Enigma: the intelligence Linguistics 484. Limits of intelligence In 1798, Nelson simply didn’t know where the French Mediterranean fleet was. Reliant.

Enigma: the intelligenceLinguistics 484

Limits of intelligence

In 1798, Nelson simply didn’t know where the French Mediterranean fleet was.

Reliant on line of sight, flags for ship to ship communication

Navy codebook allowed commanders to say 2000 or so things to each other using flags

Location information was out of date whenever obtained

Crete

Context: Germany preparing invasion of Russia, had invaded Greece more or less accidentally, as result of wish to shore up southern flank.

Opportunity to allow airborne troops to show their skills, since it wasn’t likely they would play a large role in Operation Barbarossa

Crete

Crete

Freyberg: New Zealander, experienced commander, not in the know about where the Ultra intelligence was coming from

The summaryIn addition, 12th Army will allot three Mountain Regiments as instructed. Further elements consisting of motor-cyclists, armoured units, anti-tank units, anti-aircraft units will also be allotted ... Transport aircraft of which a sufficient number, about 600 will be allotted for this operation, will be assembled on aerodromes in the Athens area. The first sortie will probably carry parachute troops only. Further sorties will be concerned with the transport of the air-landing contingent, equipment and supplies, which will probably include aircraft towing gliders ... the invading force will consist of some 30 to 35,000 men, of which some 12000 will be the parachute landing contingent and some 10,000 will be transported by sea. Orders have been issued that Suda Bay is not to be mined, nor will Cretan aerodromes be destroyed, so as not to interfere with the operation intended.

Which units were to land where

Almost certainly in original decrypts

Had Freyberg been able to access these, might have concentrated more force near the airport, which was crucial to resupply of the invading force

Crucial missing information

Limits of intelligence

You have to be able to understand the intelligence.

It is dangerous (but inevitable) to rely on a summary.

If confidentiality means that the summary is made by an off-site intelligence officer then there is a risk that operationally crucial details will not be given and/or asked for.

Battle of the Atlantic

Context

Doenitz -- economic warfare. Experience of almost starving Britain in 1917

1/3 of all food, plus all raw materials except coal and some iron ore needed to come to Britain by sea.

Context

Britain had learned to use convoys in 14-18 war

Escort ships not necessarily of highest quality

Context

Doenitz had two main innovations

use of U-boats to attack from surface using torpedoes. Crucial, because U-boats were relatively fast (17 knots) on surface, so could outrun/keep pace with convoy.

Wolf pack. Spread out to increase chance of contact with convoy, then concentrate

Weaknesses of wolfpack

Needed radio to co-ordinate the members of the pack.

Vulnerable to weather. In bad weather the U-boats needed to stay submerged.

Work on U-boats very unpleasant and dangerous

Shipping lossesYear lost to U-boats

 lost to all enemy causes

1939 50 95

1940 225 511

1941 288 568

1942 452 590

1943 203 266

1944 67 102

1945 30 45

Total 1315 2177

Key statistics

Of 120,000 crew on British merchant ships, around 30,000 died in sinkings of convoy ships (25% loss)

In 43,526 sailings 272 allied ships were sunk (99.4% got through)

Of 40,000 U-boat crew, 28,000 were killed by enemy action

713 submarines were sunk.

Tactics

The main difficulty for U-boats was to locate a convoy at all. 10 U-boats could cover 220 miles of sea.

Role of intelligence

Bletchley Park was frequently able to route convoys around U-boat traps.

German B-dienst was reading convoy signals, and directing U-boats

Signals discipline among U-boat sailors was pretty good, there was a period in 1943 where Bletchley Park was getting almost nothing.

Role of intelligence

British got much better at anti-submarine tactics, using sonar, small aircraft carriers.

John Keegan comments that rivalries and direct appeal to Hitler tended to freeze U-boat tactics at pre-war levels, whereas the Britain, with US help, adapted.

Tactics

Clay Blair points out that evading U-boats is not necessarily the strategically best thing to do.

It might be better to engage them, if you have escorts that are likely to sink them.

Losing a U-boat was worse for the Germans than losing a merchant ship was for the allies.

Keegan’s conclusion

Bletchley’s efforts gave the defenders some advantage, BUT

In the end this was a true battle, with the main factor being the willingness of commanders to put forces into danger and engage with the enemy.

The Battle of the Atlantic could have been won without codebreaking.

Limits of intelligenceAgent Johnson: We believe Burns still has the bill hidden somewhere in his house, but all we've ascertained from satellite photos is that it's not on the roof. The Simpsons, Episode Number: 198    Season Num: 9

Credits

John Keegan: Intelligence in War