Extracts of Anti-Submarine Warfare Reports, November-December 1939.

November 1939:


   The U-boat Offensive 

(a)  The underlying motives

The 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 irrelevant arguments.

 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.


"Neutral 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.


(b) U-boat activities

Throughout 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.

In 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 Prien  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.


There 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.


At 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. "Norfolk"  on the 28th November, and another- "U.35"-was destroyed by the "Kingston" and "Kashmir" on the following day.

Further 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 probability false.

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.

It 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 decisive weapon.

German U-boats are no longer divided into flotillas, but grouped as the strategical situation demands. 


(c)  U-boat tactics

The 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 them.

U-boats 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.

A submarine sighted by a U-boat while in her operational area is not attacked, unless she is definitely proved by her silhouette to be hostile.

When 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.

The 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.

This 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 "U.35"

This 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.


"U.35" 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 yards).

 “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 consideration.

 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 to dive.

 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 any moment.

 “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 9th October.

 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’ leave.

 “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.  

December 1939:


 Narratives of Encounters with U-Boats  

i) 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. “Norfolk,”  was sighted 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)

(a) Torpedoes

The Captain of the "U.35" was highly satisfied with German torpedoes.

The following facts were also obtained:-

(1) The pistols are extremely sensitive. The torpedo officer stated that torpedoes had on occasion jumped out of the water and detonated on re-entry. This he said was due to the over-sensitivity of the contact device and was not caused by magnetic firing.

(2) Air pressure in German torpedoes is 200 atmospheres (3,000 lb/square inch). Torpedoes are struck down into the U-boats charged with air, but have to be "topped up" from time to time.

(3) U-boat torpedo tubes are fitted with external angling gear which is adjustable to every degree. In practice only 10° adjustments are ever used. Even this accuracy of angling the gyro is thought to be unnecessary.

(4) U-boat torpedo tubes have external speed-setting gear. The settings are sometimes altered during an attack.

(5) Officers of the "U.35" stated that they thought the electric torpedoes were a fancy of scientists.(1) "U.35" certainly used air torpedoes.

(6) It was claimed that the German explosive is of higher density than the English.

(7) Torpedoes are set to hit, not run under.

(8) Many comments were made on the great difficulty of embarking more than three torpedoes in a 250-ton submarine.

(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.

(d) Personnel

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.