maximum length of 1.50 miles unless, due to a less comprehensive; or less weU executed scheme of demolitions than must be expected near the coast, lengths of railway line further inland are captured intact, together with the necessary power and rolling stock. In this case, the maximum lines of communication will be 150 axles plus- the length of railway captured intact. :

ATTACHMENT-to AMKEXHRE f

to APPENDIX !W

BASIS OF CALCULATION OF OUTLINE STORES TONNAGES i RESERVES POLICY . u

1, 14 days', initial stocks to be landed "by D plus 41 for the force then ashore* -

3 days.' replenishment at current rates of expenditure "by D plus 5 for the force then ashore,

BASIS 0-B1 CALCULATION -

Supplies '

2, 5 lbs per head, per day.

Water

3, 1 gallon per day per man landed on D day and D plus 1 (other than wounded).

2 gallons " " " " " " " '' " " " M (walking wounded), , 9 gallons " " " " " " " " " " " " (lying wounded)*

POL .

if» 1 gallon per. day per motor cycle. 5 gallons " " " carburettor, 50 gallons " " " tanks

Ammunition •

5» D day to D plus 8 - double intense D plus 9 to D plus 12+- - intense

Thereafter noiaal with one day in seven intense,

Oixlmnce ~

6. The BRITISH calculation is based on the weight, of lauding, reserves and "beach maintenance packs and the .AMERICAN basis is 10 lbs per head in the assault and early 'build up'period, thereafter at 8-g- lbs per head#

RE (including airfield construction)

7. 1^625 tons divided.' between. D day and D plus 1j thereafter 200 tons per day per division landed.

Airborne forces - -

8. Two airborne divisions to be landed on D day will be self"Supporting until D plus 3* Thereafterj assuming both BRITISH and US airborne divisions to be 12^000 men each, an overall allowance of 50 lbs per man per dayi.has been ma&$%

• Air forces

S:« The figures are based on RAF estimates to cover total requirements for air forces ashore, (USAAF estimates are still under consideration,)

Civil affairs

10, No civil affairs tcarnage is shorn before D plus JO, I,t is considered.^ however, that small tonnages may be landed for civil affairs • from £> plus 6 onwards,

MNEXURE XI to APPENDIX 'W'

to C0SSAGr(Ii3T 28

OPERATION "OVERLORD'

IMPLICATIONS.OF THE AIR TRANSPORT OF STORES

1* Consideration of the ability of troop-.carrier aircraft and gliders to deliver supplies is dependent upon:-

(a) Number of aircraft remaining operational after the delivery of airborne troops.

(b) Number of gliders available*

(o) Weather conditions,

2» No accurate estimate can be made of the actual number of aircraft' remaining operational after delivery of airborne troops* It Yd 11 be assumed that 300 'of the 632 allotted will be available*

Following the. delivery of the-airborne assault force as outlined in the Outline Plan for Operation 'OVERLORD1, 2'JOOON gliders should be available for further operations;' Two. conditions for the employment of these gliders will t h e n e x i s t : - . . .

(a) 900 gliders must be held for the delivery of the airborne reserve^ leaving 1,100 gliders for use in supply missionso

(b) The airborne reserve is not employed, making available the entire 2,00.0 gliders for the supply missions«

h.e (a) With the 1,100 gliders and the' 3^0 tugs, supplies totalling 2,200 tons per day can be delivered on two consecutive days beginning D plus' 2, provided the tugs released from the obligation of delivering the airborne reserve, or, beginning twenty-four hours after the reserve has been delivered.

(b) With the 2,000 gliders and 300 tugs, a rate of'supply of 2 >400 . tons per day for three days can be maintained commencing with •• D plus 2*

(c) Figures in sub-pair as 4(&) atid 4(b) are based on 300 tug/glider . combinations making two round trips per day at four tons per trip#

(d) No provision has been mada;,for the 're-supply of the airborne assault forces as they will be delivered with an initial supply for three days, and it is assumed-that their re-supply require­ments are being considered in the overall supply operation*

-L is believed that conditions of wind which would disrupt seaborne supplies would have associated weather which would not materially hamper airborne

vol ..uOo aei inite Xdxwating factors are that the operation should be conuuoted in daylight, with a ceiling of at least 800 feet ;above .the terrain,' ml visibility of 3,000 yards*

Necessary .ground organisation for the preparation' and loading of supplies at oase airfield is imperative, and air superiority over the route and. arc:::, of delivery is essential.

