S E C R E T
 
Op-16-Z
     
     
 
NAVY DEPARTMENT
 
 
OFFICE OF THE CHIEF OF NAVAL OPERATIONS
 
 
WASHINGTON
 
     
     
     
 
Final Report - G/Serial 28
 
     
 
 
REPORT ON THE
 
 
INTERROGATION OF SURVIVORS FROM U-841
 
 
SUNK 17 OCTOBER 1943
 
     
 
AND
 
     
 
U-848 SUNK 5 NOVEMBER 1943
 
     
  Cominch (F-21)  
  Cominch (FX-40) (2)  
  Op-16 via Op-16-1F, Op-16-1  
  Op-16-FA-4  
  Op-16-P  
  BAD (4)  
  DNI (Ottawa) (3)  
  Comnaveu  
  SONRD (2)  
  Ensign Tweedy (CSDIC, ME)  
  Lieut. Hatton (CSDIC, AFHQ)  
  Lt.(jg) Mullen  
  Lt. V. R. Taylor  
  Lt. K. W. Dowie  
  G-2 (Col. Jones)  
  Op-20-G  
  Op-35 (Air Combat)  
  BuShips (Code 815)  
  BuShips (Code 515)  
  BuShips  
  BuOrd  
  Op-30  
     
  12 January 1944  
 
 
 
S E C R E T
 
     

 

     

S E C R E T
 
 
     
     
 
TABLE OF CONTENTS
 
     
 
       
Page
CHAPTER
I.
  INTRODUCTION
1
 
   
 
II.
  DETAILS OF U-841
3
 
   
 
III.
  TORPEDOES
17
 
   
 
IV.
  ELECTRONIC GEAR AND PRODCEURE
26
 
   
 
V.
  GUNS AND GUNNERY
34
 
   
 
VI.
  CREW OF U-841
44
 
   
 
VII.
  EARLY HISTORY OF U-841
48
 
   
 
VIII.
  FIRST AND FINAL PATROL OF U-841
56
 
   
 
IX.
  SINKING OF OF U-841
61
 
   
 
X.
  FINAL REPORT ON U-848
66
 
   
 
XI.
  MISCELLANEOUS REMARKS ABOUT U-BOATS
69
 
   
 
XII.
  BASES
77
 
   
 
XIII.
  OTHER U-BOATS
85
       
 
   
ANNEX
  CREW LIST OF U-841 AND U.S. EQUIVALENTS OF GERMAN NAVAL RANKS
 
     
 
LIST OF ILLUSTRATIONS
 
     
 
                                                                      Facing Page
Plate A Bridge and Platforms U-841
5
 
Plate B R.D.B.
13
 
Plate C Wanz G.1, G.S.R.
26
 
Plate D Combination Radar and G.S.R. Aerial
27
 
Plate E D.F. Gear
28
 
Plate F New type G.S.R.
29
 
Plate G Radar
30
 
Plate H Track Chart U-841
59
 
Plate I Bridge and Platforms U-848
67
 
Plate J Map of Bergen
77
 
Plate K Map of Trondheim
83
 
 
     
 
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CHAPTER I.  INTRODUCTION
 
 
 
 
        This is a joint report on U-841 and U-848.
 
 
 
 
        U-841, commanded by Kapitänleutnant Werner Bender, was sunk by H.M.S. BYARD escorting convoy ONS 20 on the afternoon of 17 October, 1943, in position 59 N - 31 W, some 750 miles East of Cape Farewell.
 
 
 
 
        U-841 was a 750 ton U-boat built at the Deschimag Yards in Bremen.  She had completed her trials at the end of June and was ready to sail on patrol at the time when the U-boat arm was in transition.  Her departure was twice delayed, the first time for a six weeks' return to Bremen, where her second platform was rebuilt and a quadruple mounting 20 mm. added to bring her anti-aircraft armament up to the new standard.  Again in Norway she spent a month awaiting the arrival of the latest search receiver.
 
 
 
 
        The new equipment could not offset the inexperience of her captain to which the older crew members attributed the sinking of U-841 just 13 days after leaving Trondheim on her first and final patrol.
 
 
 
 
        One officer, five P.O.'s and 21 ratings were rescued out of a crew of 54.  Preliminary interrogation of all survivors was conducted at the port of arrival.  Seventeen ratings were brought to an interrogation center in the United States for final questioning.
 
 
 
 
        The crew for the most part had good military bearing and showed evidence of considerable training in security.  The final communicativeness of a number of the men was due to their realization of the hopelessness of the military situation and a growing resentment
 
 
 
 
- 1 -
 
 
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against the Nazi regime for the deception it has practiced on its own supporters.  Some of the more intelligent crew members were willing to go to the limit to help speed the end of the war.
 
 
 
 
        In Chapter X will be found the report on U-848, commanded by Korvettenkapitän Wilhelm Rollmann, sunk 5 November, 1943, in position 10.09 S. - 18.00 W. by 6 U.S. Army and Navy planes based in Ascension Island.  A sole survivor rescued nearly a month later was interrogated in Recife.  In almost uninterrupted delirium he was not able to cast much light on the history of the boat.   Some details were furnished by the crew of U-841 which was built at Deschimag and worked up at Kiel and in the Baltic at approximately the same time as U-848.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
     
     
     
 
 
 
 
 
 
 
 
 
- 2 -
 
 
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CHAPTER II.  DETAILS OF U-841
 
 
 
 
        U-841 was, in general, a standard IX C, 750-ton U-boat.  When no mention is made of any detail of equipment on board it may be assumed to be standard.  The observations below cover a number of points of new or salient interest.  Attention is directed also to Chapter III on Torpedoes, Chapter IV on Electronic Gear and Procedure and Chapter V on Guns and Gunnery.
 
