This record was kindly provided by the generous assistance of Roger Griffiths

	COPY No.
	This book is invariably to be kept locked up when not in use and is not to be taken outside the ship or establishment for which it it issued without the express permission of the Commanding Officer
	C.B.  04051 (93)
	"U 536"
	Interrogation of Survivors
	January, 1944
	This Report is not to be considered accurate in all respects, having been prepared before complete information was available.  It is therefore not to be taken as historically correct.

 

	SECRET
	This book is the property of His Majesty's Government.
	It is intended for the use of the recipients only, and for communication to such Officers under them (not below the rank of Commissioned Officer) who may require to be acquainted with its contents in the course of their duties.  The Officers exercising this power will be held responsible that such information is imparted with due care and caution.

 

 

	SECRET
	Attention is called to the penalties attaching to any infraction of the
	Official Secrets Acts.
	C.B.  04051 (93)
	"U 536"
	Interrogation of Survivors
	January, 1944
	NAVAL INTELLIGENCE DIVISION,
	ADMIRALTY, S.W.1.
	N.I.D. 08409/43.

 

	ii
	The following report is compiled from information derived from prisoners of war.  The statements made cannot always be verified; they should therefore not be accepted as facts unless they are definitely stated to be confirmed by information from other sources.

 

	iii
	CONTENTS
	_______
	Page I.   Introductory Remarks       (i)  General;  (ii)  Commanding Officer;  (iii)  First Lieutenant;  (iv)  Second Lieutenant;  (v)  Engineer Officer;  (vi)  Surgeon Lieutenant;  (vii)  Ship's Company;  (viii)   Equivalent Ranks.   1             II.   Details of "U 536 "   2     (i)  Type;  (ii)  Tonnage;  (iii)  Builders;  (iv)  Yard Number;  (v)  Armament (a)  Guns, (b)  Ready use Ammunition, (c)  Torpedo Tubes, (d)  Torpedoes, (e)  Anti-Escort Mines;   (vi)  Propulsion;  (vii)  G.S.R.;  (viii) Radar;  (ix)  R.D.B.;  (x)  S.B.T.;  (xi)  Hydrophones;  (xii)  Echo Sounder;  (xiii)  S.T. ("U.T.");  (xiv)  W/T Equipment;  (xv)  Camouflage;  (xvi)  Rubber Dinghies;  (xvii)  Badge;  (xviii)  Flotilla;  (xix)  Field Post Number.           III.   Second and Last Patrol of "U 536 "   4         IV.   Sinking of "U 536 "   6         V.   General Remarks on U-Boats   5     (i)  Contact-keeping by Aircraft;  (ii)  U-Boat Group Tactics;  (iii)  Escort through the Bay of Biscay;  (iv)  Tactics against Aircraft Attack;  (v)  Tactics when Refuelling;  (vi)  U-Boat Types:  (a)  300-ton U-Boats, (b)  Type VII F, (c)  Type IX D2, (d)  Type X, (e)  New Type Blohm & Voss U-Boats, (f)  "Schwarzes" U-Boat;  (vii)  G.S.R.;  (viii)  "Main" Receiver;  (ix)  Detection of U-Boats;  (x)  British Depth Charges;  (xi)  Steel Torpedo Tubes;  (xii)  Replacement of Unsuccessful C.O.'s;  (xiii)  U-Boat Losses.           VI.   Bases   9     (i)  France;  Lorient;  (ii)  Germany;  (a)  Cuxhaven, (b)  Stettin.           VII.   Miscellaneous Remarks   9     (i)  Dönitz's H.Q.;  (ii)  Goliath Transmitting Station.           ______________________                         APPENDIX "A."  Building and Working up of "U 536 "   10                         APPENDIX "B."  First Patrol of "U 536 "   10     (i)  First Patrol;  (ii)  Second Patrol.                           APPENDIX "C."  Nominal Roll of "U 536 "   11     (i)  Survivors;  (ii)  Casualties;  (iii)  Total Crew.
	(C51401)                                                                                                                             B2

 