I uy. fi p:i. L-M M##l I iLi

' us '-BRITISH -

.\'.-U--,'..- , OPERATION OVERLORD'. APPENDIX 'X' :Mx30SSA0(43) 28

Iffimoife FOR IMPROVING-. I)ISCiil4RG-B FACILITIES...ON T1S,FRENCH COAST

1. This problem is discussed in general.in paragraph 39 of Part I and in • more detail:- ;v."; ,.r , ..v.. •

. " ..(a) From ti\e.MT aspect in paragraph 83 o.f Part II.* . . •(b) From the stores' aspect in paragraphs 1.10-113j' taiH; II, and

... .Appendix ..'f.'. ^ .. '".a.

•2« A re-assessment of port capacities is being made under the direction of the .Principal Administrative Officers, (GOSSAO/3003/2/iloy & Tn of 21st June refers)> .and there is little doubt that , this will go some way to ,meet the deficiency until enough major ports are. available.

3« . T& examination of. possible methods of improving'discharge facilities can ooiiveniently, be divided into, .two headingst-

A - Improvement of the open beaches for use when the weather is , favourable. , - ... •

B - Iinxorovisation of sheltered water and ports for use when , the weather-is unfavourable. '

A - IMPROVEMENT OF THE OPEN BEACHES FOR US£:WHEN~~#SE- WMTHBR IS; FAVOURABLE

"Pi BcharAe points .for MS . ,

4. - Five ciischargiiag points are required to be establishedr-on open beaOhfp in the vicinity of the original, assault beaches within 36 H6^s of the first jlanding...' Each point should be/.capable of. haaidling the ships : and craft per ijUjy:- •.,., . .. ai;a:^'^a*:'. ' ^ ;

a . " . 80 LOT - 1 " ilT

150 lcm : "r . ' 50 lbv "

. -5,. ... ;The beaoh...gra^ent,.at these five, points Mist in no case be flatter : ;±kvn. ofiu' ip.-q..,. "... "'

5..,; will be sufficient to deal with all LST 'and' LOT 'arriving • daily.*"'- -TKey-wili &ll6w'm.sohsirge'-at'all'-stat'efe of the tide, v/ill improve, the turn round of craft and will decrease the casualties to the landing ships and:craft, so that the rate of build-up can be maintained or erven inqreased.:' • • •'' " "••.•• -a. , .

Lighterage -ports for • s;tores , f' ' ""'j . /

6» The following areas shovfld also be davelc^ed as unloading points to which stores could be taJcen ashore by lighter from tetore. ships at anchors-* .

. , (a) OAPELLE road, off. GRANLOAMP (491900)

-aa'Developing between PdlNTE-ro :,G0OUIN and confluence of VIES.-and AUBE Rivers as unloading points .for.;.lighters. - . .

Cb) Off CAP G^iRTERET (990930 in South-West of COTENTIN Peninsula)

Using CARTERET as an unloading terminal• .

• I vS llD Wsiu e it Si •

33 - IMPROVISATION Off (SHELTERED BEACHES AND PORTS FOR USE WHEN THE WEATHER IS-. ' l ~ . ~ ~ - r — • — •

? • • -raa-'-draey' ;tp~' provide shelfcered wa-ter that will not be subject to. inte" caption ."by/the weather proposals-are made in the following:

Sheltered'"beachep - mechanieal' liyansport* " •

8.; (a) Three' selected areas of beach should be specially developed, :

including the -provision -of '.A& prdteotion, for the landing of MT.