 
 
 
TONNAGE.
 
 
 
 
        750 tons.
 
 
 
 
TYPE.
 
 
 
 
        IX C, Standard
 
 
 
 
BUILDING YARD.
 
 
 
 
        DESCHIMAG, Bremen.
 
 
 
 
FLOTILLA.
 
 
 
 
        2nd Flotilla, Lorient.  Temporarily attached to 13th Flotilla in Trondheim.
 
 
 
 
F.P.N.
 
 
 
        M-49972.
 
 
 
  CALL LETTERS.  
     
          XOE.  
     
  CODE NAME.  
     
          None.  
 
 
 
- 3 -
 
 
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PATRON.
 
 
 
 
        None.
 
 
 
 
INSIGNIA.
 
 
 
 
        None.
 
 
 
 
CAMOUFLAGE.
 
 
 
 
        None.
 
 
 
  PRESSURE HULL CONSTRUCTION.
 
 
     
 
 
        Welded.
 
 
 
 
THICKNESS OF PRESSURE HULL PLATING.
 
 
 
 
        About 25 mm.  amidships, tapering to about 20 mm. at bow and stern.
 
 
 
 
SPACING OF FRAMES.
 
 
 
        About 75 cm. average.
 
 
 
 
SPACING BETWEEN PRESSURE HULL AND UPPER DECK.
 
 
 
          About 20 cm. at conning tower and 1.50 m. at bow and stern.  
     
  DIVING.  
     
          Crash Diving Time:  At Hela U-841 crash dived in 35 seconds.  On patrol she could not do better than 41 seconds due to increased resistance of larger gun platform and of splinter shield on quadruple gun mount.  
     
          Depths dived:  One prisoner claimed U-841 had twice dived to 200 meters, the maximum depth marked on gauges.  This depth was reached  
     
 
- 4 -
 
 
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Click this text to view Plate A  U-841 Bridge and Platforms

     
 
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on last and only patrol and once previously.  At the time of the attack she dived to 120 meters.
 
 
 
 
GUN PLATFORMS
 
 
 
 
        As originally built U-841 had the usual Platform 1 and a small Platform 2.  In Bremen before her first patrol an enlarged Platform 2 was substituted for the original smaller one.  Armored doors between the bridge and Platform 1 were fitted with spring hinges which closed them when a knob on the top of the fairing was struck.
 
 
 
 
        Plate A. shows the final arrangement of the bridge and platforms on U-841.
 
 
 
 
GUNS.
 
 
 
 
        After numerous changes in her armament U-841 finally sailed on her first and final patrol with a 105 mm. on the deck forward, 4 machine guns (MG 15's) on the bridge, two single 20 mm. guns on Platform 1, a shielded quadruple 20 mm. on Platform 2.
 
 
 
 
        A detailed description of the guns' ammunition and gun platforms will be found in Chapter V, Guns and Gunnery.
 
 
 
 
TORPEDOES.
 
 
 
 
        See Chapter III.
 
 
 
 
SCUTTLING CHARGES.
 
 
 
 
        Two types of scuttling charges were carried by U-841.
 
 
 
        The larger ones, known as Sprengtopf A, were pot-shaped, about 6 to 8 inches in diameter and 10 to 12 inches in height.  Only
 
 
 
 
- 5 -
 
 
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two of the larger charges were reported, one being placed in the Control Room on the portside, next to the chart table, one by the D.F. Gear, one over Magazine No. 1.
 
 
 
 
        All charges were reported to be fused with ordinary string type fuses, with 9 minutes burning time.
 
 
 
 
        No charges had apparently been placed in the usual locations next to the torpedoes under the floor plates in the forward and aft torpedo rooms, in the radio room, or in the conning tower.  The reason given was that at the start of a patrol the boat is too crowded with stores to permit the placing of scuttling charges.
 
 
 
 
        Only one fuse was actually lit at the time of the sinking and that was extinguished by the Engineer Officer on orders of the Captain, when it was evident that the boat was sinking rapidly.
 
 
 
 
S.B.T.
 
 
 
 
      Fitted in after head.  Apparently only chemical projectiles were carried.  A number of projectiles were reported fired at the time of the sinking.
 
 
 
 
D.C.P.
 
 
 
 
        Not Fitted.
 
 
 
 
RUBBER COVERING.
 
 
 
 
        Never used on U-841.
 
 
 
 
ENGINES.
 
 
 
        Two M.A.N., 9 cylinder Diesels of 2050 H.P. each, 4 cycle, single acting.
 
 
 
 
        Bore:  400 mm.
 
 
 
 
- 6 -
 
 
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        Diameter of pistons:  399.70 mm.
 
 
 
 
        Stroke:  460 mm.
 
 
 
 
        Rotation:  Starboard, clockwise, forward.
 
 
                       Port, counterclockwise, forward.
 
