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Second
World War British Operations in the Baltic W
J R Naval
Historical Branch Introduction In the latter years of the Second
World War the British secured a very considerable victory over the
last important German naval effort.
This is hardly known about now in even quite enlightened
historical circles. The
reasons for this can be speculated about later.
What is clear, however, is that the potential of an important
series of technological breakthroughs by the Germans in submarine
warfare was not achieved and this was largely, if not entirely, as the
result of well informed and intelligent application of force to the
problem. In particular the
defeat of a new and revolutionary type of submarine was achieved in
large part not by technological wizardry of the same order but by the
humble and often overlooked mine. A
Debate But this was not necessarily
understood by all even then. Two
important voices can be brought to bear against the hypothesis in the
opening paragraph: Grossadmiral Dönitz and Frederick Barley.
The first will be a familiar name but most will not recognise
the second[1].
His worth lies in being one of the authors of the seminal
Admiralty Naval Staff History on the What Dönitz writes is that; ...
success was achieved in keeping the mining carried out by the enemy in
the Baltic to a small degree of significance for the maintenance of
U-boat training, as there were enough available deep water areas in
the eastern Baltic. Only
when the military situation in early 1945 compelled the surrender of
the eastern Baltic and evacuation of the U-boat bases there did the
mine danger increase considerably.
For with growing number of new boats in training at home, the
sea area in the eastern Baltic became without doubt not only in
quantity but also, on account of the lack of depth, in quality a
hampering factor in the training and preparation for operations.
In the last two months of the war therefore ...[3] This statement would appear
uncompromising as a rebuttal of the British Baltic mining campaign
having any significant effect. However,
Dönitz’s claim should be carefully scrutinised. Support for Dönitz appears to come
from Barley:
Fleet and U-boat training, which had taken place in the Baltic
since the beginning of the war, proceeded virtually unhindered until
1941. From 1943 enemy
[British] minelaying precluded exercises in the deep water to the east
of
U-boat training was practically unaffected until 1943.
After that there were some interruptions and losses of U-boats
and U-boat personnel through enemy mines in deep as well as shallow
water. Yet until the
situation in the East deteriorated we were able to maintain the
requisite amount of U-boat training[4]. Barley continues in what appears to
be more nearly his own views:
To sum up, from blockade or ‘bottling up’ mining, few kills
can be expected in the course of a war, and it cannot be relied upon
as a method of appreciably reducing the U-boat menace.
At no time in the 1939-1945 war was the passage of U-boats
seriously affected by this form of mining.
Mining never closed the U/B bases or the Baltic.
Its chief effect was a reduction in the time spent on
operations due to extra precautions and this effect was becoming
progressively smaller as the endurance of U-boats was increased.
This experience of ‘bottling up’ mining is confirmed by
British experience of enemy mining on the East Coast of England in
both World Wars. Few ports
or shipping routes were closed for more than 48 hours even at the
height of the enemy’s minelaying campaign in 1939 to 1941[5]. So where does the balance of truth
lie on this subject - were mines important in limiting the waning but
still considerable power of the German Navy, most especially in the
Baltic? In order to
evaluate the matter it is necessary to start not in the eastern part
of The
German quest for a better submarine In May of 1943, Dönitz and his
groups of submarines - commonly known as wolfpacks - were effectively
defeated by the Allies in the open ocean.
Contrary to some opinions this was not attributable to a single
cause but rather to the cumulative effect of a number of factors such
as escort numbers and proficiency, the use of aircraft, equipment
development and intelligence[7].
What cannot be doubted is that the German U-bootwaffe,
equipped with competent but limited submarines such as the Types VII
and IX were no longer able to operate effectively where they had
before. This is hardly
surprising as these were not markedly better than the submarines which
the First World War had been fought.
Indeed, they were not really submarines at all and had to make
extensive use of the surface to move, find targets then attack them.
These U-boats were probably better considered as submersible
torpedo boats. In the short to middle-term a
series of expedients were adopted.
These included in approximately sequential order: ·
Attempting
to attack convoys on different routes such as the direct
USA-Mediterranean one. This
failed largely because of poor German intelligence and strong escort
forces together with an aggressive ·
A
number of equipment measures including better anti-aircraft armament,
radar detectors and the Schnorkel.
The first two were largely negated by Allied tactics and the
latter improved survivability but severely limited tactical mobility
for the submarine. None of
these, separately or together, resulted in any worthwhile progress
towards regaining supremacy. ·
A
change in mid-1944 to an inshore campaign using single submarines and
virtually no two-way communication.
