Extracts of Anti-Submarine Warfare Reports, November-December 1939.
The U-boat Offensive
(a) The underlying motives
motive behind the U-boat campaign in November seems to have been an
attempt to prove to neutral countries that it was suicidally dangerous
to trade with Britain. By the beginning of November the Germans showed
by their conduct that they had abandoned all pretence of observing those
rules of international law that relate to sea warfare. Neutral ships as
well as British were torpedoed without warning, and the fairways along
which merchant ships must pass were strewn with mines; The Germans first
denied that this was true and then they made an attempt to justify their
acts, but since their case was bad they tried to confuse the issue with
Thus an article appeared in the Börsen Zeitung,
saying, "There is one principle of international law on which
Germany is in full agreement with England, that is, the principle of
‘continuous voyage.’ Germany has the right to stop and seize goods
destined for England which are first shipped to a neutral country."
Other articles maintained that papers of ships were falsified to give
the impression that goods actually being shipped to England were going
to a neutral destination.
States," wrote the Deutsche Allgemeine Zeitung, "are
not likely to approve this device, and Germany is bound to reply by
tightening up her control to the inconvenience of neutral shipping."
The German "control" could only be exerted by submarines and
minefields and their method of "tightening up" was to neglect
the laws of common humanity.
Yet the German press at the same time praised the chivalry
of their submarine officers. One German newspaper gave an account of a
submarine that torpedoed a British fishing boat. Six of the crew were
drowned, but the others were given clothes, food and brandy aboard the
submarine and transferred to another trawler with the message,
"Tell Mr. Churchill
German submarine crews are not heartless murderers." (The
story probably refers to the sinking of the "Cresswell.") The
writer of the article seemed to be genuinely unaware that it was an odd
message to entrust to men who had just seen half of the crew of their
ship either killed or die from exhaustion.
the month of November the main effort of the German High Command seems
to have been centred upon a mine-laying campaign on the East Coast,
particularly in the Thames estuary. It is impossible, however, to be
certain that ships reported as having been mined were, in fact, not sunk
by torpedoes, or to establish whether the mines themselves were laid by
aircraft, surface ships or submarines, but there are indications that
U-boats laid lines of mines across the fairways off the East Coast.
the Western Approaches it appears that an average of only two or three
U-boats were operating during the month. This small number may have been
due to a temporary shortage having been produced by the destruction of a
considerable proportion of the German ocean-going U-boats.
On our western and southern coasts there was some activity
off the entrances to harbours. It seems possible that here also the
enemy were laying mines or trying to emulate what Kapitän-leutnant
did at Scapa Flow
, for on one
occasion our motor anti-submarine boats attacked two contacts in the
Firth of Clyde
and another U-boat was detected attempting to penetrate deep
into the Bristol Channel.
were also apparently two U-boats on patrol between the Bay of Biscay and
the Straits of Gibraltar
at the beginning of the month. Four neutral ships were stopped
and their papers were examined. One of the U-boats responsible was
described as displaying the skull-and-crossbones on its conning tower.
It is possible that the French destroyer "Siroco"
accounted for both these boats.
the end of the month, when the German High Command realised that the
presence of the "Deutschland" would probably bring our heavy
ships into the Northern Approaches, a patrol line of U-boats seems to
have been placed between the Shetlands and the Norwegian coast. It was
one of these U-boats which unsuccessfully attacked H.M.S.
on the 28th November, and another- "U.35"-was
destroyed by the "Kingston" and "Kashmir" on the
reports of U-boat activities much farther afield, in the Canaries and in
the West Indies, are being continually received. Since no attacks have
taken place south of the Straits of Gibraltar, these reports are in all
There is evidence
that the Germans use the Fair Island Channel
when outward bound; the interrogation of survivors of
"U.35" tends to confirm this.
is very difficult to make any estimate of the total number of U-boats
sunk, but it is noteworthy that two of the survivors of "U.35"
stated that, in their opinion, the U-boats could not be considered as a
U-boats are no longer divided into flotillas, but grouped as the
strategical situation demands.
(c) U-boat tactics
officers of "U.35" all said that it was found necessary to
dive continually in order to avoid being sighted and reported by
aircraft. They also said that aircraft made it impossible to send a
prize crew on board a neutral vessel and to obtain fresh provisions,
unless they went alongside the ship or compelled the crew to bring
supplies in their own boat. They added that they did not fear bombing
from aircraft very much, as it was usually possible to dive to a safe
depth before the aeroplanes could attack. They thought there is always a
danger, however, in low visibility, and more especially when the sky is
half covered with clouds, as it is then that aeroplanes may surprise
have standing instructions to dive on sighting aircraft, as firing
recognition signals takes far too long. Six men are apparently kept on
the bridge as aircraft look-outs. The Captain of "U.35" said
he thought that, if they were sighted by a merchant vessel, aircraft
would probably be on the spot in twenty minutes.
submarine sighted by a U-boat while in her operational area is not
attacked, unless she is definitely proved by her silhouette to be
attacked, U-boats go to 70 metres (230 feet) if it is not possible to
bottom. It is noteworthy that depth charges which exploded below
"U.35" were much more feared than those which exploded above.