< (b-);: The following positions' are suggested as affordirig;.,alternative' . . sheltered benches:-• -v.--. : ':' - h;''

(i) .Abreast (972243 to 978226 in North-ffest of OOTENTIN V , ;:;;-r/Peninstila) o . '''•'> • KOliil of QUEEQIIEVILm (082270 to ;086269 ih I«RTH'of OOTENTIN '

Peninsula) *. '' ' ' ' • • ?0Ud,jaVIIM»%(; 5®2i;.; to '420014 in South-East of COTENTIN

' ' P e n i j H s i i l a ) 3 — . ; ; " : "Itwill-be observed that ©ne of these three beach areas will at all,.-

times be sheltered except from winds, ;~in;'the'- direction North-North.-- West. . : .. ; .A • - •

(0) 'Each.of these three areas must be.madercapable of handling its allotted quota of MT depending on. the' prevailing weather conditions. Arrangements 'pi/ill.probably be necessary to transfer labour'!ahd' .Equipment from one beach to the other as necessary,: or to have, additional'labour and equipment if it is found impracticable to effect the necessary transfers- without delaying discharge. . , "

(d) A disadvantage to all - thesd!,benches "is "that clearance from;.;them'must be over.the gkme -roads that are being used for the clearance of CHERBOURG. | •• • ;;

Artificial -ports r stores '• '•

9» "The,cpHstruotJcm/ of.tw;q artifi;diaT':;ports is required-as early as ' possible. It'is. su-ggefeteid that one of these might be made in position 49 21' NORTH, ''WEST (8 5870, North-East of BAXEUX). The suggested method of achieving this is indicated in the annexure to this.appendix, from which it will "be seien that a total of some 19 block ships and four-piter ships for the one port will have to be prepared and subsequently expended for this purpose. It is . estimated that the ultimate .receiving capacity of a port on these lines would be . of she order of 6,000 "fxms which .is equivalent to,,the .maintenance, of .ten- divisions, though the actual rata;of clearance niight be inuch less in this particular case. : owing to poor road -f&o.flities'. The question of clearance by MT. from these-improvised port's will examined in conjunction with; the aclMinistrative appreciation. ;

10* ; It is' apprcci'4ted that .portswhose breakwaters ebnsist of sunken ships, . and whose piers also- have pierheads, made from vessels beached close .inshore, - are liable to vicissitudes icaused by the vessels moving during galesV The "remedy for-this is to .maintain one or two spare vessels in each port, in precisely the same way as spare blockships are retained at SGAPA FLOW.

11. There is, norother'pbsitipn -in'-'the area which possesses siai r., natural features to that mentioned. above, but it is tho».ght1 -that between BOB® EN BJISSIN raid ®AND0AMP it might be possible to construct a harboixr using a different;. method which is now being developed. ; -1.-• >-•

I x. ;ntorage orts'j- stores ' . •

T', will be observed that if the lighterage ports suggested in paragraph j - ru instructed generally speaking shelter is provided "by "using one -or other of-•eh- . from oil winds ejaolept. Northerly. •

IvL, P

=1(f\\^)rOj31 si

OPERATION 'OVERLORD'

ARROMaNCHES HARBOUR

ANNEXURB to APPENDIX 'X! to GOSSAC(45)28

lv A possible layout of this proposed harbour.is at Sketch ,-£>X' attached; it will be seen that nineteen 400-feet ships will be required to form the breakwaters. The SOUTH breakwater, if re­quired, could be formed either by three additional 400~feet ships or by some form of groyne.

2. It is not known whether the construction of these breakwaters will have any.effect on the depths in the harbour or its approaches, but doubtless expert advice on that point could be obtained*.

3. Ships "A", "BM, "C" and "D" are specially modified 500~.feet piorships which are sunk in positions shown;, each ship.to be capable of b&rthing one ship each ..side* It will be seen that berths "A*- and "B-" are, in the main, deep-water berths, and berths " G'1 and "D" are

' shallow-^water berths. Bach ship would be connected to the. shore by some form of pontoon, equipment in. the'early stages but this would doubtless be replaced by some.form of permanent two-way;pier at a later stage..- - ; -

•%, It .might also be possible to construct some form of quay on the rocks close Westward of • ARROMANCHES, thus providing all-tide ' unloading points for barges, etc#, used by ships secured head and stern to buoys. 1, 2 and 3,

The Eastern end of the harbour could be used to dry out coasters.

6. It is estimated that the daily capacity of this port would be^approximately 6,000 tons.

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