To anyone interested in the topic, a healthy re-appraisal of the influence
https://www.usnwc.edu/getattachment/1f40e9ba-42c9-4861-bc7e-c2554ec2909b/The-Other-Ultra--Signal-Intelligence-and-the-Battl.aspx
Although the British had the edge in that department, the intelligence
contest was far from completely lopsided against the Axis, and ULTRA was
not a decisive asset in naval warfare.
What is the definition of decisive?
It seems another round of Ultra the decisive versus Ultra the insignificant,
in this case it is nice to see a case study with examples. It has been made
clear Ultra was an opaque view of the axis, lack of context, incorrect
information (Rommel's supply people seemed to have trouble counting
the supplies they had and the supplies they used, signaling they were
having shortages), changes of plan, missed or partial messages and so
on. In the Mediterranean the British used Ultra to build up a profile of
the axis merchant fleet, what cargo individual ships had carried, where
they had sailed to and so forth, to enable prediction of convoys and
cargo. The spur for this was apparently the fact a German ship made
it into Benghazi as Rommel was retreating in January 1942, despite
all the predictions the port was blocked or if not blocked could not
unload cargo.
The British rated the Italians as harder to fool than the Germans.
The Italian SIS certainly understood the benefits of fast work, it
is interesting to note in the examples given much of the necessary
information for the Italians could be gained from traffic analysis,
with the decryption a bonus. The lack of radar on board Italian
ships is highlighted by the need for SIS to warn the ships about
allied aircraft.
Admiral Cunningham noted to their credit the way the axis merchant
ship crews and convoy escort ships kept trying to supply Africa to
the end despite all the losses.
The review is using the Italian official figures for cargo shipments, the
17 months where the losses were 10% or less were June to November
1940, January to June 1941, January, February, April, May and July
1942. There was zero cargo loss to end November 1940, then 10.65%
in December.
The table is Luftwaffe sorties against Malta, % shipping losses, 1941
Jan / 451 / 2.81%
Feb / 387 / 1.46%
Mar / 511 / 8.89%
Apr / 637 / 8.04%
May / 755 / 8.01%
Minimal Luftwaffe activity over Malta for the rest of the year, cargo
losses were June 6.19%, July 19.13%, August 12.56%, September
28.27%, October 20.37%, November 62.32%, December 18.01%
Force K, the Malta based cruiser strike force, was created in
October 1941.
U-boats became active in the Mediterranean in late 1941, Ark Royal
and Barham were sunk in November.
On 19 December Force K was effectively destroyed after running
into a minefield, while Queen Elizabeth and Valiant were crippled
at Alexandria.
1942, Luftwaffe sorties versus Malta, axis cargo losses.
Jan / 1468 / 0.07%
Feb / 1935 / 0.85%
Mar / 4300 / 17.3%
Apr / 8788 / 0.78%
In late April and early May the 5 remaining submarines based at
Malta leave for Alexandria, 4 make it.
May / 2476 / 7.24%
Jun / 956 / 22.14%
Jul / 1819 / 6.45%
In late July and early August 4 RN submarines return to Malta,
soon joined by more.
Aug / 862 / 33.03%
In late August 217 squadron, Beaufort torpedo bombers, is
released to continue onto India, after 2 months at Malta 8 out
of the original 19 crews remain. The Beaufort strike force is
built up to 22 crews with 20 aircraft, number 86 and part of
number 39 squadrons.
Sep / 391 / 20%
Oct / 2842 / 44.2%
Nov / 105 / 25.85% (To Libya, cargo to Tunisia had no losses)
There is a nice but imperfect correlation between axis effort
against Malta and cargo losses. July is almost an anomaly
in terms of cargo losses, given the upswing that started in May.
By mid 1942 the fuel situation at Malta was so bad air tests
of repaired aircraft had been stopped, crews found out if
the aircraft had been properly fixed on its next combat
mission. Submarines were being used to ferry in supplies,
reducing the number available for offensive patrols. The
arrival of the Ohio in mid August was a major turning point.
About 9 torpedo aircraft was a maximum effort strike from
Malta in mid 1942, and it was not until around August the
strikes could be co-ordinated with Beaufighters who
would do escort and flak protection, enabling daylight
strikes with lower losses.
In addition to the Malta supply effort the Alexandria based
submarines were more concentrated on interdicting the
axis supply lines to the Greek and Italian islands in the
eastern Mediterranean, which did include the convoy
routes to Africa from Greece and Crete.
In September 1939 the RN had 56 submarines, of these 12
had been laid down between 1917 and 1919, the rest from
1924 onwards as part of a steady building program, there
were 41 RN submarines in January 1935.
By January 1942 the total had risen to 60, including 10 of
the WWI boats, plus 2 WWI boats from the USN, despite 37
losses, the number available was 72 by end August (including
the 10 RN WWI and 6 USN WWI boats) and 83 by end
December (17 dating from WWI), plus some submarines
from the Dutch Navy, 19 RN submarines were lost in 1942.