 
 
 
        Engine Numbers:  Starboard 730 - 740
 
 
                                    Port         730 - 750.
 
 
 
 
        Nicknames of engines were "Hein" and "Fitsche" - Hamburg comedians.
 
 
 
 
        The pistons in the M.A.N. engines were made of light alloys, two-thirds lighter than gray iron.  Piston heads were oil cooled.  Wrist pins were rigidly mounted in steel bushings hot pressed into pistons.  Connecting rods and crankshafts were forged.  Bearings were babbit.  Cylinder heads were gray iron.  The upper half of the connecting rod bearings were bronze; the lower half was babbit.
 
 
 
 
        The capacity of the reciprocating cooling water pumps was 92 cubic meters per hour for each pump.
 
 
 
 
        The M.A.N. vibration dampers on forward end of crankshafts each contained 14 springs.
 
 
 
 
        The reversing gear longitudinally displaced the camshaft 38 mm and required 70 atmospheres of pressure and 4 to 5 seconds for operation.  Each flask in the reversing gear contained 4 liters of oil.
 
 
 
SUPERCHARGERS.
 
 
 
 
        A supercharger drive of a new type was fitted.  In place of the conventional large ring gear on the camshaft directly driving a
 
 
 
 
- 7 -
 
 
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small pinion on the impeller shaft, a pinion on the crankshaft drove a ring gear on a countershaft, on which was mounted a hydraulically controlled conical friction clutch and vibration damper unit similar to that on the crankshaft.  It consisted of two main parts, essentially discs, one of which was keyed or otherwise fastened to the countershaft and which could be considered as the hub of the unit.  Four radial members extended outward.  The other part was free to revolve upon the shaft; it could be considered as the felloe of the unit.  Four radial members projected inward between the members of the hub part.  Eight compression springs were placed between the members, held in place by cups and bolts.  Guides and retainers made up the remainder of the unit.  The remainder of the drive consisted of other gearing of conventional design.  Gears were cut from Krupp V2a steel, stated to be hard and non-corrosive by sea water.
 
 
 
 
        The blower itself was of the simple centrifugal type, with vanes about 2.0 to 2.5 cm. wide and an impeller diameter of 1.30 meters, turning at 1500 R.P.M., with a crankshaft speed of 480 to 500 R.P.M., at which speed the pressure was stated to be 0.2 atmosphere (2.94 P.S.I.).
 
 
 
 
        The drive and blower were said to be noiseless in operation and that the 11-1/4 degree play between the parts of the damper prevented the stripping of gears.  A further preventive was the calculated slipping of the clutch when first engaged.  The drive was also said to be similar to that of the Kaspelgebläse (Root's type).  The entire unit was of M.A.N. manufacture.
 
 
 
 
- 8 -
 
 
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MAIN CLUTCHES.
 
 
 
 
        The main clutches were of the conical friction type, made by BAMAG.  They were lined.  They were designed to slip until the last moment when a spring actuated stud made positive contact.
 
 
 
 
ENGINE SPEED TABLE.
 
 
 
 
Telegraph Speeds Surface Speed
   
K.F. (Dead Slow) 10 knots
   
L.F. (Slow) 12 knots - without supercharging
   
H.F. (Half Speed) 14 knots
   
2x H.F. (3/5 Speed) (seldom used)
   
G.F. (3/4 Speed) 16  knots
   
2x G.F. (Full Speed) (Seldom used) - with supercharging
   
A.K. (Flank Speed) 18 knots, possible 20
 
 
 
 
        Critical speed of engines:  190 R.P.M.
 
 
 
 
        If motors/generators were operated in tandem with Diesels at A.K. speed would be 22 knots, but this procedure was never used on U-841.
 
 
 
 
NOTES ON FUEL CONSUMPTION.  (Taken verbatim from notebook of Chief Warrant Machinist)
 
 
 
 
        (O.N.I. Note:  No attempt has been made to reconcile the discrepancies.)
 
 
 
 
                Consumption at 460 R.P.M.  A.K.
 
 
 
 
                        100 liters in 4 minutes
 
 
                        300 liters in 19 minutes
 
 
                        500 liters in 35.5 minutes
 
                        656 liters in 8 hours
 
 
 
 
- 9 -
 
 
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                Hourly consumption at A.K. - 410 liters.
 
 
 
 
                        Port                - 392 liters per hour
 
 
                        Starboard       - 424    "     "      "
 
 
 
 
                Port 462.1 R.P.M. 392 liters per hour
      329 kg.     "      "
       
  Starboard 463.7 R.P.M. 424 liters   "      "
      356 kg.     "      "
       
  Port 406 R.P.M. 262 liters per hour
      220 kg.     "      "
       
  Starboard 409 R.P.M. 280 liters   "      "
      235 kg.     "      "
       
  Both engines 320 R.P.M. 252 liters   "      "
       
  Both engines 240 R.P.M. 149 liters   "      "
 
 
 
 
NOTES ON TANK CAPACITIES OR CONTENT.  (Taken verbatim from notebook of Chief Warrant Machinist.)
 
 
 
 
Tank
Contents or Capacity
cubic meters (?)
   
Diving Tank 2 17.80 Port
  17.80 Starboard
   
Diving Tank 3 25.80 Port
  25.80 Starboard
   
Diving Tank 4 32.66 Port
  32.66 Starboard
   
Diving Tank 6 34.26 Port
  34.26 Starboard
   
Diving Tank 7 32.60 Port
  32.60 Starboard
  _____
  286.24 (243.30 T.)
 
