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                                                                                                                 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 (91)
"U 340"
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.



          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.  



Attention is called to the penalties attaching to any infraction of the
Official Secrets Acts.
C.B.  04051 (91)
"U 340"
Interrogation of Survivors
January, 1944
  N.I.D. 08409/43.  


          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.  


  Introductory Remarks  
  Details of "U 340"  
    (i)  Type;  (ii)  Tonnage;  (iii)  Building Yard;  (iv)  Armament;  (v)  Engines;  (vi)  S.B.T.;  (vii)  R.D.B.;  (viii)  Radar;  (ix)  G.S.R.;  (x)  W/T Equipment;  (xi)  Dinghies;  (xii)  Distiller;  (xiii)  Visual Acuity Pills;  (xiv)  Badge;  (xv)  Base;  (xvi)  FLotilla.  
  Third and Last Patrol of "U 340"  
  Sinking of "U 340"  
  General Remarks on U-Boats  
    (i)  Additional Fuel in 500-ton VIIC U-Boats;  (ii)  Extra Look-outs in U-Boats;  (iii)   U-Boat with 40-mm. (1.57-in.)  Flak Armament;  (iv)  M.A.N. Engines no longer fitted to U-Boats;  (v)  K.D.B. Hydrophones no longer fitter to Operational U-Boats;  (vi)  Sonic Telegraphy (German U/T);  (vii)  Method of Firing the 20-mm. (0.79-in.) Quadruple Gun.  
  U-Boat Bases  
    St. Nazaire.  
  U-Boat Tactics  
    (i)  Action Tactics;  (ii)  Navigational Tactics;  (iii)  Passage of the Straits of Gibraltar.  
  G.S.R. Equipment in U-Boats  
    (i)  "Naxos";  (ii)  "Wanz."  
  Miscellaneous Remarks  
    (i)  German War Casualties;  (ii)  W/T Personnel at U-Boat H.Q.  
                APPENDIX "A."  Building and Working up of "U 340"
                APPENDIX "B."  Previous Patrols of "U 340"
    (i)  First Patrol;  (ii)  Second Patrol.  
                APPENDIX "C."  Nominal Roll of "U 340"
    (i)  Survivors;  (ii)  Casualties;  (iii)  Total Crew.  
  (C51296)                                                                                                                             B*  


          "U 340," one of five U-Boats attempting to enter the Mediterranean at the time of her sinking, was scuttled at 0500 on 2nd November, 1943, after four depth-charge attacks by H.M.S. "Fleetwood" between 2254 and 2357 on 1st November in position 35° 49' N., 5° 14' W. off the Mediterranean coast of Spanish Morocco.  
          The boat had been harassed for three days prior to the sinking by aircraft and surface vessel attacks.  The batteries were badly run down, and when the supply of air began to give out during the long period of submersion following the final attack, the Commanding Officer, Oberleutnant zur See Hans Joachim Klaus, called his crew together and told them he was going to surface and scuttle to give them a chance of reaching the Spanish shore.  
          Survivors were picked up by Spanish fishing vessels about four hours after abandoning their scarcely damaged boat, and were loud in their complaints at having been taken off the Spanish vessels by H.M.S. "Fleetwood."  
          Only one man was missing from the complement of forty-nine, and the remainder thought that he had probably managed to reach the coast independently, as he has last been seen in a rubber dinghy.  The survivors proved generally security conscious, with one or two notable exceptions.  
          About fifteen members of the crew had joined the U-Boat just before her last patrol.  The men they replaced were said to have drunk polluted-water and contracted jaundice.  The average age of the junior ratings was twenty, while chief and petty officer survivors averaged twenty-seven years of age.  
          The Commanding Officer, Oberleutnant zur See Hans Joachim Klaus of the 1937 term, was civil but most uncommunicative.  While refusing to discuss the details of the sinking, he inferred that he would have expected to be repatriated to Germany if he had succeeded in reaching the Spanish coast.  His boat had made three patrols and had sunk nothing.  
          It was learnt from members of his crew that Klaus was a martinet and cordially disliked, and that "U 340" was the most unpopular boat in the St. Nazaire base.  Conscious efforts were made to avoid being drafted to her.  The camaraderie between officers and men usually noticeable in boats with popular Commanding Officers was completely lacking in "U 340," and survivors had nothing but criticism for the attitude of their officers in general and their behavior at the time of the sinking in particular.  
          The two twenty-one-year-old watch keeping officers were not an asset to their boat.  Hans Joachim Erben, the First Lieutenant, was a Nazi boor, and the second watch-keeping officer, Günter Eisenheim, a native of Danzig and a former art student, had distinguished himself by collapsing in one of the Spanish fishing vessels in front of several members of the crew, and was very much on his dignity as a result.  The Engineer Officer, Oberleutnant (Ing.) Hermann Grether, was impudent and uncommunicative on service matters.  
          Principal features of this report are:  
                  (a)  Further notes on U-Boat tactics (Section VII).  
                  (b)  New Type G.S.R. Equipment (Section VIII).  
          Equivalents of German and Royal Naval ranks used in this report are:  
Oberleutnant zur See
Leutnant zur See
Junior Sub-Lieutenant.
Oberfähnrich zur See
Fähnrich zur See
Junior Midshipman.
          The suffix "(Ing.)" after a rank in place of "zur See" denotes Engineer Officer.  The suffix "der Reserve" denotes a Reserve Officer.  
  (C51296)                                                                                                                              B*2  