	1
	REPORT  ON  INTERROGATION  OF  SURVIVORS  FROM    "U 536, " A 740-TON
	U-BOAT,  SUNK BY H.M.S. "NENE" ON 20th NOVEMBER, 1943
	______________________
	I.  INTRODUCTORY REMARKS
	(i)  General
	"U 536," a 740-ton U-Boat commanded by Kapitänleutnant Rolf Schauenburg, was sunk at 0247 on 20th November, 1943, by H.M.S. "Nene," assisted by H.M.C.S. "Snowberry" and H.M.C.S. "Calgary," in position 43° 50' N., 19° 39' W.  Seventeen survivors, including the commanding officer, were picked up.
	The U-Boat was on her second patrol and had been at sea since 29th August, 1943.  She had proceeded to the St. Lawrence to pick up escaped U-Boat prisoners, but was discouraged by the presence of Canadian warships and made off.  Subsequently, she operated off Halifax, mostly without success.  When sunk she was returning to base having been ordered to take part in a convoy attack on the way.
	(ii)  Commanding Officer
	Kapitänleutnant Rolf Schauenburg is aged thirty.  He joined the German Navy in 1934 and had trained in "Schlesien," in which ship he visited Great Britain at the time of the Coronation and, later, Canada.  In 1938 he was divisional officer at the Naval School, Flensburg-Mürwik.  He then joined "Graf Spee," was on board during the Battle of the River Plate and was subsequently interned in the Argentine.  He escaped and, according to his Second Lieutenant, travelled round the South American Continent as a cloth dealer, having many influential friends.  It was stated that he was twice recaptured, but released at the request of the German Consul.  His Second Lieutenant added that the German High Command wished him to remain in South America and collaborate with the German Consuls there, but the Continent apparently grew too hot for him and it was decided that he should return.  He said that Schauenburg finally flew back to Germany, starting from Chile in an Italian aircraft.  He had arrived in Germany by January, 1941.
	Before joining the U-Boat arm, Schauenburg was said to have served in minesweepers.  He also admitted to having assisted in the interrogation of British Air Force Officers, but said that he was only a guest at the time.
	His brother, Dietrich, was said to be serving as First Lieutenant in the U-Boat commanded by Kruschka.
	Schauenburg was a great stickler for discipline and insisted on the standard of surface units, for which he was much criticised by his men.  He would not allow a speck of dirt in his ship and, on return from his first patrol, each and every member of the ship's company had to be washed and shaved, in spite of the custom of U-Boat men to enter port covered with the grime of weeks at sea.  He had made his First Lieutenant responsible for the cleanliness on board and was often heard telling this officer, who had just become engaged to be married, that he would not give permission for him to marry if he found any dirt.  His men also criticised him for listening in to foreign broadcasts, especially those from South America and Great Britain, which meant constantly disturbing the W/T personnel.  One rating said that he was always talking of giving his life for the "Vaterland," but never, by any chance, of sinking a merchantman.  Nevertheless, his men respected his strong and determined character.  His Second Lieutenant described him as a fanatical and idealistic Nazi.
	Interrogators found him pleasant to talk to on general subjects, but adamantly security conscious on service matters.  He speaks fluent English and Spanish.
	(iii)  First Lieutenant
	The First Lieutenant, who survived, is Oberleutnant zur See Wolfgang von Bartenwerfer.  He is aged twenty-four and joined the Navy in October, 1939.  His men considered him to be a capable officer and he was shortly to have taken a U-Boat Commanding Officers' course.
	He was security conscious and unprepossessing.
	(iv)  Second Lieutenant
	Leutnant zur See Günther Freudenberg, aged twenty, also survived.  He joined in April, 1940, and served in destroyers as an ordinary seaman, before becoming an officer cadet in 1941.  He was then drafted to an A/S flotilla, based on Northern Norway.  Early in 1942, as a Midshipman, he made a patrol in a 500-ton U-Boat.
	This prisoner is in the family of the large leather manufacturing firm of Freudenburg, which had many international connections.  His father was killed near Paris in 1940, while serving as a captain
	(C51401)                                                                                                                              B3

 

	2
	in the artillery.  The latter had told his son that it was not necessary to join the Nazi Party; it was enough to be a good German.  Freudenberg seemed to take it for granted that Germany would eventually lose the war.
	He was quite pleasant and well-mannered, but not forthcoming on service matters.
	(v)  Engineer Officer
	The engineer officer was Kapitänleutnant (Ing.) Willi Kujas.  He did not survive.  It is known that he joined the Navy in 1936 and had made six patrols in "U 432," from august, 1941, until December, 1942.  (See C.B. 04051 (64).)  Prisoners said that he had been awarded the Iron Cross, 1st Class.  He was popular on board and considered an efficient officer.
	(vi)  Surgeon Lieutenant
	Nothing is known of Oberassistentarzt Dr. Borgmann.  He was seen in a rubber dinghy by survivors, but was not picked up by H.M. Ships.
	(vii)  Ship's Company
	"U 536's" complement was 55 of which 14 ratings survived.  In spite of their Commanding Officer, they were as a whole less security conscious than other recently captured prisoners.  However, the sum of their knowledge and experience was not considerable, none of the more senior ratings having survived.  The average of these 14 prisoners was just over 20 1/2 years.
	(viii)  Equivalent Ranks
	The following are the Royal Navy Equivalents of German Naval ranks used in this report:
	Korvettenkapitän Lieutenant-Commander. Kapitänleutnant Lieutenant. Oberleutnant zur See Sub-Lieutenant. Leutnant zur See Junior Sub-Lieutenant. Oberfähnrich zur See Senior Midshipman. Fähnrich zur See Junior Midshipman. Marinestabsarzt Surgeon-Lieutenant.
	The suffix (Ing.) after a German rank in place of "zur See" denotes and Engineer Officer.  The suffix "der Reserve" denotes a Reserve Officer.
	II.  DETAILS OF "U 536"
	(i)   Type VII C.       (ii)   Tonnage 740.       (iii)   Builders Deutsche Werft, Hamburg.  (Commissioned 13th February, 1943).       (iv)   Yard Number 353 or 354.       (v)   Armament (a)  Guns:  One 105 mm. (4.14 in.) forward, one 20 mm. (0.79 in.) quadruple mounting on additional lower gun platform, two 20 mm single mountings on "bandstand."  Two twin machine-guns, type 81, could be mounted on the bridge, but were never used.  Prisoners said that the additional lower gun platform was fitted after the first patrol.     (b)  Ready-use Ammunition:  Twenty-eight rounds of 105 mm. ammunition were stowed between the upper deck and the pressure hull abaft the gun.  Each round had an individual water-tight and pressure proof container.  They were stowed seven rounds abreast in four tiers.  According to one prisoner these rounds were all A.A. shells.  One pressure proof container per gun of 20 mm. ammunition was stowed near or attached to each 20 mm. gun.     (c)  Torpedo Tubes:  Four forward and two aft.  They were made of bronze.     (d)  Torpedoes:  On her first patrol "U 536" carried fifteen ordinary electric torpedoes.

 