 
 
 
        (O.N.I. Note:  Apparently these figures are contents of, or capacity of, tanks used for fuel oil, as they are immediately followed by
 
 
 
 
- 10 -
 
 
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meter readings on tanker barge and aboard.)
 
 
 
 
Sump Port 400 liters  
     
Sump Starboard 400 liters  
     
Port-aft   9.7 cubic meters
     
Port-forward   8.7    "        "
     
Starboard-aft   8.4    "        "
     
Starboard-forward   7.3    "        "
 
 
 
 
LUBRICATING OIL SUPPLY.
 
 
 
 
        1 April, 1943 - 6849 liters.
 
 
 
 
        Additional contents or capacities:
 
 
 
 
                  O.N.I. Comments
     
  46.74 Quick diving tank (?)
     
  5.36 (?)
     
  20.00 Diving tank 2 (?)
     
  25.80 Diving tank 3 port or starboard
     
  32.66   "         "     4   "    "        "
     
  34.26   "         "     6   "    "        "
     
  32.60   "         "     7    "    "        "
  ____  
  197.42 Apparently total capacity, in cubic meters, tanks on one side
 
 
 
 
BATTERIES.
 
 
 
 
        Usual lead-acid type, hard rubber cases, no inner flexible lining.
 
 
 
 
        Eleven of 20 cells checked after depth charging were ruptured.
 
 
 
 
- 11 -
 
 
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MOTORS/GENERATORS.
 
 
 
 
        2 units of 500 H.P. each.
 
 
 
 
PUMPS.
 
 
 
 
        1 main ballast, double impeller, could be used at single stage or in series.
 
 
 
 
        1 auxiliary ballast, reciprocating.
 
 
 
 
PERISCOPES.
 
 
 
 
        1 observation.
 
 
 
 
        1 attack.
 
 
 
 
COMPRESSORS.
 
 
 
 
        1 electric.
 
 
 
 
        1 junkers crankless Diesel.
 
 
 
        The junkers crankless Diesel compressor operated at a constant speed of 180 to 200 strokes per minute.  The pressure of the stages  was as follows:
 
 
 
 
1st stage     4.5 Kg. per Sq. Cm.
   
2nd stage   25.0   "      "     "      "
   
3rd stage   45.0   "      "     "      "
   
4th stage 205.0   "      "     "      "
 
 
 
          A pressure retainer valve was on the discharge side of the 4th stage.  It was set for 205 Kg. per sq. cm.  Until this pressure had been built up, no air passed into the discharge line and into the flasks.  This device regulated operations at a constant speed regardless of pressure in air flasks.  An automatic cut-off  
     
 
- 12 -
 
 
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Click this text to view Plate B   Radar Decoy Balloons

     
 
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was also installed, and operated when pressure exceeded the setting.
 
 
 
 
        In starting the compressor, starting air was admitted into several stages, particularly the second, to equalize pressures and thus prevent a piston from going through a head.  A soft copper stud on the inner surface of a head was an added protection for several unequalized starts, until it had been flattened against the head.
 
 
 
 
COMPRESSED AIR SUPPLY.
 
 
 
 
        8 groups of 8 flasks each.
 
 
 
 
OXYGEN SUPPLY.
 
 
 
 
        Oxygen was carried in liquid state and fed into circulating blower system through a simple pressure reduction valve.
 
 
 
 
RUDDER CONTROLS.
 
 
 
 
        Electric remote and emergency hand controls.  Remote control station on bridge was in pressure proof container.
 
 
 
 
GERMAN ASDIC.
 
 
 
 
        Not fitted.
 
 
 
 
RADAR.
 
 
 
        Fitted.  (See Chapter IV)
 
 
 
 
R.D.B.
 
 
 
          Carried.  See Plate B.  
     
         The type of R.D.B. carried on U-841 is shown in figure 1.   
     
          4 hydrogen flasks were carried in 2 pressure proof containers in the conning tower fairing between Platforms 1 and 2.  (No. 15 on Plate A, facing p. 5.)  
     
 
- 13 -
 
 
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        It was stated that the box in which balloon was kept acted as the anchor.
 
 
 
 
        The types shown in figures 2 and 3 were not carried by U-841 but were observed by a member of the crew during trials in Kiel.
 
 
 
 
G.S.R.
 
 
 
 
        Fitted.  Wanz G.1 installed just before U-841 left on patrol.  Both Runddipol and radar aerial used.  (See Chapter IV.)
 
 
 
 
D.F. GEAR.
 
 
 
 
        Fitted.  Loop aerial (No. 1 on Plate A), retractable into the forward portside fairing of the bridge, was connected to long wave receiver.
 
 
 
 
COMMUNICATIONS.
 
 
 
 
        (For detailed account see Chapter IV.)
 
 
 
 
        Transmitters.
 
 
 
 
        1.  200 W. Telefunken short wave.
 
 
 
 
        2.  40-70 W. Station Lorenz short wave.
 
 
 
        3.  Telefunken long wave.
 
 
 
 
        Receivers.
 