  Type VII C.
  Tonnage 500 tons.
  Building Yard Nordsee Werke, Emden.
  Armament Guns.  One quadruple 20-mm. (.79-in.) gun on the lower bandstand, which had been mounted before the last patrol.
    Two twin 20-mm. guns on the upper bandstand, replacing the two single 20-mm. guns carried before the last patrol.
    Two M.G.s, Type 81, on the bridge.
    No heavier armament.
    Torpedoes.  Eleven torpedoes carried on last patrol.  Seven of these were T.5 ("Gnats," electric, acoustic homing anti-escort torpedoes), three were T.3-F.A.T. (electric "Curlies" with magnetic-impact pistol), and the remaining one was a normal T.3 electric torpedo.  The T.5 torpedoes were fitted with Pi. 4 pistols and the T.3 with Pi. 2 pistols.
    N.I.D. Note.  Summaries of information on torpedoes and pistols, obtained from prisoners from various U-Boats, are included in C.B. 04051(76), pages 10 and 11, and C.B. 04051(92), Section VIII.)
    Stowage and loading of torpedoes was as follows:
            Tube I - T.3 "Curly."  Tube II, T.5.
            Tube III - T.5.  Tube IV, T.3 "Curly."
            Tube V - T.5.
            Forward stowage. - Three T.5
                                           One T.3 "Curly."
                                           One T.3.
            After stowage. -      One T.5
  Engines G.W. (Krupp Patent) Diesels with "Büchi" supercharger.
  S.B.T. Fourteen boxes of pills were carried, each box holding six metal containers and each container four pills.  No evidence of the type of pills could be obtained.
  R.D.B. Two boxes of balloons were carried.  No further details of this equipment could be obtained.
  Radar Not fitted.
  G.S.R. Both "Naxos" and "Wanz" sets carried.  (For full description of these sets see Section VIII.)
  W/T Equipment A "Mein" receiver was carried.  The rest of the equipment was Telefunken.  The VH/F set was the new type Lo. 10 U.K. 39. (For particulars of this set see C.B. 04051(92) (U.732).)
    N.I.D. Note.  It is not believed that VH/F Communications are used during operations.)
  Dinghies Thirty one-man dinghies were carried.  One eight-man inflatable dinghy was carried on deck and two four-man dinghies below decks.
  Distiller The fresh water distiller had a capacity of about 10 litres (2.2 gallons) per hour.
  Visual Acuity Pills Black pills were carried, which were issued to the crew to improve their vision at night.
  Badge A round-about.
  Base St. Nazaire.
  Flotilla Sixth.


          "U 340" left St. Nazaire at 1815 on 17th October 1943, escorted by three small minesweepers.  Orders had been received to proceed to Toulon and operate in the Mediterranean, and it was known that four other U-Boats, commanded by Boehme ("U 450"), Brunning ("U 642"), Hornkohl ("U 566"), and Carlsen ("U 732") (see C.B. 04051 (92)) were leaving Brest and La Pallice at about the same time with the same orders.  Prisoners thought that only "U 450" succeeded in forcing the Straits of Gibraltar.  
          Included in "U 340's" complement were 15 new ratings who had been drafted to the boat shortly before sailing.  "U 340" also had a number of dockyard workers on board, who were to take part in practice dives and return to St. Nazaire with the escort.  At 0100 on 18th October, the U-Boat dived for the first time, reaching a depth of 190 metres (623 ft.) and trials were carried out for four hours.  
          Heavy seas made the transfer of the dockyard workers to the escort vessels impossible, and the U-Boat had to turn back to St. Nazaire.  The workers were finally transferred at about 1400 near the harbour entrance, and the U-Boat left immediately without the escort as the route was considered clear.  
          The U-Boat submerged at the 50 fathom line at about 1800 and did not surface again until shortly before dawn the next day.  During the passage to the Gibraltar area, the routine was to submerge at dawn and to remain below the surface for about 14 hours.  They surfaced after nightfall and dived again after about two or three hours, surfacing again about three hours before dawn.  The average depth when submerged was 60 metres (197 ft.).  Surface speed was about 10 knots and submerged speed about 4 knots.  (N.I.D. Note.  More recent prisoners have stated that U-Boats normally proceed submerged at 2-1/2 to 3 knots when on passage through the Bay of Biscay.  This seems more probable than 4 knots.)  
          The course followed was a straight line from St. Nazaire to Cape Finisterre and then due south to a point off the African coast in the latitude of Madeira.  Prisoners were certain that the U-Boat was never nearer than 4 miles from the Spanish and Portuguese west coast.  
          It was the Commanding Officer's policy to avoid action before reaching the Mediterranean, and the time on the surface was cut to the absolute minimum to prevent detection that might disclose that any U-Boats were proceeding towards Gibraltar and the Mediterranean.  Only twice during the passage to the Gibraltar area was the U-Boat compelled to dive as a result of receiving an aircraft contact on the G.S.R.  
          Two of the new-type "Naxos" G.S.R. aerials were carried, but both of these were broken before reaching the Gibraltar area, and "U 340" had to rely on her "Wanz" set, which does not receive contacts on the 8-12 cm. wavelengths for which the "Naxos" is said to be designed.  Some survivors attributed the ultimate loss of the vessel to this mishap.  
          "U 340" proceeded from the African coast on a direct course to Gibraltar.  Night surfacing was reduced even further, seldom exceeding a total of three hours per night.  This part of the passage took four days, and they were attacked by searchlight aircraft on the two nights preceding the passage of the Straits.  
          The first attack took place during the night of 30th/31st October, when a searchlight aircraft dropped three bombs astern of the U-Boat, causing no damage.  The U-Boat crash-dived to 60 metres (197 ft.) immediately.  (N.I.D. Note.  At 2203 on 30th October, Wellington W of 179 Squadron, patrolling off the north-west coast of Spanish Morocco, obtained a Radar contact at a range of 6 miles.  The aircraft turned and homed on to the contact, losing height to 50 ft., and at just under half a mile the Leigh light was switched on, illuminating first the wake and then a fully surfaced U-Boat slightly to port of the aircraft position 35° 33' N., 6° 37' W.  Soon after the Leigh light was switched on the U-Boat opened fire but no tracer was seen only gun flashes.  The aircraft climbed a little and turned to port in an attempt to track over the U-Boat, but owing to the short range this was not possible.  However, the Captain decided to release the depth-charges, thinking that at any rate the U-Boat would be shaken up.  The attack was carried out from Red 80 to the U-Boat's course, releasing from 75 ft. six Mark XI torpex depth-charges, set to shallow depth, spaced 60 ft.  The aircraft turned to port and circled the area, but no further Radar contact was obtained.)  
          The next evening, a signal from another U-Boat was intercepted, stating that the boat was being attacked by aircraft in the Gibraltar area.  It was assumed that this was one of the other four boats attempting to force the Straits, and that she was sunk.  
          Before entering the Straits, the Coxswain told the Commanding Officer that he thought it advisable to retire from the area and recharge the batteries, as they were getting dangerously low.  The Captain would not hear of this proposal, and the Chief E.R.A. is said to have remarked that Klaus intended to scuttle the boat.  
          The second attack took place during the night of 31st October/1st November, when the U-Boat was just west of Tangiers.  "U 340" was proceeding surfaced near some Spanish fishing vessels when a searchlight aircraft attacked, dropping six bombs on the starboard beam, dispersing the fishing boats, and putting "U 340's" starboard main motor out of action, besides causing other damage of a less serious nature.  No G.S.R. warning of the attack had been received.  
  (C51291)                                                                                                                         B**  