	3
	On her second patrol she had an outfit of twenty, including six air torpedoes in upper deck containers.  About six of the torpedoes carried inboard were fitted with F.A.T. mechanism.  Pi. 2 and Pi 3 pistols were carried.  (N.I.D. Note.  Pi. 3 is possibly a magnetic and impact pistol for use in air torpedoes.  It was described in C.B. 04051 (92), Section VIII.)  One prisoner said that "U 536" had three less than her full outfit of torpedoes on the last patrol, because of the additional amount of A.A. ammunition which was carried.     (e)  Anti-Escort Mines:  All prisoners denied knowledge of the use of any such mines, although one spoke of the possibility of developing them along the lines of submarine emergency rescue buoys.  They were definitely not carried by "U 536."  (N.I.D. Note.  This type of weapon was mentioned in C.B. 04051 (72), page 12.)       (vi)   Propulsion (a)  Diesels:  Two M.A.N. 9-cylinder four-stroke diesels, each developing 2,200 h.p. and fitted with exhaust turbine ("Buchi") superchargers.     (b)  Main Motors:  Siemens.       (vii)   G.S.R. Drum-shaped aerial on the port side of the bridge.  The receiver was a "Wanz" type, by Hagenuk.  The use of this G.S.R. was forbidden during the latter part of "U 536's" last patrol.       (viii)   Radar Mattress type reflector on the port side of the bridge immediately abaft the G.S.R. aerial.  This was fitted in Germany and was said to be similar in shape but larger than those fitted to U-Boats at French bases.  The dimensions were given as 6.5 ft. by 4.1 ft.  There were two rows of four vertical dipoles, one row for transmitting and one row for receiving.  Each dipole was 40 cm. (15.7 in.) long.  The reserve G.S.R. aerial on the back of this mattress reflector consisted of two small figures of eight.     Wavelength of Radar transmissions was given as 80 cms.     This set was by Gema.     On a visit to Berlin in August, Schauenburg was told by Dönitz that a Lichtenstein type set was to be fitted before the next patrol.  (N.I.D. Note.  Lichtenstein is a German Air Force Radar, which has been reported as fitted, in a modified form, in E-boats.)       (ix)   R.D.B. Fitted.  One prisoner thought about ninety balloons were carried and another said that during passage of the Bay of Biscay they were released ten at a time, whenever the U-Boat dived.  Balloons were described as being about 60 cms. (23 in.) in diameter and each had three strips of metal ribbon about 20 metres (65 ft.) long below it.  (N.I.D. Note.  Details of varying types of R.D.B. have been given in previous reports, see in particular, C.B.s 04051 (85), page 2 and 04051 (92), page 2.)       (x)   S.B.T. Fitted, but never used.       (xi)   Hydrophones Multi-unit type, by Atlas.       (xii)   Echo-Sounder By Atlas.       (xiii)   S.T. ("U.T.") By Elag.       (xiv)   W/T Equipment "Main" (Lorenz) H/F/ receiver carried on the last patrol and standard equipment as follows:             One 200-watt H/F/ transmitter (20-80 m.) by Telefunken.             One 150-watt, L/F transmitter by Telefunken.             One 40-watt emergency all-wave transmitter/receiver by Lorenz.             One all-wave receiver by Telefunken.               Two radio sets, one by Telefunken and the other by Radione; the latter in the Wardroom.               The intercommunication loud speaker system was by Siemens-Halske.               D/F gear was by Telefunken.               Aerials consisted of the normal jumping wires and D/F loop.
	(C51401)                                                                                                                         B4

 

	4
	(xv)   Camouflage On the first patrol "U 536" had her hull painted black and her bridge superstructure grey with a narrow black line painted round it.  Before her second patrol she was painted brownish-grey all over.       (xvi)   Rubber Dinghies Three eight-man and twenty-five one-man inflatable rubber dinghies carried.       (xvii)   Badge A broom sweeping away a half-sunken merchantman on a shield.       (xviii)   Flotilla Second, based Lorient.       (xix)   Field Post Number M.49397.
	III.  SECOND AND LAST PATROL OF "U 536"
	"U 536" Sails
	"U 536" sailed from Lorient at about 1700 on 29th August, 1943, in company with the U-Boats commanded by Kapitänleutnant Henke ("U 515") and Pfeffer ("U 170").  They were escorted by three or four small craft, probably minesweepers.
	The two other U-Boats parted company near the 100 fathom line, at a point known by the codename "Laterne."  Prisoners said that "U 515" developed engine trouble here and put back to Lorient.  She sailed again shortly afterwards.  "U 170" altered course to operate to the south, where she was to join "U 68."
	By dawn on 30 August, "U 536" was alone.  The 31st was uneventful.
	"U 536" is attacked by Aircraft
	The next evening when "U 536" had surfaced to recharge her batteries, she was attacked by a searchlight aircraft.  She opened fire and then dived as the aircraft dropped a stick of depth-charges.  They fell wide and the U-Boat escaped undamaged.
	(N.I.D. Note.  This was probably the attack by a searchlight Wellington "F" of 407 Squadron at 2230 on 1st September in position 46° 07' N., 9° 12' W.  The aircraft dropped six depth-charges).
	Passage of the Bay of Biscay
	Throughout her passage of the Bay of Biscay and until well out into the Atlantic, "U 536" remained submerged by day and only surfaced for the few hours necessary to charge her batteries at night.  Before each dive she released about ten Radar Decoy Balloons.  While on the surface she proceeded at about 10 knots, but her submerged speed did not average more than 2-3 knots.
	Her Destination
	It was intended that she should proceed towards the Caribbean, take over some 17 tons of fuel from another U-Boat, and then operate in that area.
	"Kiebitz" Operation
	Schauenburg was in Berlin during August and was informed by Dönitz that a U-Boat would pick up escaped prisoners from Canada.  If he was told that his own U-Boat might have to undertake this operation, he did not pass on the information to his officers.  When they sailed on patrol, "U 536's" ship's company did not even know that their commanding officer carried sealed orders and special codes.
	Before "U 536" was clear of the Bay of Biscay a signal was received from Control that the 500-ton U-Boat who was to have carried out the operation had been sunk by an aircraft in the Bay of Biscay.
	(N.I.D. Note.  This might have been the attack by Wellington "S" of 612 Squadron at 0523 2nd September in position 46° 53' N., 10° 32' W. or by "W" of 407 Squadron at 0241A 7th September in 45° 36' N., 10° 13' W.  The latter attack seems more likely.)
	It is not known what instructions were passed to "U 536" concerning the "Kiebitz" operation, as it was to be known, or to what extent Schauenburg could inform himself of this operation by means of the sealed orders given him at Lorient.  Schauenburg gave his men only a brief outline of the plan and said that they were to proceed on a special mission to pick up three escaped U-Boat prisoners from Canada, one of whom was a well-known ace, whom the crew presumed to be Kretschmer; some mention was also made of Dönitz's former adjutant.  (N.I.D. Note.  Korvettenkapitän Otto Kretschmer was commanding officer of "U 99," sunk on 17 March, 1941.  Dönitz's former adjutant is probably von Knebel-Döberitz, who was First Lieutenant in "U 99.")  Schauenburg informed his officers that