Note these figures include any under repair or refit.
Given the Doenitz rules of a third on patrol that equates to
around 24 on patrol from Norway to Alexandria, in August
1942, up from 20 in January, since few were retained in the
Indian Ocean. Then deduct the number used for training,
including for anti submarine forces.
Rommel started his 1942 offensive on 26 May, Tobruk fell
on 20 June, the first German units arrived at Alamein on
1 July, fighting occurred around the Alamein position for the
next month, then a lull for a month, then on 30 August
Rommel launched a major attack, which was called off on
2 September. It is clear the sinking of ships had nothing to
do with the attack being ended, though the general supply
situation did not help, but the sinkings gave a convenient
excuse given the supply requirements sent pre battle.
By October axis dispositions had been influenced by the
fuel situation, and it was understood that any lateral move
along the line was close to one way, the available fuel did
not allow forces to shuttle back an forth.
The first two convoys the paper discusses give an idea of
the amount of time available to intercept and the defences,
1) Left Taranto 13:00 on 2 July, arrived Benghazi 18:45 on
4 July, 3 merchant ships and 8 escorts.
2) Left Crete 21:40 on 8 July, arrived Tobruk 13:50 on
10 July, 6 merchant ships and 6 escorts.
In addition the short routes gave greater chances to salvage
damaged ships.
July 1942 marked a low point in British ability to interdict
axis supply convoys to North Africa, given the situation at
Malta and at Alamein. This can be seen by the size of the
strike forces, the number of convoys that were not attacked
and the composition of the strike forces, including the
anti submarine Hudsons and heavy bombers, though the
range of the latter comes into play given where allied
airfields were in August 1942.
The withdrawal of the Albacores from Malta indicates the
problems of operating with long supply lines. The RN had
many problems in trying to keep its aircraft units up to full
strength.
The fact much Ultra information came from the Luftwaffe
organising fighter and anti submarine escorts shows the
complexities, the convoys were easier to find but harder
to attack in daylight, hence the number of night attacks.
R V Jones makes the point the British had a good idea
of the German forces invading Greece in 1941, but lacked
the forces needed to stop them. The quote I have seen
about Ultra and the Mediterranean shipping war is that
Ultra was a force multiplier, enabling much better
outcomes for the forces deployed. Essentially Ultra
can be measured by looking at the number of successful
interceptions versus the allied forces deployed, after that
it is the combat units that need to score the hits. The
losses the British forces were taking reduced the overall
effectiveness of the forces, training had to be cut to fill
losses, many attacks failed due to inexperience. There
was essentially no opportunity to train for the Malta
based units. Ships were also harder to sink than the air
forces generally believed.
The review really could do with a look at the number
of forces actually available to intercept the convoys,
given as of July 1942 the Axis had 3 African ports.
The higher the number of successful searches per
aircraft sortie or attacks per submarine patrol the
more likely Ultra is helping the allies.
While the British understood the importance of fuel and
prioritised tankers it is interesting to note to the end of
January 1943 while 14% of all axis cargo shipped to
Africa had not arrived the losses were, 11.5% of vehicles,
11.7% of "other supplies", 12.1% of ammunition and
stores and 20.5% of fuel, Ultra would take credit for some
of the extra fuel losses. Also note 13.2% of the cargo
landed in Africa to end January 1943 was for civilians.
To complete the axis cargo loss figures, November 1942
to May 1943, monthly shipments to Libya and Tunisia,
18.5%, 31.7%, then in 1943, 21.3%, 22.8%, 35.7%
41.2% and 76.7%.
To the end of July 1942 the Germans in the Mediterranean
had lost 9 merchant ships to surface warships, 17 to
submarines, 10 to aircraft, 10 to mines and 6 to other
causes, total 52, in the final 5 months of 1942 another 24
were lost, 1 to surface warships, 9 to submarines, 5 to
aircraft, 3 to mines and 6 to other causes.
The Italian figures I have include losses outside the
Mediterranean, to end July 1942 losses were 27 to surface
ships, 134 to submarines, 86 to aircraft, 43 to mines and
34 to other causes, total 428, in the final 5 months of 1942
losses totaled 150, 5 to surface ships, 47 to submarines,
58 to aircraft, 6 to mines and 34 to other causes.
On another note expressed as a percentage of the tonnage
of ships entering or leaving Britain on foreign trade voyages,
which includes ships with cargo or in ballast, the world wide
axis anti merchant ship operations sank,
5% in 1940, 8% in 1941, 16% in 1942, 5% in 1943 and 1% in
1944.
It does make the loss figures look better given ships did
several voyages a year. Think of what it would look like as
a percentage of cargo ship tonnage entering and leaving US
ports.
Geoffrey Sinclair
Remove the nb for email.