          (N.I.D. Note.  Wellington R of 179 Squadron, on patrol in the Straits of Gibraltar, obtained a Radar contact at a range of 2-1/2 miles at 0022 on 1st November.  The Captain realised it would not be possible to carry out the attack immediately, and homed on to the contact, maintaining height at 1,000 ft.  When over the contact, a large wake and object were seen, but it was thought to be larger than a U-Boat.  The Captain decided to investigate, and continued on his course until the contact was 5 miles astern and then turned to starboard, returning on reciprocal.  The Radar contact was regained on the starboard bow at a range of 4-1/2 miles.  The aircraft carried out homing procedure, losing height to 150 ft. and at 1/2 mile the Leigh light was switched on, illuminating a U-Boat fully surfaced in position 35° 50' N., 6° 00' W.  Immediately the Leigh light was switched on, the U-Boat opened heavy and inaccurate flak, tracer passing under the aircraft.  
          The attack was carried out from Green 175 to the U-Boat's course, releasing from 100 ft. six Mark XI torpex depth-charges, set to shallow depth, spaced 66 ft.  Evidence states that the sixth depth charge entered the water just ahead and about Red 5 to the U-Boat's course.  The aircraft then turned to port, but no Radar contact was obtained and nothing was seen when the area around the flame float was illuminated with the Leigh light.)  
          The U-Boat dived immediately to 100 metres (328 ft.), and after about two hours, struck the bottom at about 85 metres (279 ft.).  The crew feared that this might have betrayed their position, but no attack developed.  
          The Commanding Officer then decided that it would be better to drift as far as possible with the current, using the remaining motor at silent speed in order to keep the boat trimmed and under control.  After about two hours, the starboard motor was repaired, the damage proving less serious than was at first feared.  
          At about 0800 on 1st November, the U-Boat was attacked by a surface vessel with two series of depth-charges, but the prompt ejection of S.B.T. pills seemed to mislead the attacking craft and no further attacks developed.  No damage was done to the U-Boat.  
          (N.I.D. Note.  At 0645 on 1st November, H.M.S. "Witherington" obtained a sound contact in position 35° 52' N., 5° 46' W.  H.M. ships "Active" and "Wishart" joined the hunt, during which six depth-charge attacks were made with no apparent result.)  
          An average of 4 knots was made good, and the U-Boat proceeded at a depth of about 80 metres (262 ft.) during the day of 1st November.  About 10 S.B.T. pills were ejected during the passage at various intervals.  
          At about 1800 on 1st November, the U-Boat came to periscope depth.  The Coxswain thought that they were clear of the Straits, but the Commanding Officer, who had no clear idea of his position, doubted this.  He kept coming to periscope depth and looking for enemy ships until 2030, when he surfaced.  A destroyer was sighted in the distance, but the visibility was bad, and "U 340" was not herself sighted.  
          The batteries were by now very low, and the Commanding Officer decided to charge them by proceeding at full speed in a south-westerly direction across a large bay in the Spanish Moroccan coast.  
          "U 340" had been on the surface for about two hours, when destroyers and light surface craft were seen approaching.  These units fired parachute flares which the U-Boat vainly tried to shoot down with her flak armament.  The Commanding Officer of the U-Boat attempted to make his escape by proceeding at full speed on the surface.  
          The boat was pursued by a destroyer, and when this vessel was within range, the U-Boat's Commanding Officer decided to fire his stern torpedo.  However, his nerve failed him at the last moment, and he gave the order to crash dive.  
          (N.I.D. Note.  At about 2240 on 1st November, H.M.S. "Fleetwood," carrying out A/S patrol in company with H.M. ships "Bluebell" and "Poppy" between Cabo Negro and Punta Almina, obtained a suspicious Radar echo at 7,000 yards, bearing 330°.  Echo was held and at 3,000 yards was illuminated with star shell.  Echo was identified as a submarine, conning-tower awash, which dived before guns could be brought to bear.  Echo was lost at 2,000 yards range.)  
          The destroyer immediately attacked with depth-charges which did no damage.  The U-Boat was at 60 metres (197 ft.) when the first charges fell, and the Commanding Officer ordered two S.B.T. pills to be released.  The U-Boat reached bottom at 190 metres (623 ft.), experiencing four further attacks, at each of which S.B.T. pills were released.  Apart from a few broken lamp bulbs, the U-Boat suffered no damage.  
          (N.I.D. Note.  H.M.S. "Fleetwood" carried out four depth-charge attacks between 2254 and 2357 on 1st November, in position 35° 49' N., 5° 14' W., with no positive evidence of destruction.)  
          The U-Boat remained lying on the bottom for about five hours after submerging, and at the end of this time, the supply of air was reduced to a minimum.  The Commanding Officer summoned his officers and men and told them that in view of the impossibility of remaining submerged any longer, and the equal impossibility of surfacing the whole of the next day to re-charge the run-down batteries, he had decided to surface and scuttle the boat, giving the crew a chance to save their lives and swim to the nearby Spanish Moroccan coast.  