Although this improved submarine survivability somewhat and
resulted in some Allied loss of shipping it did not produce results on
the scale desired and needed by the Germans.
class=Section8> The Germans were far from
complacent about the situation and this was combined with both a
degree of priority and the technological competence that this nation
has often demonstrated. This
was manifested in the various submarines designed by Professor Walter.
These took a radical approach to propulsion utilising a
hydrogen peroxide propulsion plant capable of delivering high
underwater power. There
were, however, important disadvantages.
Firstly it was very complex and it proved unreliable to the
point where a practical operational submarine could not be produced.
Secondly the fuel was inherently dangerous[8].
The Walter submarine in itself does not directly concern this
account but it does have a part to play in what transpired[9]. What happened was that the Walter
boat proved too radical to promise the prospect of being a practical,
far less a war-winning, weapon, at least in any realistic timescale.
However, the Walter designs comprised far more than just a
high-performance power plant. The
submarines included powerful electric motors, high-capacity batteries
and a hull designed for optimum performance underwater rather than on
the surface. So it was decided to go ahead with
the construction of new submarines which took many of the features of
the Walter boats but not the hydrogen peroxide plant.
These promised nevertheless a huge advance in underwater
performance with the potential to be able to close a convoy, attack
and withdraw, all underwater. Further
an underwater speed either equal to or faster than most escorts
appeared to be practicable. The
designs of these submarines proved to be the basis of submarine
developments in most of the more advanced nations in the postwar years[10]. Radical
Changes to Submarine Production Changes to submarine design were
indeed radical but there were also similar efforts made in the
production of submarines. This
was to some extent because of the effect of bringing Albert Speer, the
Armaments Minister into the system[11].
Not only were many existing working practices considered
inefficient but so too was the whole system of submarine production
which was traditionally based. In
this, sub-contractors produced small components, most of which then
went directly to the shipyard for installation.
In some cases, such as main engines, these would go to the
large component manufacturer, who in turn would send their product on
to the shipyard. It was
there that final assembly would take place (see Figure 1). Under the new system, there was
still a considerable body of sub-contractors but instead of large
component assembly there was a system of assembling sections of the
submarine. There were
eight of these split vertically along the length of the submarine and
much of the sectional assembly was carried out inland.
The completed sections were then moved to shipyards for final
assembly[12]
(Figure 2). There are
several observations worth making at this point.
Firstly, the change in system was not brought about by any
response to any Allied action of which the most obvious one would have
been bombing, especially of industrial targets.
Rather it was because of an attempt to streamline and
accelerate the building of submarines.
Nevertheless it might be argued that the overall system was
probably at least as vulnerable - if only potentially - as the old one
had been. Secondly
although promising efficiency and faster delivery of the new boats
there were sometimes significant difficulties not present in the old
system. One particular one
was that there were very fine tolerances in the dimensions of
different sections so that they could be readily joined to their
neighbours. Lastly there
is the matter of the British observation of empty slipways in early
1944. At the time some
authorities wanted to attribute this to bombing against the building
facilities but it is probable that the transition to the new building
methods is a more likely explanation[13].
The
advent of the Type XXI Whatever the difficulties for the
Germans there is little doubt that they managed to produce a large
number of capable submarines in a relatively short period of time.
It is probable that about 120 Type XXI submarines had been
completed and commissioned by the end of the war in
But between commissioning and
operational service lie a number of barriers.
Any ship or submarine which is a new class, even one less
revolutionary than the Type XXI, needs a series of trials to evaluate
its capabilities and limitations, and to iron out any faults either
endemic to the class or applying to individual hulls.
As well as trials it is necessary to train the crew so that
they can operate the submarine safely and successfully and, finally,
as the potent weapon of war that the submarine should be.
It is very clear that the German Navy understood these
processes well and there is every indication that these were steps
which they never stinted on, even under the pressures of war, and even
when they were clearly losing the war in which they were engaged.
It is difficult to establish the time which the combined trials
and training period ought to take but they were assessed by the
Admiralty in late 1943. There
they gave a figure of “up to six months” for trials and training[15].