 

	5
	communication with the prisoners was to be established by wireless and showed them detailed charts of the area in which the rescue was to take place.  He warned the ship's company that two U-Boats had been sunk during similar attempts to rescue prisoners.
	(N.I.D. Note.  Kapitänleutnant Wolfgang Heyda, former commanding officer of "U 434," was recaptured on 27th September, 1943.  No further escapes were effected.)
	She Arrives in the St. Lawrence
	"U 536" set course for the St. Lawrence, in which area she arrived about 16th September, 1943.  Her orders were to tune in for communication with the escapees from 23rd September, 1943.  There was plenty of time for plans to be perfected.  The Second Lieutenant and a stoker were to go ashore in a dinghy with an outboard motor, carried specially for the occasion.  The whole adventure evidently appealed to the young officer, who, in the style of American gangster movies, designed for himself a special cap weighted with lead.  This he intended to wear ashore and, if accosted by anyone but the expected escapees, he would doff his cap politely, catching his interrogator a swipe across the jaw.
	Failure of Mission
	"U 536" was ordered to arrive in Chaleur Bay by 26th September; the escapees were not expected until the next day, or later.  She took up station some days earlier.  Throughout daylight she remained submerged and only surfaced for a few hours at night to recharge batteries; even then she trimmed right down to her bridge superstructure.  Once she picked up a signal, thought to emanate from the escapees, but when this was not repeated she became wary of a trap and made no reply.  At times "U 536" was only 200 yards off shore.  Schauenburg took every opportunity to examine the lie of the land through his periscope.  He became aware that the charts which had been supplied were out of date; where the chart showed only a solitary building was indicated, he observed a number of buildings.  Since the position of the rendezvous was partly to be fixed by the so-called solitary building, the matter was vital.
	Early on the night of 26th September, Schauenburg decided to move out of Chaleur Bay in order to charge batteries which were then running low.  Just before submerging, in order to leave the Bay, he sighted some warships in the vicinity.  According to the Second Lieutenant a destroyer and a corvette were inside Chaleur Bay and the Commanding Officer thought he saw six warships further out.  He said that the corvette stopped and took up position off a point which was to have been the rendezvous with the escapees.
	Instead of submerging Schauenburg continued to observe the movements of the warships through his periscope.  After some hours the corvette, lying off the point, moved off and was relieved by another and it became abundantly clear to him that the German plans were known.
	"U 536" submerged and throughout 27th September she lay on the bottom.  Schauenburg decided that it was hopeless to try to effect the rescue and that his duty was only to bring his U-Boat back to safety.  He appreciated that British warships could not make an attack in the shallow waters of Chaleur Bay, without risking damage to themselves and would, therefore, attempt to drive the U-Boat into deeper waters before depth-charging her.  In spite of two ships patrolling in the Bay he therefore remained in the shallowest water.
	During the night of 27th/28th September "U 536" left the Bay at slow speed, submerged to about 20 metres (65 ft.).  Throughout her passage, hunting craft could be heard in the vicinity and on one occasion it was thought that the U-Boat had been detected as one ship followed her for some time.  Depth-charges were heard at a distance, but she sustained no damage.
	(N.I.D. Note.  Warships made an attack on a contact off Chaleur Bay during the night of 27th/28th September, 1943.)
	Later, when asked by Control the reason for the failure of his mission, Schauenburg signalled that warships had been waiting at the rendezvous.
	"U 536" attacks a Destroyer
	On reaching the Cabot Straits "U 536" sighted a destroyer lying on her course.  As no other warships appeared to be in the neighborhood, Schauenburg considered this a good opportunity to attack and fired three torpedoes, all of which missed.  No counter-attack developed, the destroyer appearing unaware of the U-Boat's presence.  "U 536" proceeded towards the open sea.
	She operates off Halifax
	She patrolled off Halifax and along the Canadian coast for three or four weeks.  She sighted a good deal of shipping, but was consistently unable to manoeuvre into an attacking position.
	She claims the Sinking of a 10,500-ton Merchantman
	In early October she carried out an attack on a 10,500-ton merchantman, which she claims to have sunk.  This ship was sighted early one morning and two salvoes of two torpedoes were fired without result.  Prisoners believe that three of these torpedoes, which were all electric, had hit their target and failed to explode.  They attributed this to faulty pistols and careless adjustment of the torpedo angling gear.  According to prisoners a fifth electric torpedo fitted with F.A.T. mechanism was fired, found its mark and exploded.
	(N.I.D. Note.  There is no record of any such attack or sinking in the Halifax area during the month of October, 1943.)

 