The Germans know, however, that our depth charges can be set to 500 feet,
which is greater than any depth to which their U-boats can go.
Captain of "U.35" stated that he had learnt to distinguish
between destroyers sweeping with asdics and destroyers in contact. In
his experience the destroyers usually lost contact after firing depth
charges. He said he would have been unable to attack the destroyers
which hunted him because they always remained bows on.
officer also stated that if a single British destroyer were picking up
the survivors of a U-boat she had sunk, a second U-boat in the vicinity
would probably not attack the destroyer, if it was obvious that rescue
work was going on; but, if the second U-boat could not see why the
destroyer had stopped, because of the range or the visibility, an
attempt to torpedo the destroyer would certainly be made. He added that
his advice to an unaccompanied destroyer in these circumstances would be
to steam round two or three times to make sure that there was not a
second U-boat about and only then to stop and pick up the survivors of
the first U-boat (The Admiralty has definite indications that two
U-boats are unlikely to be so close that such an attack is possible.)
(d) The first cruise of the
account of the first cruise of the "U.35" has been pieced
together by facts obtained from the survivors of the U-boat which have
mostly been corroborated by other evidence, but it is possible that it
contains errors. It is included as being typical of a cruise of a German
U-boat operating in the Western Approaches.
left Wilhelmshaven after dark on Friday, 8th September, apparently with
orders to pass through the Dover Straits, if it was thought feasible. At
dusk the following evening the “U.35” was attacked in the vicinity
of Borkum by a British S/M (Note- H.M.S. “Ursula” reported she had
attacked a U-Boat on 9th September with torpedoes from 3,000 yards). The
splash on discharge of torpedoes was seen. “U.35” stated that three
torpedoes were fired at her, and as she sighted their tracks she was
able to comb them. The captain of “U.35” said that he then turned
towards the S/M and attempted to ram her at a speed of about 12 knots.
The estimate he gave of the range on firing was about 500 metres (547
“U.35” then apparently turned to the northward and on
the following day— 10th September—she was attacked by a large
aeroplane which dropped three bombs. (The Air Ministry have a report of
an attack on a U-Boat at 180 miles east of Aberdeen on this day, which
was considered unsuccessful.) The bombs were close enough to break
several electric light bulbs but no other damage was done. After this
incident “U.35” kept an especially sharp look-out for aircraft, and
the Petty Officer Telegraphist (Funkmaat) used to listen for wireless
transmissions from our machines and could very often pick them up and
say whether they were approaching or going away.
The passage through the North Sea was slow as “U.35”
remained submerged during daylight hours. She passed through the Fair
Island Channel—probably during the night of 16th or 17th September. (This
statement is possibly intentionally misleading.) At about 17.30 on
Monday, 18th September, “U.35” sank the trawlers “Lord Minto” and “Arlita” by gunfire in a position 57° 51’ N., 9° 28’ W. (N.N.W.
of St. Kilda). The survivors were put on board the trawler “Nancy Haig,”
and the Captain of the “U.35” told the skippers that he
made it a rule to sink two ships and let one go free. During the whole
cruise the Captain of the “U.35” appears to have behaved in a humane
manner and to have treated the crews of the ships he sank with
Later on the same day, at 13.30 “U.35” sighted the
fishing trawler “Alvis” and stopped her with gunfire. The skipper of the trawler came
over in a boat to the U-Boat and was well received. A German officer and
three men were sent to the “Alvis”; the wireless fittings were
dismantled and the fishing gear destroyed. The Captain of the U-Boat
then gave the skipper of the trawler a bottle of gin, after which the
crew were told to return to the trawler and go back to Fleetwood.
In contrast to her slow passage hitherto, “U.35” now
proceeded rapidly to the Western Approaches, and by 14.20 on 21st
September, she was able to attack a convoy in a position 490 29’ N.,
60 50’ W. She fired two torpedoes, the first missed the S.S. “Inanda,” (one of the leading ships) and the second hit the S.S.
“Teakwood” (in the rear of the convoy). This vessel was not sunk and
managed to reach harbour. The counter-attack by the destroyer escorting
the convoy was not delivered for another two hours. According to the
report of the Captain of the destroyer, contact was doubtful and there
was little hydrophone effect; consequently there was only one depth
charge dropped, but this was so accurately placed that one periscope was
rendered useless and the other was slightly damaged, and “U.35’s”
high-pressure blowing system was temporarily put out of action.