          Several survivors expressed to interrogation officers their astonishment at this decision of Klaus.  They said that although they knew the batteries to be run down, the air in the U-Boat had not deteriorated and the boat was perfectly seaworthy.  
          The cumulative effect of the "hunt to exhaustion" had finally told; Klaus was in a very agitated condition, and his fellow-officers apparently had no minds of their own in the matter.  The chief E.R.A. and the coxswain seem to have expressed opinions amounting to mutiny in their disgust at this easy abandonment of the boat, but their fury had no effect on the issue.  
          The tanks were blown about 0430 on 2nd November and the U-Boat, after a moments delay, shot to the surface at a most disconcerting speed, rocking violently and throwing about any members of the crew who were not holding fast.  No attacking vessels were to be seen when they broke surface, and about ten minutes were spent in ranging the crew on the upper deck with their one-man dinghies while final arrangements were made for firing the scuttling charges.  When the order was given to abandon ship the engineer officer and the captain were the last to leave the boat, and shortly afterwards two of the three scuttling charges set exploded.  
          After swimming and paddling for about three hours, the survivors were picked up by some Spanish fishing vessels, which apparently did not make straight for the land, but stood out to sea again.  Shortly afterwards the survivors were taken off, much to their indignation, by H.M.S. "Fleetwood," which closed and stopped the trawlers.  
          (N.I.D. Note.  At 0830 on 2nd November, when H.M.S. "Fleetwood" was sweeping back toward Almina Point, four Spanish fishing vessels were sighted.  On investigation it was seen that a number of seamen, with Mae West life jackets and yellow rubber dinghies, were lying on deck.  Several men were in an exhausted and distressed condition, and it was deemed advisable to transfer them immediately to receive medical attention.  On the advice of the medical officer it was then decided to transfer all survivors in order that they might be given dry clothing and medical assistance.  
  (i)  Additional Fuel in 500-ton VIIC U-Boats  
          VIIC U-Boats are now able to carry an additional 8 m.3 (6.8 tons) of fuel by filling with fuel two of the forward W.R.T. tanks (Torpedozellen 1 and 3) formerly used for washing water.  It is not known when this procedure was initiated, but a general order to this effect has now been issued.  
  (ii)  Extra Look-outs in U-Boats  
          Prisoners from "U 340" confirmed that it has become a general practice to have two extra aircraft look-outs on the bridge.  These men are additional to the normal bridge watch of four, and in "U 340" were stationed on the upper bandstand.  One kept watch from ahead to either beam, and the other from aft to either beam.  
  (iii)  U-Boat with 40-mm. (1.57-in.) Flak Armament  
          One prisoner from "U 340" said that he had seen a 750-ton U-Boat in St. Nazaire with a 40-mm. (1.57-in.) flak gun mounted on the lower bandstand in place of the quadruple 20-mm. (.79-in.) gun now usually carried.  No further confirmation of this mounting has been obtained.  (N.I.D. Note.  37-mm. guns are mounted in U-Boats and it is believed that a new 37-mm. gun is being mounted in some ships.  Nothing is known of a new 40-mm.)  
  (iv)  M.A.N. Engines no longer fitted to U-Boats  
          One "U 340" survivor said that 6-cylinder M.A.N. engines were no longer being fitted to U-Boats.  All the firms making U-Boat Diesel engines are now manufacturing G.W. engines under licence.  
  (v)  K.D.B. Hydrophones no longer fitted to Operational U-Boats  
          A prisoner from "U 135" still under interrogation said that K.D.B. hydrophones are no longer fitted to operational U-Boats, as it is impossible to make the detection units watertight at depths greater than 100 metres (328 ft.).  The prisoner added that the K.D.B. is a much better instrument at short and medium ranges than the G.H.G., and at very short ranges will give a bearing when G.H.G. will not.  However, at long ranges, there is no reception, and the G.H.G. is therefore essential.  
  (vi)  Sonic Telegraphy (German U/T)  
          The same prisoner from "U 135" said that U-Boat under-water telegraphy operates on 788 cycles per second.  (N.I.D. Note.  For previous reference to the use of this equipment, see C.B. 04051 (76), page 10.)  
  (vii)  Method of Firing the 20-mm. (.79-in.) Quadruple Gun  
          The barrels of the 20-mm. quadruple fire in diagonal pairs, each pair being controlled by a foot pedal.  It is the practice to fire only two barrels at a time so that clips of the other pair can be exchanged.  By this means a continuous rate of fire can be maintained.  