	6
	She makes Further Attacks
	"U 536" made two more attacks, both of them unsuccessful, before leaving the area.  She sighted a fast independently routed ship, estimated at 23,000 tons.  Two air torpedoes were fired, but both missed.  She later attacked another and much smaller merchantman with two electric torpedoes, which again failed to score.
	"U 536" Sets Course for Base
	During the past weeks danger from aircraft had prevented "U 536" from striking down torpedoes from her upper deck containers, so that there remained only two in her bow tubes, one of there being fitted with F.A.T. mechanism.  Her fuel was running short and she requested permission to return.  She was ordered back to base, and to make use of any opportunity to attack shipping on the way.
	She joins a Convoy Attack
	During the third week in November, "U 536" fell in with other U-Boats, assembling for an attack on a convoy.  In spite of having only about 30 tons of fuel remaining, she was ordered to join in the attack.  Prisoners said that four groups totalling about forty U-Boats were taking part.  The Groups were known by the names "Schill 1," "Schill 2," "Schill 3" and "Eisenhardt."  They believed that about 10 U-Boats were carrying Gnats, which they had been ordered to try out in this attack.  Contact-keeping with the convoy was by German shore based aircraft (see also Section V).
	A Depth-charge Attack
	Before midnight on 17th/18th November, "U 536" was proceeding surfaced to make contact with the convoy, when she was illuminated by a searchlight and dived.  A depth-charge attack followed, about fifty explosions being heard in the U-Boat; but they were all at some distance and no damage resulted.
	(N.I.D. Note.  H.M.S. "Foley," escorting SL.139/MKS 30, made six attacks at about 2204 on 17th November.)
	Other U-Boats
	Among U-Boats said to be operating in the attack were those commanded by; Cremer ("U 333"), Davidson, Dobbert, Heller, Henke ("U 515"), Müller, Poel, Pfeffer ("U 170"), Rahn, Stahl ("U 648"), Struckmeier ("U 608") and Zurmühlen ("U 600").
	IV.  SINKING OF "U 536"
	During the evening of 19th November, 1943, "U 536" closed the convoy.  It was known that another U-Boat was operating on her port beam.  Prisoners suggested that this was the U-Boat commanded by Stahl ("U 648").  "U 536's" hydrophones picked up the noise of gunfire and of the other U-Boat diving.  Later she heard depth-charge attacks, but they were all at some distance from herself, and they were thought to have been directed against her companion.
	(N.I.D. Note.  H.M.S. "Nene" obtained a Radar contact at 2100 on 19th November.  Depth-charge attacks followed.  H.M.S. "Nene" and H.M.C.S. "Snowberry" obtained and A/S contact at 2349.  Further attacks were made at 2357 on the 19th and 0021 on 20th November by H.M.S. "Snowberry.")
	Quite suddenly an Asdic ping was heard in "U 536" and a pattern of depth-charges followed immediately.  The U-Boat had been at a depth of about 160-190 metres (525-625 ft.) and was not expecting the attack.  Considerable confusion was caused; she went badly down by the stern, and the lights failed.  A fuse-box gave off a burst of flame and yellow smoke formed.  Prisoners were unable to explain why the U-Boat was down by the stern, although it was suggested that the watertight stern had been damaged; they said there was no evidence of water entry.  Several of them expressed the opinion that the depth-charges used were of a new and more powerful type.
	(N.I.D. Note.  "Snowberry" and "Nene" proceeded to carry out "Observant" at 0041.  At 0110 an A/S contact was obtained and at 0118 "Nene" attacked with a deep pattern.)
	In "U 536" the Engineer Officer informed his Commanding Officer that he was unable to trim the boat and the order was given to surface.  All hands assembled in the control room preparatory to abandoning ship.  There were some casualties owing to gunfire when the U-Boat broke surface, a direct hit being obtained on the bridge.  Most of the ship's company made good their escape in dinghies and seventeen of them were later picked up.  The U-Boat was left underway with port helm on and all vents open; no scuttling charges were fired.
	(N.I.D. Note.  The U-Boat surfaced and was at once attacked by gunfire from "Snowberry."  "Nene" brought her guns to bear immediately afterwards and H.M.C.S. "Calgary" was in action a few minutes later.  The crew commenced to abandon the U-Boat, which was down by the stern.  She continued to move through the water at 3-4 knots, turning to port.  She finally sank by the stern at 0247 in position 43° 50' N., 19° 39' W.  Survivors were picked up by H.M.C.S. "Snowberry," H.M.S. "Tweed" and H.M.C.S. "Calgary.")

 

	7
	V.  GENERAL REMARKS ON U-BOATS
	(i)  Contact-keeping by Aircraft
	During the attack on the convoy in the course of which "U 536" was sunk, contact had been maintained, and U-Boats homed on to the convoy, by aircraft.  The aircraft engaged in this operation were said to be long range He.177 and Ju.290.
	Prisoners stated that the U-Boats received a code signal from Control instructing then to listen in on a certain wavelength, which changed at certain hours during the day.  At known intervals the aircraft transmitted their positions and bearing from the convoy, as well as details of the convoy itself, such as the number of merchant ships and escorts and their course and speed.  These signals were usually made in plain language.  The frequency used was said to be between 250-600 kc/s.
	When a U-Boat picked up bearing signals from a contact-keeping aircraft, she reported her position by short signal to Control, stating that she had the bearing of the aircraft.  Having noted the positions of all U-Boats in the area, Control signalled details of the convoy's course and speed.
	It was stated that aircraft also dropped contact-keeping flares near the convoy which were said to burn for three to four hours.  They said that this practice is not favoured by Control, as only U-Boats in the immediate vicinity benefit from the flares.  In order that other U-Boats may be directed to the scene, the making of homing signals is considered necessary.
	(ii)  U-Boat Group Tactics
	Prisoners from "U 536" said that there is a standard formation laid down by Control, for U-Boats proceeding in groups of three.  The S.O.s U-Boat proceeds ahead, the third boat takes station astern and the second is disposed abeam to port or starboard between the other two.  When an aircraft attacks from dead ahead and there is sufficient time to manoeuvre, U-Boats continue on their course and open fire.  If an attack develops on the bow, U-Boats may turn into the attacker; if attacked on the quarter they turn towards the aircraft.  (See the account of the action on 5th July, 1942, in Appendix "B".)
	U-Boats are said to carry green yellow and red flags for use when in group formation.  The green flag indicates G.S.R. contact has been received, or that U-Boats are to remain surfaced after an aircraft has been sighted.  The yellow flag signifies "Stand by to dive," the other U-Boats indicating their readiness by waving their yellow flag.  The waving of the red flag is the operative order to dive.
	(iii)  Escort through the Bay of Biscay
	The Second Lieutenant of "U 536" said that while he was at sea on the last patrol, probably in November, 1943, the routine for escorting U-Boats in and out of their Atlantic bases was altered.  He said that the old rendezvous positions, known by names "Laterne" and "Herz," were no longer used.  Whereas formerly U-Boats were escorted as far as the 100-fathom line, at which point returning U-Boats were also met, escorts now only proceed as far as the 27-fathom (50 metres) line.  He also said that the approved distances between individual U-Boats and their escorts had been altered, but could give no further details.  (N.I.D. Note.  The Captain of "U 523" mentioned that "Sperrbrecher" were sweeping for mines up to a depth of 25 fathoms only; see C.B. 04051 (86), page 12.)
	(iv)  Tactics against Aircraft Attack
	"U 536" survivors indicated that it was the policy of their Commanding Officer to engage an attacking aircraft with Flak during the first run-up, and then to crash-dive as the aircraft was circling to make a second attack.
	They indicated that this is becoming a general practice with many U-Boats, and that it is usual to increase speed to about 18 knots, to give a greater manoeuverability, and to enable them to crash-dive more quickly.  This procedure is apparently proving very satisfactory.
	Another prisoner said that against searchlight aircraft gunners did not aim directly above the beam, but tried to lead it, firing rather above it than up it.
	In connection with aircraft attack, it was also stated that quite a good field of forward fire can now be obtained by the guns on the "bandstand," as the "bandstand" has been raised about 30 cms. (12 ins.), enabling forward fire from these positions however low an aircraft attempts to attack from ahead.
	(v)  Tactics when Refuelling
	"U 536" survivors said that supply U-Boats and operational U-Boats attacked by aircraft when engaged in refuelling had orders requiring the supply U-Boat to crash-dive immediately, while the operational boat engaged the aircraft, at least long enough to allow the supply boat to reach a depth of 60 metres (approximately 200 ft.)
	(vi)  U-Boat Types
	(a)  300-ton U-Boats.  Are fitted with M.W.M. Diesels.
	(b)  Type VII F.  "U 536's" Second Lieutenant had seen U-Boats of this type in Kiel, where he believed they are being built.  He said that although they are outwardly of the same appearance as

