Transcript Limits

Enigma: the intelligence
Linguistics 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Location information was out of date whenever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 summary
In 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.
Crucial missing
information
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
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 losses
Year
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
intelligence
Agent 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