  St. Nazaire  
          "U 340" survivors said that when their boat put into St. Nazaire for refitting after the second patrol, they were the 300th boat to be repaired in the yard.  This occasion was made the subject of minor festivities and a propaganda film was made of the boat in dock.  
          They also said that there had recently been a dysentery epidemic in the port, which was attributed to the pollution of the municipal water supply as a result of the destructive R.A.F. raids on the town.  Crews billeted at La Baule are forbidden to use water from the tap except for washing.  The crew of "U 340" had been billeted at the Hermitage in La Baule, and complained of the dull life at the base.  There was practically no entertainment, and the crews remained in La Baule when they were not actually in the U-Boat pens.  
  (i)  Action Tactics  
          "U 340" survivors indicated that apart from intensified efforts to counter Allied Radar detection, and still further reduction in the time spent by U-Boats on the surface, with an increased reluctance to engage attacking aircraft, there have been no major changes in U-Boat tactics.  
          The new "Naxos" G.S.R. receiver enables U-Boats to detect aircraft Radar on wavelengths between 8 and 12 cms., which they were previously unable to do with the "Wanz" type instrument.  "U 340" survivors seemed satisfied that the accounts they had heard of aircraft attacking without any previous warning having been received on the G.S.R. was due to their inability to tune in on the correct wavelength.  
          Aircraft, and particularly searchlight aircraft, are still considered the chief menace to a U-Boat's existence.  Although the policy may have been confined to the five boats proceeding to the Mediterranean at the same time as "U 340," it does not appear from survivors' statements that action with aircraft was to be avoided at all costs.  The reception of a G.S.R. blip was the signal for an immediate crash dive.  
          One or two prisoners stated that on more than one occasion they had seen a red glow from an aircraft some time before the searchlight was switched on.  This was ascribed to some sort of infra-red apparatus which it was supposed the aircraft was using in order to home on to the submarine.  They indicated that look-outs were instructed to look for this red glow as a means of giving the U-Boat's Commanding Officer sufficient warning to crash-dive before the aircraft attacked.  
          (N.I.D. Note.  It is thought that the prisoners may be referring to occasions when they saw an aircraft with a badly-shaped cockpit light.  From our own experience it is known that such a light is visible for a very considerable distance.  It is also known that in spite of flame dampers, exhausts from certain types of aircraft can be seen by U-Boats for some distance.)  
          After a period during which confidence in R.D.B. and S.B.T. seemed to be dwindling, there has been a resurgence in their use, and the Commanding Officer of "U 340" seemed satisfied that the frequent ejection of S.B.T. pills during the passage of the Straits of Gibraltar had certainly misled the attacking destroyers and saved his boat from serious damage.  Frequent use was also made of the decoy balloons, but there was no opportunity to prove their efficacy.  
  (ii)  Navigational Tactics  
          "U 340" survivors indicated that the method of crossing the Bay of Biscay by hugging the Spanish north coast has not become general, and that they had no reason for supposing that the other four boats which left Brest and La Pallice at the same time as themselves followed any other course but their own, straight from the French base across the Bay to Cape Finisterre.  
          The policy of surfacing for the minimum period necessary to recharge the batteries is, however, followed by all boats in the Bay and along the Iberian west coast.  This has the sole purpose of reducing the time during which the U-Boat can be detected by Radar to an absolute minimum.  
          U-Boats remain submerged all day, and surface in the early hours of the morning, submerging before dawn after a further two hours on the surface.  
  (iii)  Passage of the Straits of Gibraltar  
          Nothing in the interrogation of survivors from "U 340" and "U 732" gave reason to suppose that the five U-Boats attempting to force the Straits of Gibraltar had any concerted plan, and there is no doubt that the passage was to have been an individual enterprise on the part of each boat.  
          U-Boat Commanding Officers detailed to take their boats into the Mediterranean are told that it is possible to drift with the current and that the motors need only to be used at silent speed in order to keep the boat trimmed and under control.  
          If the experience of "U 340" can be taken as general practice, it may be assumed that U-Boats effect the passage at a depth of about 80 metres (262 ft.) and make good at an estimated speed of 4 or 5 knots.  The boats remain submerged for 10 to 12 hours before surfacing to plot their position.  U-Boats submerge for the passage in the vicinity of Tangiers.  