 
 
          1.  Telefunken - all wave.  
     
          2.  "Main" short wave receiver installed shortly before sailing, replacing previous 5 tube, 6 stage receiver.    Very high frequency Walkie Talkie set (Tornnister Gerät) was used only during Tactical Exercises in Baltic.  
     
 
- 14 -
 
 
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HYDROPHONES.
 
 
 
 
        G.H.G.  Fitted.
 
 
 
 
        K.D.B.  Not fitted.
 
 
 
 
ECHO SOUNDER.
 
 
 
 
        "Atlaslot" fitted
 
 
 
 
ELEKTROLOT.
 
 
 
 
        Fitted.
 
 
 
 
GYROS.
 
 
 
 
        Anschütz.  1 Master, 4 repeaters, one of which was in pressure proof container on bridge.
 
 
 
 
DEPTH GAUGES.
 
 
 
 
        Gauges registering to 200 meters in the Control Room, Forward and Aft Torpedo Compartments.  Gauge registering to 25 meters in the Control Room.  Depths over 200 meters had to be taken from the water pressure gauge in the Control Room which will give readings to 30 Kilos per sq. cm.  The equivalent of about 300 meters depth.
 
 
 
OIL TESTING APPARATUS.
 
 
 
 
        The "Jentzche Gerät" in U-841 was an apparatus used for determining such as flash point, viscosity, etc.
 
 
 
          The "Ortel and Pflug" was another piece of apparatus used for determining the water content of oil.  Powdered magnesium was used for this purpose.  
     
 
- 15 -
 
 
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RUBBER BOAT.
 
 
 
 
        Carried.  Not used at sinking.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
- 16 -
 
 
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CHAPTER III.  TORPEDOES
 
 
 
 
TORPEDOES.
 
 
 
 
        According to statements of torpedo-room personnel, U-841 carried 14 torpedoes, of which 6 were air-drived FAT's (FAT-1) and 8 were electric torpedoes with impact-magnetic firing (T-3).  Stowage of these torpedoes was as follows:
 
 
 
 
        In forward torpedo compartment:
 
 
 
 
                Tube 1:  T-3
 
 
 
 
                Tube 2:  T-3
 
 
 
 
                Tube 3:  FAT-1
 
 
 
 
                Tube 4:  T-3
 
 
 
 
                Under floor-plates:  one T-3 and three FAT-1
 
 
 
 
                On floor-plates:  two T-3.
 
 
 
 
        In stern compartment:
 
 
 
                Tube 5:  T-3
 
 
 
 
                Tube 6:  FAT-1
 
 
 
                  On floor plates:  one T-3 and one FAT-1.  
     
         (No mines were carried at any time.)  
     
          All of U-841's torpedoes could be set to run at depths of 0 to 12 meters.  (Prisoners had heard that a newer setting-gear allows depths 0 to 15 meters.)  
     
          The air-driven FAT's had two to six-bladed propellers, and the electrically-driven had two-bladed propellers.  
     
 
- 17 -
 
 
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        The air-driven FAT's were fitted with impact firing pistols (AZ) only.  The electric torpedoes were provided with MZ/AZ pistols, i.e., combination magnetic and impact firing.  One spare MZ/AZ pistol was carried.
 
 
 
 
        No torpedoes were carried in upper-deck containers, these having been removed during final overhaul in Stettin.
 
 
 
 
        No acoustic torpedoes were carried, nor any of the circling torpedoes (Kreisläufer or Kreisaale) reported recently on other U-boats.  It is interesting to note that torpedo-room personnel under interrogation claimed to have received no instruction of any sort on acoustic torpedoes; one, in fact, stated that he had never even heard of any except English ones.
 
 
 
 
        Prisoners had likewise never taken any course of instruction in FATs and had only vague knowledge of details of course, length of run, mechanism, etc.
 
 
 
 
        Prisoners were familiar with the following terms and their meaning as indicated:
 
 
 
 
                T-1:  air driven torpedo.  Ato.  G7a.
 
 
 
 
                T-2:  electric torpedo.  Eto.  G7e.
 
 
 
 
                T-3:  electric with combination magnetic and impact firing.  Et0 with MZ/AZ.
 
 
 
 
                FAT-1:  air driven FAT.  Ato FAT.
 
 
 
 
        T-4, T-5, FAT-2, FAT-x were unknown to prisoners,
 
 
 
 
- 18 -
 
 
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as were the terms Pi-1 to Pi-5.  Pistols were referred to and described as follows:
 
 
 
 
PiG7h: Impact firing (AZ).  Short pistol with four whiskers
   
MZ/AZ Combination impact and magnetic firing.  Long pistol with four whiskers.  A torpedo with magnetic firing is set for a depth of two meters greater than the draught of the target ship; it detonates under the ship, exerting explosive force upwards.
   
Arming distance for both pistols was given as 300 meters.  It was stated that neither pistol could be used in a sea force greater than 5.  Electric torpedoes had one speed, 30 knots.
 
 
 
 
        The FAT's were all set for a speed of 30 knots, though the other two usual settings of 40 and 44 knots were not blocked off.
 
 
 
 
        The rudder-lock setting (Rudersperrung) in operation as the torpedo leaves the tube was stated to be 30 for air torpedoes and 40 for electric (see Final Report U-664, G/serial 27, pages 56-58).
 