 

	8
	Type VII C, they are really 8 metres (26 ft.) longer and slightly broader in the beam.  They have the same number of torpedo tubes, but a slightly larger radius of action.
	(N.I.D. Note.  This type was somewhat differently described in C.B. 04051(90), page 4.)
	(c)  Type IX D2.  1,200-ton U-Boats of this type are said to be exactly 8 metres (26 ft.) longer than type IX C (740-ton) U-Boats.  They are similar in both the number of torpedo tubes and their armament to type IX C U-Boats.
	(d)  Type X.  Type X, 1,600-ton minelayer/supply U-Boats are built at Kiel.  Nearly all U-Boats of this type are at present being used as supply U-Boats and not as minelayers.
	(e)  New Type Blohm & Voss U-Boats.  According to "U 536's" Second Lieutenant, the Blohm & Voss yards, under the direction of Dr. Frahm, are working full out on the development of U-Boats with a faster submerged speed.  The prisoner thought that they would have no propellers and would be driven by some kind of gas.  He mentioned a surface speed of not more than 8 knots, but a submerged speed of about 25 knots.  He said that in German Naval Officer circles, it is not considered that this type of U-Boat will be ready for operation in this war.  (N.I.D. Note.  It is quite possible that either an internal combustion engine or a high-pressure vapour engine (e.g., a large torpedo type) could be developed; it would be very unlikely to lack a propeller for at such speeds other propulsion systems are not so efficient.)
	(f)  "Schwarzes" U-Boat.  The same prisoner said that there is at present much rumour of a U-Boat which can absorb all Radar beams, known as a "Schwarzes (Black) U-Boat.  He did not believe that trials of this type would be completed before the end of the war.
	(N.I.D. Note.  Prisoners from "U 470" also made some mention of a "Schwarzes U-Boat".  "U 470" was stated to be rubber covered and painted black.  She was stated to have carried out trials at Sönderborg, Denmark (N. of Kiel Bay) with this covering for over a year.  Such trials are considered unlikely to be successful against Asdic or Radar.  See also C.B. 04051(84), Appendix "A.")
	(vii)  G.S.R.
	A Leading Telegraphist from "U 536" had heard that the "Naxos" G.S.R. was only a temporary expedient, and that it would be replaced by a still newer set, referred to as the "Borkum," as this became available in sufficient quantities.  He had heard that the "Borkum incorporated all of the features of the "Naxos," but that it was an improvement and a much more finished apparatus.  This was corroborated by the Second Lieutenant.
	Another Leading Telegraphist from "U 536" said that he had intercepted a signal some time in October from another U-Boat stating that the "Naxos" was proving very successful under operational conditions.  (N.I.D. Note.  "Naxos" G.S.R. was described in C.B. 04051(91), Section VIII.)
	(viii)  "Main" Receiver
	According to a Leading Telegraphist, this receiver has three switch positions, for C.W., I.C.W. and R/T reception.  He said that Schauenburg had forbidden the use of this receiver in the Bay of Biscay area, as he believed it radiated.  (N.I.D. Note.  See C.B. 04051(86), page 11.)
	(ix)  Detection of U-Boats
	It was once more evident from prisoners' statements that they feared detection through radiation either of their own W/T gear or of the U-Boat herself.  One prisoner mentioned that the use of the D/F loop had been forbidden for this reason.  The Second Lieutenant had noticed sparks emanating from between the D/F loop and the bridge faring and, after discussion with his brother officers, had come to the conclusion that, apart from any transmissions from W/T and similar gear on board, the U-Boat was radiating and thus betraying her position.
	(x)  British Depth-charges
	The Second Lieutenant of "U 536" stated that in German Naval Secret Orders British depth-charges are said to be inneffective when U-Boats reach a depth of 150 metres (500 ft.).  At a depth of 120 metres (400 ft.) the lethal range is given as 8 metres (26 ft.).
	(xi)  Steel Torpedo Tubes
	One of the "U 536" survivors stated that some U-Boats now under construction are being fitted with steel torpedo tubes, and that once the supply of the present bronze tubes is exhausted, steel tubes only will be installed.  (N.I.D. Note.  See also C.B. 04051 (86), page 2.)
	(xii)  Replacement of Unsuccessful C.O.s
	An Able Seaman from "U 732" said that any U-Boat Commanding Officer who fails to sink any vessels during five patrols is relieved of his commend and replaced by another officer.
	(xiii)  U-Boat Losses
	A "U 536" survivor said that the 2nd U-Boat Flotilla at Lorient had lost 36 boats during the last six months.