  (i)  "Naxos"  
          Most U-Boats leaving French ports are now being fitted with the new "Naxos" G.S.R. set which is said to cover wavelengths between 8-12 cm.  Survivors from "U 340" described the equipment as the simplest yet installed in U-Boats.  It requires no tuning and indicates a contact by a whistling noise in a loud speaker connected to the Radione set in the W/T room.  
          The aerial consists of a brass tube, about 10 in. long and 1-1/2 in. in diameter, at the upper end of which is a mushroom-shaped insulator, probably of semi-transparent material, from which projects a brass spike about 2 in. long.  About half-way down the outside of the tube projects a holder in a wood-covered housing into which fits a detector crystal about 1 cm. cube.  It is apparently held in place by some form of bayonet joint.  About 25 of these detector crystals were carried as spares in "U 340."  
          This brass tube is fixed at an angle of 45°, with the crystal holder on the under side, to a wooden rod about 3 ft. long which is placed upright in two loosely fitting brackets on the forward periscope housing.  The aerial is then above the level of the bridge fairing.  It is rotated in an apparently haphazard fashion by a member of the bridge watch, and is unshipped and stowed in the conning tower when the U-Boat dives.  
          Two wires lead from the crystal and are connected to the "Naxos" set in the control room by means of a metal-screened twin cable.  The set itself is a small metal box about 8 in. cube, which one prisoner described as containing a single valve from which two strongly insulated wires protrude, forming at the same time the support for the valve.  These wires pass through a base board of insulating material, but it is not known what is between the base board and the bottom of the box.  In "U 340" the box was sealed and no member of the crew was allowed to open it.  However, on one occasion the W/T operator, who gave the description of its contents above, took advantage of the absence of the officers to look inside; he then carefully replaced the seals.  Should any fault develop no attempt was to be made to effect any repairs, and a spare set was carried.  
          The set is connected to a power pack and to the pick-up terminals of the Radione set in the W/T room.  Two Telefunken valves have been removed from the Radione set, a first-stage valve Type EF13, and an IF stage valve, Type ECH11.  The set apparently acts as an L.F. amplifier.  
          One W/T operator survivor said that if the Radione set failed for any reason, the "Naxos" set could be connected to the headphone terminals of the "Wanz" G.S.R. set, which would then show a blip on the cathode ray tube, although without any indication of the wavelength.  
          No information could be obtained from survivors as to the effective range of the "Naxos" set.  "U 340" was apparently one of the first boats to be fitted with this gear, and they had little opportunity to test its operational efficiency.  
          Survivors indicated that plenty of these sets were available, and that all boats of the 1st, 6th, 7th and 9th Flotillas were being supplied.  Their most immediate drawback is apparently the fragility of the aerial, which can be broken very easily.  "U 340" carried two complete aerials, and both of these were broken by careless handling before reaching the Gibraltar area.  
          The set was apparently tested by a buzzer worked by a small dry battery which was taken up on the bridge.  "Naxos" was said to be extremely sensitive, and was even adversely affected by an electric hot-air clothes drier when this was switched on.  
  (ii)  "Wanz"  
          "U 340" also carried the older "Wanz" type of receiver in reserve.  The only modification is the morse key built into the anode circuit.  (N.I.D. Note.  This has already been referred to in C.B. 04051(90) ("U 470"), Section V (iii).)  
          It is still feared that British aircraft may be able to home on the radiation which is supposed to emanate from the "Wanz" set, and the operator has instructions never to depress the morse key for more than 10 seconds at a time.  Otherwise the "Wanz" is regarded as the most reliable G.S.R. set yet evolved, although the limitations of its frequency band are admitted.  
          The set is said to contain the following valves:  
                  Ten R.V. 12P. 2,000 (Roehren-Verstaerker 12-volt Heizung Pentode zweitausendfache Verstaerkung = Pentode Amplifier valve with 12 volt on heater and Mu 2,000).  
                  One R.V. 12P. 3,000.  
                  One valve referred to as a "Leistungs R.L. T.5."  
          The only spare parts carried are valves.  There is an order permitting the breaking up of the large Telefunken receiver if additional spares are necessary for the repair of the "Wanz."  
          Orders exist to the effect that if the "Wanz" set finally breaks down, a W/T report must be made to base immediately and it is then left to the Commanding Officer of the U-Boat to decide whether he wishes to continue the patrol or whether he prefers to return to base.  
          One W/T operator survivor stated that the set only fills half the "Wanz" cabinet and that the other half is empty in case it is desired to add any improvements.  


  (i)  German War Casualties  
          "U 340" survivors said that the official figure of 543,000 German war dead is completely disbelieved in Germany, and that the lowest figure generally accepted is 2,000,000.  
  (ii)  W/T Personnel at H-Boat H.Q.  
          A leading telegraphist from "U 340," who had served for a period in the W/T station at U-Boat headquarters at Angers, stated that there were six leading telegraphists and 12 ordinary telegraphists on duty there at a time, assisted by a number of girls.  A six-hour watch was kept during which an average of about 100 messages was picked up.  