 
 
 
        The usual procedure of servicing electric torpedoes (airing daily, filling and charging every four or five days) was followed on board U-841.  One prisoner
 
 
 
 
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volunteered the information that the electric torpedo has two batteries of 28 cells each.  The life of these batteries was said to be two years.
 
 
 
 
        U-841 fired no torpedoes during her sole war patrol.
 
 
 
 
Additional Torpedo Information.
 
 
 
 
        The coxswain of U-841, who had attended Torpedo Fire Control School in Flensburg from 9 May 1943 to 12 June 1943, proved to be an unexpected source of further information on torpedoes.  While most of his instruction was concerned solely with computation of firing data (it is emphasized that he is not a torpedoman), the following newer torpedo types were more or less completely explained to him in Flensburg.
 
 
 
 
        Anti-destroyer Circling Torpedo  (O.N.I. Note:  This torpedo was called FAT-2 by the prisoner.  Although the description does not agree with that given under FAT-2 in Final Report U-664 G/serial 27, pages 51 and 52, it must not be assumed that the following is necessarily inaccurate.  Reports from other sources confirm the use of the term to describe a circling torpedo steered by FAT apparatus.  In certain details, however, inaccuracies may occur.)
 
 
 
 
                Propulsion:  Air-driven.
 
 
 
 
                Depth setting:  Same as in other torpedoes.
 
 
 
 
                Arming run:  150 meters.
 
 
 
 
- 20 -
 
 
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                Speed:  30 or 40 knots, probably always set at 40 knots.
 
 
 
 
                Stowage:  Can be shot from bow tubes or from stern tube(s).
 
 
 
 
                Pistol:  Impact.
 
 
 
 
                Maximum run:  Same as for ordinary air torpedo.
 
 
 
 
                Description of run:  The initial straight run is set to coincide with distance to target.  On reaching the end of the initial straight run, the torpedo turns left and describes a circle with a constant radius.  It will continue to describe this circle until it hits the target or is exhausted.  The diameter of the circle is pre-set and bears some relation to the length of the target, the smaller the target, the smaller the diameter of the circle).
 
 
 
 
                                                             
 
 
 
 
        The torpedo always turns left, and the circle remains on the same spot.
 
 
 
 
        Setting gear:  Although this torpedo differs radically from FAT-1, the same setting spindle (see Final
 
 
 
 
- 21 -
 
 
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  Report U-664, G/serial 27, page 52) is used.  It is always set on "Short Leg" (Schleife kurz).  Prisoner stated that, since the torpedo always turns left, it makes no difference whether Short Leg Right or Short Leg left is set.  
     
 
        Steering:  The prisoner stated there was no acoustic mechanism and no magnetic mechanism in this torpedo.  FAT settings alone control path of torpedo.
 
 
 
 
        Effectiveness:  The prisoner was never on a boat carrying this type of torpedo and has no first-hand knowledge of its use and effectiveness.
 
 
 
 
        Tactics:  This torpedo is primarily a defense weapon to be used against escort vessels ("Zerstorer-Abwehr-Torpedo").  When the U-boat realizes that it has been detected or sighted by the escort vessel, whatever the relative bearings, the U-boat will turn away and try to put the escort vessel astern, bearing roughly 180 degrees relative, target angle as near zero degrees as possible (prisoner said that ten degrees variation on either side of these bearings would not affect chances of a successful shot, but greater variation probably would).  (NOTE:  Torpedo can be fired when target bears zero degrees or 180 degrees from U-boat and U-boat bears zero degrees or 180 degrees relative from the target, ten degrees variation on either said causing no lessening of the effectiveness of the shot.)
 
 
 
 
        Distance to the target is estimated and the initial straight run set to correspond with this distance.
 
 
 
 
- 22 -
 
 
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  Length of target is estimated and diameter of circle determined.  The torpedo is fired (in above case from stern tube), passes target's port side, circles round target's stern and hits on the target's starboard side.  Whatever evasive movement the target vessel may attempt, it will be trapped within the circle and eventually hit on starboard side, usually amidships.  
     
 
        The prisoner definitely stated that any ship moving at speeds 5 to 38 knots would certainly be trapped.  At speed less than 5 knots, the target would remain within the circle unharmed;  at a speed greater than 38 knots the target could escape from the circle.
 
 
 
 
        Prisoner had no exact knowledge as to whether this torpedo would be slightly angled so as to put the target in the exact center of the circle, but admitted that this was possibly the case.
 
 
 
 
         Firing Data and settings:
 
 
 
 
                1.  Torpedo depth setting and torpedo speed.
 
 
 
 
                2.  Speed of target.
 
 
 
 
                3.  Distance to target and initial straight run.
 
 
 
                4.  Length of target.
 
 
 
        Miscellaneous:  Prisoner does not know how long the circling torpedo has been in use.  He never heard of the circling torpedo being fired in spread, nor does he now of the term FAT-x.
 
 
 
 
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          Falcon (Falkentorpedo):  Prisoner received no instruction in this torpedo.  It was mentioned by one of his teachers (a warrant officer) who had been present at experiments on this torpedo.  The only facts that can be established are as follows:  
     
 
                Speed:  20 knots, electrically driven.
 
 
 
 
                Tactics:  Shot at a departing target, target angle being 180 degrees.  Used against merchant vessels, not against escort vessels.  Can be fired from bow or stern tubes.  Hits target in stern.
 