If this was a maximum then about four months would seem to be
right for an average submarine. But
this is a figure based on observation of the older Types VII and IX
submarines and on relatively little interference in the activities by
the British. In 1944-1945,
the following factors might be considered to lengthen the process
somewhat: ·
Unfamiliarity
with the new types of submarine (the Learning Factor) ·
Problems
associated with the deteriorating German situation in the war
(Internal Interference) ·
Specific
action by the British to disrupt trials and training (External
Interference) It is obviously difficult to try
and disentangle these factors but some attempts can be made. The
Learning Factor Some 120 Type XXI submarines were
commissioned: only one sailed on an operation before the end of the
war[16].
This was a poor return for the great investment of resources
involved. When it is
considered that the first submarine was commissioned as far back as
June 1944, nearly a year previously, the transformation to operational
service seems inordinately long. The
only submarine to be operationally effective, U-2511, commissioned in
late September 1944, suggested a period of about 7 months in trials
and training. At this
point a total of about 18 other Type XXIs were in commission. What this suggests is that the
minimum number that should have been on operations at this point was
that number. A number of
other figures based on varying training times might be considered to
suggest the number that should have been available without taking
account of the other two factors.
Table
I This suggests two things.
Firstly that the 6-8 month curve is relatively steep and that
the Germans may therefore have been on the verge of actually being
able to deploy quite significant numbers of Type XXI boats.
Had the war lasted perhaps as little as two months longer then
the Type XXI could have been a real rather than an illusory threat.
But this, of course, is counterfactual as is the larger scale
conjecture that a longer European war would have led to the first
deployment of the atomic weapon against The other surmise would be to
attempt to estimate more nearly the number of boats that would have
been deployed without Interference (Internal and External) as defined
above. It is fully
understood that an element of Internal Interference (the deteriorating
German situation in the war) was as a result of Allied action and it
is a very difficult to tease out the contribution made by, say,
bombing of oil-related targets. What
can be said, however, is that if the measure adopted is that of
commissioned submarines then the oil target problem will probably
already have had its main effect in slowing production, transport and
assembly. There remains
the possibility that shortage of oil actually inhibited Type XXI
operations but there is little to suggest that conjecture.
Submarines, in any case, consume relatively little fuel and
there is little on the German naval side to suggest that fuel shortage
was a direct problem for submarine operations[18]. It can be suggested that the order
of Interference effect would probably have denied the Germans between
10 (the 8 month figure) and 30 (a conservative interpolation between
the 7 and 6 month figures) submarines.
If further the Internal/External share is considered to be
equal then the credit due to specific British action is probably in
the order of 10 operational submarines.
Intuitively this is probably kinder to the Internal
Interference cause than it probably deserved.
In any case losing the service of at least 10 of these very
capable submarines is a very worthwhile outcome. The
Baltic Mining Campaign So what form did specific action
take? Essentially there
was only one measure adopted: mining in the Baltic.
Some characteristics of this have to be mentioned at the
outset: firstly the strategic situation caused by the presence of both
nations at the Baltic approaches under German occupation.
This rendered mine laying by surface ships or submarines
impossible and there was only one possibility left - air minelaying.
The second problem concerned the
efficacy of any mining campaign. There
can be few types of warfare in which there are more problems of
determining probability. This
is a constant of warfare. If,
for example, claims made by fighter pilots, anti-aircraft gunners and
submarine captains should always be treated with skepticism and some
form of independent verification.
But these problems are much worse for both mine warfare and
mine countermeasures. From
the miner’s perspective, there are questions, perhaps most marked
when laid by air, of placement and mine reliability.
But the even greater difficulty lies in determining success. How
does a miner know, especially when deploying mines in remote areas
what success has been achieved? A
prudent miner will also assume that the enemy is not sitting still and
will attempt to sweep recently laid mines.
Again on the other side of the coin, in any realistic context
what guarantee has a body in mine clearance have that all mines have
been swept? But probably
the greatest difficulty lies in the matter of knowing what success has
been scored by individual mines. Unlike
“instant” weapons such as bombs, bullets and torpedoes (which have
their own imponderables) a mine may not be actuated for days, weeks or
months, if at all. Even then this makes it very
difficult for a miner to know what fields have been successful, which
have been successfully countered by the enemy and which ought to be
resown. Even in home
waters this can be difficult and the element of the enemy being able
to remove the mines has been removed from this equation.
A good example of this were the antisubmarine mines laid by the
British in the Northwestern Approaches to the United Kingdom in
1944-45 and elsewhere, the success of which was not fully known for
several decades[19]. Considered annually there were
never more than 500 mines laid in the Baltic until after 1943[20].
There were perhaps several limitations which precluded greater
numbers being laid in this period.