          The crew joined "U 340" for "Baubelehrung" in August, 1942, and the boat was commissioned at Nordsee Werke, Emden, on 16th October.  October and November were spent at Rönne for silent running trials.  
          The boat then proceeded to the "Agrufront" at Hel, but in January, "U 340" was rammed by an unspecified U-Boat.  "U 340" proceeded to "Königsberg and remained in dock until March, when the boat returned to Kiel for the first patrol.  
  (i)  First Patrol  
                  C.O.:  Oberleutnant zur See Klaus.  
                  First Lieutenant:   Leutnant zur See Schwarzkopf.  
                  Second Lieutenant:  Leutnant zur See Erben.  
                  Engineer Officer:  Oberleutnant (Ing.) Grether.  
          "U 340" left Kiel about 8th April, refuelling at Kristiansand S. before proceeding north and through the Rosengarten into the North Atlantic.  Only T.1 and T.2 torpedoes, that is to say, normal air and electric torpedoes were carried.  
  While passing through the Rosengarten the boat was attacked by an aircraft, which dropped depth-charges as the U-Boat dived.  They did no damage, and, after a short while, "U 340" came to periscope depth to see if the aircraft was still in the vicinity.  
          The periscope feather must have been sighted by the aircraft, which made another depth-charge attack, causing a minor leak forward as the U-Boat dived again.  The leak was stopped and no serious damage resulted.  
          About two days later, as "U 340" was due to join a group of U-Boats engaged in attacking a convoy (N.I.D. Note.  Possibly S.C. 130), mastheads were sighted on the horizon which were thought to belong to an independent merchantman.  However, the vessel proved to be a corvette, which was joined by an aircraft.   
          A joint depth-charge attack was carried out on the U-Boat, which dived to 100 metres (328 ft.).  However, one depth-charge damaged No. 3 diving tank, and water rushed into the boat aft.  The tank was blown, and the boat, which was becoming stern heavy, brought on an even keel.  No further attack developed, but the U-Boat was obliged to make for Bordeaux, where she arrived after a patrol of thirty-six days.  Nothing had been sunk.  
  (ii)  Second Patrol  
                  C.O.:  Oberleutnant zur See Klaus.  
                  First Lieutenant:   Leutnant zur See Schwarzkopf.  
                  Second Lieutenant:  Leutnant zur See Erben.  
                  Engineer Officer:  Oberleutnant (Ing.) Grether.  
          The only notable event during the second patrol, which lasted sixty days, was the wounding of five members of the bridge personnel, including the Commanding Officer and the First Lieutenant, by splinters which sprayed the bridge when a leading seaman misaimed one of the 20-mm. guns during an air attack.  The only sinking was that of an inflatable rubber dinghy by machine-gun fire after its occupants, five survivors from a crashed Condor aircraft, had been taken on board the U-Boat.  
          "U 340" left Bordeaux about 10th July with orders to operate off the West African coast.  The furthest south reached was 2° N., and the U-Boat patrolled for a time in the vicinity of Freetown.  
          A vessel was sighted at dusk one day, but she showed navigation lights and proved to be a Swiss merchantman, which was allowed to proceed.  While in the Freetown area, a four-engined bomber flew right over the U-Boat without sighting her, and the U-Boat crash-dived in full view of the aircraft.  
          "U 340" was to have been supplied by "U 459" (Korvettenkapitän Wilamowitz-Möllendorf) but a signal was received stating that no supply boat would arrive and ordering "U 340" to return to base.  (N.I.D. Note. "U 459" was sunk on 24th July, 1943, in the Bay of Biscay.)  
          Supplies were very low and the fuel position serious.  As one survivor plaintively remarked.  "We had nothing but Macaroni with dried fruit, and dried fruit with macaroni, and then macaroni with ham, and ham with macaroni."  
          They met another operational U-Boat, which was, however, unable to supply then with any fuel, having only sufficient to return to base herself.  The boats remained within hailing distance for about a quarter of an hour.  Shortly after this meeting, according to one prisoner, on 1st September, 1943, another merchantman, which proved to be a Portuguese vessel, was sighted.  She was stopped, and signalled to produce her papers.  The third officer came aboard the U-Boat, but the papers were in order, and the vessel was allowed to proceed.  The same evening, when the U-Boat was about 200 miles from Cape Finisterre, a series of white, green and red Very lights was sighted ahead.  The Commanding Officer wished to close, but the Engineer Officer endeavoured to dissuade him.  "Sie sind wahnsinnig, das ist bestimmt irgendeine Schweinerei" ("You must be mad; that is some dirty trick or other") was his remark.  However, the U-Boat circled the source of the lights, maintaining a respectful distance, when it was seen that they emanated from a rubber dinghy.  This was found to contain five survivors of a crashed Condor aircraft which had left Bordeaux at 1400 on a meteorological flight.  Two of the motors had gone dead when it was out over the Atlantic.  The sixth man of the crew, the engineer, had been drowned.  The survivors were taken on board and the dinghy sunk by machine-gun fire.  
          As the U-Boat was making Cape Finisterre before entering the Bay of Biscay, she was attacked at night by a searchlight aircraft.  The guns' crews, who had been drafted from the "Admiral Scheer," and seem to have been very inexperienced, jammed the 20-mm. guns on the upper bandstand, and engaged the aircraft with the bridge machine-guns.  One of the leading seamen, apparently wishing to distinguish himself, managed to bring the port 20-mm. gun into action, but in his enthusiasm misaimed the gun and sent a shower of metal splinters over the bridge.  The Commanding Officer, the First Lieutenant, one of the torpedomen who was on the bridge, and two other members of the bridge watch were wounded.  
          As a survivor described the scene, "The whole bridge was spattered with blood," and the resultant confusion was only remedied when the wounded were bundled down the conning-tower hatch and the U-Boat crash-dived.  No bombs were dropped by the aircraft.  
          "U 340" proceeded to St. Nazaire without further incident, where the five wounded men received the "Verwundete Abzeichen" (Wound Badge).  