 

	9
	VI.  BASES
	(i)  France
	Lorient.  Personnel of the 2nd Flotilla are accommodated in "Lager Lemp," a camp situated in a wood about 20 minutes distant from the Pont-Scorff, north of Lorient.  The Officers' Mess is located in an old watermill on the shores of a lake.  The whole camp is very heavily camouflaged, so that although air-raid shelter are provided, U-Boat crews do not find it necessary to use them.
	It is absolutely forbidden to drink any unboiled water in Lorient, owing to the danger of contracting typhus.
	(ii)  Germany
	(a)  Cuxhaven.  This base was said to be considerably reduced in importance as a shipping centre since the outbreak of war.  All coastal artillery in the neighborhood had been withdrawn and probably transferred to the eastern front.
	(b)  Stettin.  It was stated that there was always a concentration of U-Boats at this base, since the Oderwerke are mainly engaged in U-Boat repairs.  U-Boats also come to this yard for overhaul after completing trials.
	VII.  MISCELLANEOUS REMARKS
	(i)  Dönitz's H.Q.
	Admiral Dönitz's H.Q. was said to have moved from Paris some time in September or October, 1942, and to be at present divided between the O.K.M. building in Berlin and Bernau, about 30 miles east of the Capital.
	The Chief W/T station was said to be at Bernau, its call-sign being "ADA."  The U-Boat operations room and certain other divisions were also thought to be located at Bernau.  (N.I.D. Note.  This W/T station is at Nauen, N.W. of Berlin.)
	(ii)  Goliath Transmitting Station
	This station was said to be situated in the neighborhood of Stendal, north of Magdeburg.  It was thought to be a 1,000 kw. station, which could transmit on various frequencies (unlike the stations Paris I and II).
	The aerial was said to be a 6 kilometre long complex.  (N.I.D. Note.  See also C.B. 04051 (84), page 7 and (88), page 7.)

 

	10
	APPENDIX "A."  BUILDING AND WORKING UP OF "U 536"
	Some members of "U 536's ship's" company were drafted to stand by the boat at the Deutsche Werft, Finkenserder, Hamburg, during November, 1942.  She commissioned on 13th January, 1943.
	Trials at the U-Boat Acceptance Command, Kiel, lasted nearly six weeks and were followed by silent running trials at Rönne in early March.  Thence "U 536" proceeded to the "Agru-Front," Hel.  She spent three days in the yards at Danzig before continuing to Pillau for tactical exercises.  On account of outstanding efficiency she accomplished the latter in the minimum time of ten days.
	Calling at Stettin on passage, "U 536" then returned to Hamburg for final adjustments; she arrived there in early April.  After five or six weeks in dock, she proceeded to Kiel, where she stayed under a week before sailing on her first patrol.
	APPENDIX "B."  FIRST PATROL OF "U 536"
	"U 536" sailed on her first patrol from Kiel on 1st June, 1943, and called for a few hours at Kristiansand S. before setting course for the "Rosengarten," Somewhere north of the Shetlands a British destroyer or corvette was sighted, but the U-Boat was not herself detected.
	Shortly after completing the passage of the "Rosengarten," on Whit Sunday (13th June), she was attacked by an aircraft.  Machine-gun fire was exchanged and the aircraft dropped bombs, which all fell ahead of the U-Boat.  She sustained no damage.
	(N.I.D. Note.  U.S. Catalina "K" of 84 Squadron attacked a U-Boat on 13th June in position 59° 05' N., 26° 07' W.  She made two attacks, both assessed as "no evidence of damage")
	With the U-Boats commanded by Ellmenreich ("U 535") and Pfeffer ("U 170").  "U 536" was due to proceed direct to Lorient to have new A.A. armament fitted.  They were all, therefore ordered to refuel a number of other U-Boats.  In company with the two other U-Boats.  "U 536" proceeded to an area south of the Azores where they met and refuelled the U-Boats commanded by the following officers:
	Dahlhaus.
	Uphoff ("U 84").
	Janssen.
	Mumm ("U 594").
	Bartke.
	Prisoners said that the U-Boat commanded by Mumm was proceeding to the Mediterranean.
	While still in this area, repairs were carried out to "U 535," who had been attacked in the "Rosengarten" and sustained considerable damage.  Her watertight stern was practically blown away and she had two tears in her pressure hull amidships, which were welded.
	Towards the end of June, the three U-Boats set course for base.  They approached the Bay of Biscay from due West, intending to enter just north of Finisterre and to hug the Spanish coast for a short distance before altering towards Lorient.  They were attacked by aircraft when they were several hundred miles from the Spanish coast.  Prisoners stated that at least one aircraft when they were several hundred miles from the Spanish coast.  Prisoners stated that at least one aircraft was engaged before the U-Boats dived to safety.
	The group was again attacked on the morning of 5th July, without success.  (N.I.D. Note.  Sunderland "H" of 10 Squadron, R.A.A.F., attacked three U-Boats at 0929 on 5th July, in position 43° 36' N., 10° 25' W.)  During the same evening, while still some hundred miles from the Spanish coast, another aircraft attack developed.
	The U-Boats were proceeding in formation with "U 536" leading, "U 535" second on her port quarter and "U 170" following astern.  The aircraft dived from right ahead and, according to one prisoner, intense and accurate fire from the nose gunner, forced the gun's crews in "U 536" to take cover.  It flew right over the U-Boat with bomb doors open, but nothing was dropped, and as it turned to make another run in, Schauenburg, the Senior Officer, gave the order for all three U-Boats to dive.  Up to this point the tactics employed had been those laid down by Control for U-Boats proceeding in groups (see Section V).  While crash-diving the explosion of depth-charges was heard in "U 536."
	(N.I.D. Note.  Liberator "G" of 53 Squadron attacked a group of three U-Boats at 1704 on 5th July.  During its first run in, all U-Boats turned sharply to starboard while firing with cannon and machine-guns, thus making the attack abortive.  On the second run in, the aircraft's depth-charges failed to release.  It made a third attack, by which time the U-Boats, which had been turning to port to keep beam on, were on a course of 360° and had lost their initial V formation.  The aircraft dropped eight Mark XI Torpex depth-charges from 50 ft. set to shallow depth, on the second U-Boat in line, which was still surfaced.  The stick appeared to have overshot, the first depth-charge exploding very close to the U-Boat's bow.  The U-Boats were last seen in line ahead, course 30°, with one which seemed to be lagging astern.)
	Once submerged, "U 536" established contact with "U 170" by "U/T."  She could not, however, get any reply from "U 535."  The two U-Boats surfaced some five hours later and searched for a trace of their companion.  None was found and they presumed that she had been sunk, as in her already damaged condition she could not have withstood attack.  Prisoners said that at base "U 535" was later announced as "presumed lost."
	The two other U-Boats proceeded direct to Lorient, where they arrived on 9th July.