These might include: the paucity of suitable aircraft to carry
a sufficient load to the area of the eastern Baltic, typically to the
German exercise areas off the What becomes clear, however, is
that the earlier part of 1944 saw a considerable increase in the
effort applied to mining the Baltic.
The first two months saw very little effort indeed with 25 and
2 mines laid respectively although this slight effort may have been
affected by the weather conditions with ice being at least as much as
a problem for the Germans as it was for the British.
March saw no mines laid at all but April was a different matter
indeed with no less than 861 laid.
There was a further surge in August, September and December
(see Figure 4).
The decision to
intensify the campaign It would be tempting to think that
the April peak in minelaying was a direct response to the advent of
the Type XXI, but the first did not commission until the summer of
that year. However,
knowledge of this submarine did predate the commissioning and it is
possible that any attempt to step up the mining campaign may have been
informed, if not totally, stimulated by such intelligence. One indication comes from a
correspondence beginning on 12 February 1944 and involving the
following: ·
Deputy
Director Operations Division Mining (DDOD(M)), Captain J S Cowie ·
Assistant
Chief of the Naval Staff (UT) (Anti U-boat warfare and Trade
Protection), Rear Admiral J H Edelsten ·
Assistant
Chief of the Naval Staff (Home), Rear Admiral E J P Brind ·
Assistant
Chief of the Air Staff (Operations) (ACAS(Ops), Air Vice Marshal W A
Coryton DDOD(M) then minuted ACNS(UT)
copying it to ACNS(H) noting that there were some 200 U-Boats in the
Baltic and that immediate steps should be taken to disrupt them.
He further noted the development of radar and Pathfinder
techniques which would allow mining carried out from altitude and
through cloud. He
concluded that an intensive British mining campaign would be effective
in countering submarines. Cowie
also used the politically clever point that any such effect would also
bear on the activities of submarines in the period prior to the
invasion of northwest The gist of this was used in a
letter from ACNS(H) to ACAS(Ops) on 17 February adding the further
advocacy of the First Sea Lord to the case[23].
ACAS (Ops) responded on 29 February noting several competing
claims on Bomber Command including reduction of the German Air Force
and support of the Special Operations Executive (SOE) but nevertheless
providing a degree of assurance about Baltic bombing.
He also noted the degree of demotivation in mining aircrew
caused by the non-publication of mining results[24].
It might reasonably be assumed that there were two reasons for
this: ·
The
difficulties alluded to earlier of determining mining results. ·
The
likelihood that the information on minefield success probably came
from Ultra intelligence and although the correspondence in this file
was all “Most Secret”, Ultra was never directly referred to
despite the fact that all officeholders concerned were almost
certainly cleared for access to such material[25]. This last point is almost certainly
alluded to in the last item of correspondence when ACNS(H) assures
ACAS(Ops) of the value of Baltic mining whilst acknowledging that the
sensitivity of intelligence information precluded fuller details being
given[26].
Whether such a piece of appreciation was the most significant
factor in implementing the massive April minelay seems unlikely ever
to be known, but happen it did. Minelaying
Operations In April 1944 the Baltic minelaying
campaign took a huge leap forward with no less than 861 mines being
laid in the Western Baltic[27].
On 9/10 April, for instance 47 Lancaster aircraft of Bomber
Command laid 187 mines of Gydnia and a further 56 laid 120 mines off
Danzig and 164 off Pillau (Baltiysk).
Almost all of these were laid from high-level using H2S
centimetric radar for navigational guidance, a technique that had been
developed recently. By
doing so accuracy was increased, the enemy was less alert and aircraft
casualties reduced[28].
Although this was before the first of the Type XXIs was
commissioned, it is interesting to note the impact of the minelay:
Air
Ministry Intelligence claimed that no less than 40 per cent of German
naval personnel were now employed on minesweeping and escort duties
but that after a heavy [mine]lay the minesweeping forces were unable
to cope expeditiously with the sweeping of the necessary channels.
They claimed that after this operation
Captured German Naval records show that this mining operation
undoubtedly caused considerable disruption in the A similar, if reduced, scale of
minelaying was seen in August, September and December with 463, 216
and 264 mines respectively[30].
Again results were significant. At
the end of August, for example, when 171 mines were laid in When
therefore the presence of hostile aircraft was noted over the
Sweeping located only a few mines and it was assumed that a new
variety of firing assembly had been incorporated.