“U.35” then involuntarily bottomed in a depth of 67 fathoms, where
the flooding valves to the main line began to leak. Repairs were carried
out while bottomed, and the Engineer Officer later received the Iron
Cross, 2nd Class, for his work.
After this episode “U.35” passed right into the English
Channel and the crew reported sighting Beachy Head and cruising off Le
Havre and Cherbourg. They also claim to have been in a position to
torpedo the “Acquitania”
(which was unescorted) at 400 metres range, but refrained from
doing so, because “it was against orders to attack passenger ships.”
“U.35” did not attack any shipping while in the English Channel and
by 1st October was cruising on a line between the Ushant and Land’s
End. On that day she stopped the Belgian S.S. “Suzon” with gunfire,
and, when the crew had abandoned the ship, she was torpedoed.
At about 13.00 on Tuesday, 3rd October, the Greek S.S.
“Diamantis” was sighted in a position 49° 22’ N., 6° 46’ W. The
weather conditions were very bad and the sea very rough, and the signals
made by the “U.35” to the Greek were apparently not read. “U.35”
then fired a round which fell ahead of the steamer. The U-Boat’s
Captain and Officers said there was no intention of sinking this ship,
as the sea was considered too rough for the “Diamantis’” boats.
The Greeks became panic-stricken however, and got into the boat and cut
the falls. The boat capsized on reaching the water, and “U.35” had
great difficulty in rescuing the crew. They were very well treated on
board and the shortage of provisions that “U.35” experienced at the
end of the cruise is partly attributable to the large appetites of the
Greeks. While the “U.35” was taking the crew on board they were
surprised by a flying boat, which machine-gunned them as they were about
Owing to the heavy seas running, the first two torpedoes
fired at the “Diamantis” missed, and a third torpedo was needed.
“U.35” then proceeded submerged until about 18.00 when
she surfaced. At about 16.30 on the following day, 4th October,
“U.35” arrived in Dingle
Bay. She came to within about 25 metres (27 yards) of the
shore and landed the Greeks, four at a time, in a collapsible boat. This
took about twenty-five minutes; the Captain of “ U.35” said that he
was nervous the whole time, as he feared aircraft might sight them at
“U.35” had now been at sea about four weeks, and the
Captain decided to return home. The only incident experienced on the
return passage was hearing a number of explosions. These were taken to
be depth charges and as many as 67 were counted. They may have heard,
however, the attack by German aircraft on the 2nd Cruiser Squadron on
Bad weather was experienced during the whole of the
homeward journey. They apparently arrived in harbour with only one
hour’s fuel on board. The Chief Mechanician said that he thought that
they had not been economical with the oil and he thought that a U-Boat
could reasonably be expected to remain at sea for five weeks without
re-fuelling; the Captain, however, said that he thought five weeks was
too long a cruise because of the strain that it imposed upon the crew.
On return to harbour “U.35” proceeded up to Hamburg for
her annual re-fit in the yards of Blohm and Voss, where she stayed for
about four weeks. During this period the crew were given fourteen days’
“U.35” proceeded on her last cruise on the evening of
19th November, and was sunk on 27th November by H.M. destroyers
“Kashmir” (Commander H. A. King) and “Kingston” (Lieutenant-Commander
P. Somerville). As no report has been received in the Admiralty, the
account of the destruction of “U.35” is held over.
Narratives of Encounters with
Last Cruise of the U.35
“U.35” sailed from Wilhelmshaven on the 18th November.
It seems that the Captain’s original orders were to proceed to an
operational area in the Western Approaches,
but a few days after leaving he received fresh instructions, probably
because of the presence of the “Deutschland” in Northern Waters.
Apparently “U.35” was one of three U-Boats forming a
line stretching from the Shetlands to Norway. The weather was
continuously bad. “London” class cruiser, probably H.M.S.
but “U.35” was unable to attack because of the sea that was running.
“U.35” was harassed by aircraft and was sighted once when she was on
the surface in the neighbourhood of the Orkneys. From the notebook of
one of the stokers which contained readings of the battery, it seems to
indicate that she dived during most of the night. It is extremely
unlikely that a U-Boat would be dived during dark hours unless she was
carrying out a specific operation. It therefore seems possible that
“U.35” attempted to enter one of the Northern Harbours, probably
Scapa Flow or Sullom Voe on the 29th November, when she was sighted by
one of our destroyers silhouetted against the rising sun.