 
 
 
                Path of Torpedo:  A straight run, then zig-zags thus:
 
 
 
 
                                                                   
 
 
 
 
                Prisoner did not know whether this torpedo has or has not acoustic or magnetic apparatus.  The torpedo was not in operational use, June 1943.
 
 
 
 
        REG or RECK (?):  Stated to be the cover-name of a new torpedo that describes "peculiar convolutions."  It is not yet operational.
 
 
 
        TORPEDO COMPUTER.
 
 
 
        A coxswain stated that all boats have recently been equipped with a new torpedo computer (Vorhaltrechner) with an extra switch was not on the older type carried
 
 
 
 
- 24 -
 
 
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  by the prisoner's previous boats.  This is an angle impact switch (Endlagenschalter).  The switch operates a light which goes on when the torpedo's hitting angle in side of ship would be greater than 90 degrees.  The light goes on automatically when the relative position of the U-boat and the target is such that the above would result.  When the light goes on, it gives warning that the calculations have ceased (they are automatically blocked off) the the data must be reset.  This device is solely for maneuvering; i.e., when the U-boat is definitely on favorable firing course the switch would not be operative.  Its purpose is to eliminate errors formerly made in keeping running data during maneuvering.  
     
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
- 25 -
 
 
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Click this text to view Plate C   Wanz G.1 G.S.R.

     
 
S E C R E T
 
   
 
CHAPTER IV.  NEW ELECTRONIC GEAR AND PROCEDURES
 
     
 
WANZ G.1 G.S.R.
 
 
 
 
        U-841 was said to be the second U-boat fitted with Wanz G.1 G.S.R. also said to be known under the name of Hagenuck.  The installation was made in Trondheim.  So much importance was attached to the apparatus that U-841 postponed her sailing at least three weeks awaiting its arrival.
 
 
 
 
Attached Plate C illustrates the Wanz G.1 (prisoner believes this means Wellenanzeigerät No. 1).  The apparatus is fitted with a cathode ray tube graduated for wavelength from 120 to 180 cm.  On this cathode ray tube a green trace appears when in operation.  The trace has a pulse of 25 to the second, operated by a motor-driven automatic scanner.  Operation is as follows:  
 
 
 
 
 
        1.  Set is switched on.
 
 
 
 
        2.  Knob is turned to automatic scanning (4 on sketch).
 
 
 
 
        3.  The button (2 on sketch) revolves and the trace then travels on the tube.
 
 
 
        4.  When a blip appears on the screen the knob is turned to hand tuning (5 on sketch).
 
 
 
        5.  Operator puts on head-phones and used the button (2 on sketch) for fine tuning.
 
 
 
 
        6.  If a bearing is desired, this can be obtained by plugging into the antenna socket (3 on sketch) a plug connected to the radar aerial which is rotated until a
 
 
 
 
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Click this text to view Plate D   Combination Radar and G.S.R. Antenna.

     
 
S E C R E T
 
   
  bearing is obtained.  The set is normally connected to the basket type aerial which, on U-841, was identical to that on U-664.  
     
 
        On U-841 the Wanz had been to some extent re-wired and a telegraph key fitted to the upper earphone connection.  With this key connected in the circuit the tube heater could be turned on independently while the set would not actually operate unless the telegraph key were pressed.  Prisoners stated that it was a policy to press this key and therefore operate the set for only 10 seconds out of every minute.  Prisoners believed that continuous use of the set would have set up radiations which could have been D/F'd by the enemy.
 
 
 
 
        The G.S.R. was fitted with the conventional fixed basket type antenna, the radar antenna being used as described above when a bearing was wanted.
 
 
 
 
COMBINED RADAR AND G.S.R. ANTENNA.
 
 
 
 
        Plate D gives full details of the combined radar and G.S.R. antenna, which was mounted on U-841.  The antenna was encased in a recess on the port side of the conning tower fairing (No. 9 on Plate A).  When in use it was elevated on a central shaft by compressed air to a height of 1 meter to 1.5 meters (approximately 3 to 5 feet) above the fairing.  The shaft and leads entered the pressure hull through the water-tight glands.  The antenna was rotatable in 3600 by means of a hand wheel located in the control room, where the radar set was also kept.  If it was desired to use this antenna
 
 
 
 
- 27 -
 
 
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Click this text to view Plate E   D/F Gear

     
 
S E C R E T
 
   
  with the Wanz G.S.R., the lead was carried directly to this set, and a second operator rotated the aerial to get a bearing.  It was positively stated that the reflectors on Plate D, rear view, had no electrical leads to them of any kind, and served purely as additional reflectors even though they were behind the main mattress, illustrated on Plate D, front view.  Prisoner claims that for radar this antenna was accurate within 10 or 20; when used with the G.S.R., he states that faint signals could be received up to 150 to each side of the actual bearing.  For G.S.R., he thought the bearing would be accurate within 50, but this is only an estimate as the prisoner had only a very limited experience in its use.  The rear side of the antenna is never rotated toward the target.  
     
 
D.F. GEAR.
 
 
 
 
        Plate E shows the arrangement of dials on the D/F gear.  The circular antenna was retractable into the forward starboard side of the bridge fairing.  Signals on LF (Langwellen) 250-2500 meters and VL/F (Längstwellen) 10,000 meters and up were received.
 