This necessitated meticulous sweeping with strict convoying and
meant unavoidable delay in re-opening any of the U-boat training
areas. To anticipate the
narrative, on 6 September Admiral von Friedeburg, who was responsible
for all U-boat trials and training, reported that the mine situation
in the gulf of Danzig was preventing him from carrying out trial
schedules, particularly those concerned with the new Types XXI and
XXIII. He urgently
requested the clearance of at least the U-boat Acceptance area which
lay close off Hela as well as provision for adequate mine escort for
U-boats proceeding via the compulsory routes to this area.
The only outcome was that on 8 September a part of the deep
water technical training area was re-opened but with the restriction
that U-boats must keep at least 50 metres (162 feet) of water under
the keel.
More hostile aircraft were detected over the Gulf on the night
of 15/16 September [75 mines laid] and no other parts of the training
area were re-opened until: 20
September
-
The Acceptance area off Hela 24
September -
Part of the general torpedo firing area but restricted to
keeping more than 50 metres under the keel 1
October -
Part of the C.O’s torpedo firing are but restricted to a
diving depth of 35 metres (114 ft.)[31] What this demonstrates is the
effect that mining had on the process of bringing submarines up to
frontline service, an effect that was worthwhile, economical and -
considered cumulatively - reasonably long-lasting.
The
Application of Intelligence What has been clearly established
now is that mining of the Baltic submarine trials and training areas
was both economical and effective.
A further point was the large amount of force tied up by the
Germans in countering this relatively small-scale effort[32].
Beyond that there were some losses to German shipping: surface
warships (including minecountermeasures vessels), merchant ships and
even the occasional submarine. But
the main importance remained the large-scale disruption to the German
advanced submarine operational programme.
What has not been quite so evident is the role of intelligence. There have been several hints
dropped outside of the main documentary evidence of the relationship
between intelligence and Baltic minelaying, most especially by Patrick
Beesly[33].
However, the main evidence must be found in the papers of the
Naval Intelligence Division itself.
This largely falls into two
categories: evidence of knowledge of the German view of the Baltic and
mining, and a late monograph on the subject.
The former, it is clear, is not just confined to one period of
time but rather indicates a thorough knowledge of German trials and
training areas, and German perceptions of minefree routes[34].
It includes, for example: ·
Index
of Reference Points and Swept Ways ·
Baltic
Swept Ways ·
Exercise
Areas in the ·
Changes
in U-boat exercising areas in the Baltic ·
U-Boats
in the ·
Fleet
Anchorages
There are some uncertainties
expressed, generally positional as “possibles and “probables”
but the general impression is of very comprehensive knowledge and no
suggestion that the Germans suspected that the British knew as much as
they did. The monograph does not make its
provenance totally clear. However
it is written on Operational Intelligence Centre form paper indicating
two important things: ·
That
it is unlikely to have been written later than the end of 1945 as the
OIC was abolished at the end of the war ·
It
was probably written by someone who was a practitioner of the art of
operational intelligence described in it.
It is a large document
notwithstanding the use of double-spaced typing - 21 pages of large
format paper and a few points made in it are described below[35]. It mentions, for example, the
deliberate tactic of simultaneously mining two well-separated points
in order to place the maximum possible strain on the minesweeping
forces[36].
It was noted that these and other minelays had a marked
demoralising effect on the Germans[37].
But the implications of these operations were not just
irritating and bad for the German psyche.
They had material effects other than the ones noted earlier in
this paper. An
illustrative instance of this occurred in March 1945 when British
action resulted in lack of minefield escorts for “main units
[submarines, large transports and other warships]” operating in The production of intelligence is
dealt with to some extent, too. It
is made clear, that this very useful product was the result of many
sources of intelligence, a skill which the Operational Intelligence
Centre had to a large extent perfected during the course of the war.
Captured documents were of use, as was photo-reconnaissance and
observations from adjoining countries.
The British Naval Attache in neutral Sweden, for example, was
able to interview masters of neutral merchant ships involved in
supplying U-boats and although the latter went to some lengths not to
display their identities by submarine number, they had used them when
signing for repairs and bunkering.
The amount of fuel taken on in the latter operation often
indicated the difference between a boat continuing in training or
about to start an operation[39].
But what the monograph also indicates is the importance of
“Special” or what has become known as Ultra. A clear list is given of items
which Ultra gives the only reliable indication.
These include: ·
Casualty
details ·
Effects
on routes and harbours - resultant disorganisation ·
Sweeping
difficulties ·
Accurate
convoy routes and deviations therefrom[40] class=Section21> | ||||||||||||||||||