At 10.37 Rear Admiral (D) commanding the Home Fleet
destroyers instructed H.M.S. “Kashmir” (Commander H. R. King), with
H.M.S. “Kingston” (Lieut.- Commander P. Sommerville), in Company, to
close H.M.S. “Icarus” (Lieut.- Commander A. J. Maud), who had been
attacking a submarine. H.M.S. “Icarus” gave the range and bearing of
the submarine and then H.M.S. “Kingston” and H.M.S. “Kashmir”
started a search. About 2 miles before the estimated position of the
submarine H.M.S. “Kingston” obtained contact and attacked, dropping
three depth charges, with no visible result. This attack, in point of
fact, damaged the hydroplanes and put the wireless gear out of action
and broke the glasses of one of the periscopes.
H.M.S. “Kashmir” then had considerable difficulty in
maintaining contact, apparently because of the eddies the depth charges
set up. H.M.S. “Kashmir” was running in on her attacking course when
H.M.S. “Kingston’s” second pattern of depth charges exploded some
400 yards ahead and the U-Boat was seen to surface. The oil tanks and at
least one ballast tank had been badly damaged by H.M.S.
“Kingston’s” attack, and the submarine had to surface as the after
hydroplane jammed at hard arise.
The crew came up on deck and some of them started to man the gun. H.M.S. “Kashmir” fired a shot across her bows and they left the gun, held up their hands, and started to abandon ship. About the same time the submarine’s way stopped. H.M.S. “Kashmir” approached from aft and picked up four officers and 27 ratings. H.M.S. “Kingston” carried out a circular sweep. When this was completed H.M.S. “Kingston” closed. Immediately after surfacing the U-Boat began to sink and by the time H.M.S. “Kashmir” was lying off only the conning tower and the upper side of the forecasing were visible. “U.35” finally disappeared by the stern 20 minutes after she first appeared, in a depth of over 120 fathoms.
Miscellaneous information about German U-boats
(This information was obtained from interrogation of prisoners of war)
The Captain of the "U.35" was highly satisfied with German torpedoes.
The following facts were also obtained:-
(1) Note. - It is known that the Germans have electric torpedoes.
(b) German A/S device
The Germans are known to use some crude form of Asdic known as Periphon. These are stated to be not nearly as good as our Asdics. There are shore control hydrophones East of declared German minefield. Submarines are fitted with revolving hydrophones similar to our RDH installation in use about 10 years ago. These give an indication of the movements of ships, and it is possible to estimate their speed and tell whether the vessel is large or small. The Chief Hydrophone operator of "U.35" stated, however, that they never counted ships' revolutions. He also said that he thought our Asdic was a variation of a wireless beam which when sent out required some noise in the submarine to modify it and render it audible in the receiver.
(c) German Mines
It was stated that minelaying was done principally by the 250-ton boats and that they only carry six mines (it is known that they can carry 12, but this greatly reduces the habitability of the boat). The torpedo tube contains two mines, and these are pushed out of the tube together by compressed air acting on a plate which seats behind the rear mine. It was freely acknowledged that the mines were magnetic - but nothing was apparently known about acoustic mines. The mines themselves are said to be the outcome of many years research but the explosive, though very powerful, is rather unstable.
The morale of the crew of "U.35" appeared to be very high and their will to victory (das Willen zum Sieg) is most pronounced. There is apparently competition to join sea-going U-boats. Most of the crew took part in the first cruise of the "U.35" and seem to have enjoyed it.
The Depôts are said to contain numerous spare crews. These receive three months' training on shore and are then drafted to sea-going U-boats for one cruise, supernumerary of complement. Thus "U.35" had 43 men on board instead of the usual 36. This reduced the number of torpedoes she could carry. The crew was exercised in working in the dark, so that if a depth charge put out all the lighting, they can still carry on with their jobs. Two of the crew stated that, after being very badly shaken up by the depth charges when they sank the tanker "Teakwood" in convoy, they had no wish to attack another convoy. When the Captain stated that he was going to do so, they said that everyone showed signs of nervousness, such as pulling their ears or scratching their noses.
The crew of "U.35" stated that they were very well treated in H.M.S. "Kingston" and "Kashmir." This made them very much more easy to interrogate afterwards. (It is thought very undesirable to attempt any detailed interrogation at local ports and it is essential that all notebooks, papers, etc., should be forwarded to the Admiralty forthwith.)
(e) German communications
"U.35" sent out only one signal during her two cruises. The wireless operator said that the Germans could get accurate D/F fixes of high frequencies, and they knew that our D/F organization also was extremely good. There are two wireless sets fitted in submarines, one high frequency with a range of 3,000 to 20,000 k/cs. On the other a medium frequency set with a low limit of 300 k/cs.
The U-boats keep an irregular receiving watch on the commercial frequency (500 k/cs.).
Under-water communication is carried out with a beam which is received in the hydrophones. The beam has a dispersion of 10° and a range of three kilometers (2 miles) - the sounds are just within the limit of audible frequency. Code is used for these transmissions.