(i)  Survivors:
English Equivalent.
Klaus, Hans Joachim Oberleutnant zur See Sub-Lieutenant
17.  5.18
Eisenheim, Günter Leutnant zur See Junior Sub-Lieutenant
Erben, Hans-Joachim Leutnant zur See Junior Sub-Lieutenant
26.  7.22
Grether, Hermann Oberleutnant (Ing.) Sub-Lieutenant (E)
13.  2.21
Löcherbach, Paul Obermaschinist Chief Stoker and Chief E.R.A., 1st or 2nd Class.
25.  9.17
Adrian, Hellmuth Obermaschinist Chief Stoker and Chief E.R.A., 1st or 2nd Class.
19.  3.15
Dähler, Kurt Obersteuermann C.P.O. (Navigation)
5.  9.14
Helbig, Kurt Oberbootsmannsmaat Acting P.O. (Seaman's Branch)
5.  5.19
Knoop, Karl-Heinz Bootsmannsmaat Leading Seaman
26.  2.22
Kellermann, Wilhelm Bootsmannsmaat Leading Seaman
Huthuff, Günter Maschinenmaat Leading Stoker and E.R.A., 5th Class
14.  9.20
Hils, Wihelm Maschinenmaat Leading Stoker and E.R.A., 5th Class
Schmitt, Hermann Maschinenmaat Leading Stoker and E.R.A., 5th Class
15.  5.21
Gärtner, Heinz Maschinenmaat Leading Stoker and E.R.A., 5th Class
30.  3.22
Zapf, Karl-Heinz Maschinenmaat Leading Stoker and E.R.A., 5th Class
30.  7.20
Peter, Helmut Funkmaat Leading Telegraphist
3.  8.20
Reiter, Paul Funkmaat Leading Telegraphist
16.  7.20
Hartelt, Helmut Mechanikersmaat L.T.O.
10.  1.21
Riedel, Gotthard Sanitätsmaat Leading S.B.A.
24.  5.21
Patz, Karl Matrosenobergefreiter Able Seaman
29.  9.22
Janszen, Ernst Matrosenobergefreiter Able Seaman
19.  8.23
Hirmke, Freimut Matrosenobergefreiter Able Seaman
3.  7.22
Schafler, Josef Matrosenobergefreiter Able Seaman
22.  2.19
Alfanz, Adolf Matrosenobergefreiter Able Seaman
Philipp, Ernst Matrosenobergefreiter Able Seaman
7.  6.23
Süss, Franz Matrosenobergefreiter Able Seaman
5.  5.24
Kappel, Ludwig Matrosenobergefreiter Able Seaman
8.  5.23
Parczyk, Erich Matrosenobergefreiter Able Seaman
13.  5.23
Kramer, Heinz Maschinenobergefreiter Stoker, 1st Class
16.  4.23
Oster, Helmut Maschinenobergefreiter Stoker, 1st Class
21.  6.24
Mitter, Christian Maschinenobergefreiter Stoker, 1st Class
21.  5.23
Kehnscherfer, Reinhardt Maschinenobergefreiter Stoker, 1st Class
30.  4.23
Niemes, Walter Matrosengefreiter Able Seaman
2.  4.24
Höfer, Willy Matrosengefreiter Able Seaman
7.  5.25
Schekahn, Ernst Matrosengefreiter Able Seaman
9.  9.24
Kuntzsch, Herbert Matrosengefreiter Able Seaman
11.  9.24
Grams, Hermann Matrosengefreiter Able Seaman
17.  8.23
Malcharzik, Walter Matrosengefreiter Able Seaman
12.  1.23
Ehlers, Helmut Matrosengefreiter Able Seaman
29.  9.23
Kallmeyer, Egon Matrosengefreiter Able Seaman
1.  8.23
Kaczmarczyk, Willi Matrosengefreiter Able Seaman
Kellner, Max Matrosengefreiter Able Seaman
19.  1.24
Gutjahr, Walter Funkgefreiter Telegraphist
15.  2.24
De Monte, Stephan Mechanikergefreiter Able Seaman (S.T.)
24.  6.24
Schaa, Hermann Mechanikergefreiter Able Seaman (S.T.)
8.  4.23
Sackler, Sebastian Matrose II Stoker, 2nd Class
Liebehenschel, Rudolf Matrose IV Ordinary Telegraphist
Diezel, Günther Matrose VII (T) Ordinary Seaman Torpedoman
11.  6.23
Officers . .
Chief and Petty Officers . .
Men . .
  (ii)  Casualties - or escaped:  
Heinz Maschinenobergefreiter Stoker, 1st Class
Officers . .
Chief and Petty Officers . .
Men . .
  (iii)  Total Crew:  
Officers . .
Chief and Petty Officers . .
Men . .
(C512296)    500    1/44



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