 

	11
	APPENDIX "C."  NOMINAL ROLL OF "U 536"
	(i)  Survivors:
	Name Rank English Equivalent Born Schauenburg, Rolf Kapitänleutnant Lieutenant 30.  5.13 von Bartenwerfer, Wolfgang Oberleutnant zur See Sub-Lieutenant 7.  7.19 Freudenberg, Gunther Leutnant zur See Junior Sub-Lieutenant 16.  9.23 Thelen, Hans Bootsmannsmaat Leading Seaman 17.  2.22 Lubsch, Helmut Maschinenmaat Leading Stoker and E.R.A. 5th Class. 2.11.20 Dillschneider, Robert Funkmaat Leading Telegraphist 15.10.21 Steinbach, Fritz Matrosenobergefreiter Able Seaman 27.10.23 Everwien, Harm Matrosenobergefreiter Able Seaman 2.11.20 Schenkel, Heinz Matrosenobergefreiter Able Seaman 26.  1.23 Dröszler, Georg Maschinenobergefreiter Stoker, 1st Class 22.  4.22 Kaiser, Wilhelm Matrosengefreiter Able Seaman 26.  7.21 Paul, Wilhelm Matrosengefreiter Able Seaman 9.  5.24 Arnold, Franz Matrosengefreiter Able Seaman 27.  1.22 Moritz, Gerhard Maschinengefreiter Stoker, 1st Class 13.  2.23 Meyer, Wilhelm Maschinengefreiter Stoker, 1st Class 4.  4.24 Kern, Heinz Funkgefreiter Telegraphist 22.  9.22 King, Rudolf Mechanikergefreiter Able Seaman (S.T.) 5.  1.24
	Officers . . 3 Chief and Petty Officers . . - Men . . 14     17
	(ii)  Casualties:
	Kujas, Wilhelm Kapitänleutnant (Ing.) Lieutenant (E) - Borgmann, Dr. Oberassistenzarzt Surgeon-Lieutenant - Mark, Karl Obermaschinist Chief Stoker and Chief E.R.A., 1st or 2nd Class. - Dehmel, Max Obermaschinist Chief Stoker and Chief E.R.A., 1st or 2nd Class. - Hoefer, Ernst Obersteuermann C.P.O. (Navigation - Schuster, Heinz       | Petty Officers, not known what branch. - Sienimus, Max        | - Ulich, Gerhard Bootsmannsmaat Leading Seaman - Bastel, Franz Maschinenmaat Leading Stoker and E.R.A., 5th Class. - Kuhr, Fritz Maschinenmaat Leading Stoker and E.R.A., 5th Class. - Hossfeld, Fritz Maschinenmaat Leading Stoker and E.R.A., 5th Class. - Abraham, Seigfried Maschinenmaat Leading Stoker and E.R.A., 5th Class. - Kinzinger, Hermann Funkmaat Leading Telegraphist - Boehm, George (Torpedo) Mechanikersmaat L.T.O. - Pietreck, Heinz Matrosenobergefreiter Able Seaman - Bibovski, Werner Maschinenobergefreiter Stoker, 1st Class - Metzner, Kurt Maschinenobergefreiter Stoker, 1st Class - Lienhart, Rudolf Maschinenobergefreiter Stoker, 1st Class - Heinick, Hans Maschinenobergefreiter Stoker, 1st Class - Rothermund, Hans Maschinenobergefreiter Stoker, 1st Class - Ruckstroth, Walter Matrosengefreiter Able Seaman - Brunner, Heinz Matrosengefreiter Able Seaman - Braun, Ernst Matrosengefreiter Able Seaman - Klotz, August Matrosengefreiter Able Seaman - Boxheimer, Hans Maschinengefreiter Stoker, 1st Class - Menkel, Georg Maschinengefreiter Stoker, 1st Class - Sieben, Heinz Maschinengefreiter Stoker, 1st Class - Junger, Horst Maschinengefreiter Stoker, 1st Class - Block, Ewald Maschinengefreiter Stoker, 1st Class - Wiesmeier, Rudolf Maschinengefreiter Stoker, 1st Class - Kaltmeier, Rudolf Maschinengefreiter Stoker, 1st Class - Schwarz, Franz Maschinengefreiter Stoker, 1st Class - Elfner, Franz Funkgefreiter Telegraphist - Heinhold, Rudolf (Torpedo) Mechanikergefreiter Able Seaman (S.T.) - Freiwald, Hans (Torpedo) Mechanikergefreiter Able Seaman (S.T.) - Werner, Otto (Art.) Mechanikergefreiter Able Seaman (S.G.) - Raith, Heinz Matrose I Ordinary Seaman -
	Officers . . 2 Chief and Petty Officers . . 6 Men . . 30     38
	(iii)  Total Crew:
	Officers . . 5 Chief and Petty Officers . . 6 Men . . 44     55
	(C51401)    500    2/44

 

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