 
 
 
        Radiomen from U-841 supplementing and confirming statements made by radiomen from U-664 gave the following outline of procedure for the sending of homing signals by a contact keeper:
 
 
 
 
        Such homing signals are given on long wave - it was said between 500 and 1000 meters.
 
 
 
 
        When a U-boat sights a convoy she reports to control, who then instructs her to transfer to the convoy wavelength (Geleitzugschaltung).  The contact keeper must then issue a signal,
 
 
 
 
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S E C R E T
 
     

Click this text to view Plate F   New G.S.R.  Naxos

     
 
S E C R E T
 
   
  consisting of Beta Beta, followed by the number of the operational square in which he is and the signature, repeated within an hour.  If a contact keeper has made no such signal after an elapsed time of one and a half hours, control will appoint another boat to become contact keeper for the convoy.  The frequencies to be used as looked up in a book which covers all dates for a period of two months.  Frequency changes 8 times a day.   
     
 
        Should one of the boats that is attempting to join the contact keeper request a beacon signal, control will instruct the contact keeper to make this signal.  This consists of a VVV, or a similar group like RRR, followed by the signature transmitted very slowly.  Intervals of repetition of the beacon signal are determined by the date and the time of day and are set out in the same book in which the convoy frequencies, above mentioned, are listed.
 
 
 
 
NEW TYPE G.S.R.
 
 
 
 
        Two radiomen from U-841, when at the G.S.R. school at Le Touqet in early August 1943, were shown a small and very primitive G.S.R. set which was apparently at the time used only for demonstration purposes.  Plate F shows this set.  Prisoners were positive that there were no dials of any kind on the box, but are quite definite that the antenna is exactly as shown.  The insulation (at 5 on the plate) was said to be of plexiglass and they stated that they had noticed that the dipole inside the plexiglass was reduced to almost half its diameter, i.e., to about 4 mm.  Prisoners are not clear about the purposes of the slotted rubber disc, illustrated at 2 on the plate.
 
 
 
 
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Click this text to view Plate G   Radar

     
 
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  They were told that U-boats were to be equipped with G.S.R. having the same characteristics as this set, i.e., to cover wavelengths in the vicinity of 8 cm.  
     
 
(O.N.I. Note:  The equipment here described is evidently the Naxos G.S.R. subsequently reported in operational use on U-boats.)
 
 
 
 
RADAR.
 
 
 
 
        Plate G illustrates the three units of radar apparatus carried on U-841.  A prisoner from this boat, with a limited knowledge of the subject, gave the following directions for use of radar and its operation:
 
 
 
 
        Current is supplied by a 6 KVA transformer.  After the 6 KVA transformer had been turned on, the main switch on the radar is turned to "on".  After a pause of two minutes (for pre-heating the apparatus, otherwise there is danger of overload), the high voltage is adjusted by means of the high voltage regulator up to the red mark which is indicated on the scale.  The X-apparatus is next carefully adjusted, that is, the two amplitudes which the tube shows must be turned on full.  Then the constant amplitude of the main radar apparatus is in turn regulated with the help of the adjusting knob.
 
 
 
 
        When in operation, the cathode tube gives a horizontal and vertical base.  The horizontal base runs across the entire surface of the tube-screen, while the vertical base takes in only the upper diametrical half.  The constant amplitude comprises three-quarters of the height of the vertical base, and
 
 
 
 
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  has a width of about twelve mm.  It is called constant amplitude because it retains its height and width during the entire time the radar is in operation.  For the purpose of better observation only, the field may be increased by shifting the constant amplitude to the left, but even then the constant amplitude retains its height and width unchanged.  Shifting is accomplished  by means of a distance indicator.  The ratio of displacement is 1:20, and is marked by the right scale for 10, 100, to 1000 meters, and by the left scale for 1000 to 20,000 meters.  
     
 
        Besides the constant amplitude and the base, the cathode tube also shows tube disturbances.  These are called "grass".  Tube disturbances jump up steeply and fall back in narrow, rounded-off curves on the screen.  Because these impulses cover 890, a strong illumination is produced on the screen, and thus every indication of direction can be recognized immediately with great certainty.
 
 
 
 
        The apparatus has a high voltage of 15,000 volts.  The plate current has about 5,000 to 6,000 volts.
 
 
 
 
        The radar has, among other tubes, RV12P2000, RV12P2001, AD101, RS291, in considerable number.
 
 
 
 
        The radar carried by U-841 was designed for use exclusively against surface craft.  It was not intended for use against aircraft and had no elevation indicator.  Actually U-841 had never made any operational use whatever of its radar as her
 
 
 
 
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  captain shared the belief common to most German U-boat commanders that we have search gear that can instantly D.F. their radar transmissions.  
     
 
COVER NUMBERS FOR U-BOATS IN BALTIC.
 
 
 
 
        A radioman from U-841 states that the cover numbers for U-boats on trials in the Baltic for communication purposes are always the U-boat's number plus 600.  So for example, the cover number which control used to call U-841 all through her trials was 1441.  (O.N.I. Note:  While this prisoner has stated that this is a standard practice it should be borne in mind that his experience in this respect is limited to the trials of U-841 alone, which took place from February to May 1943.
 
 
 
 
GOLIATH TRANSMITTER.
 
 
 
 
        Radiomen from U-664 and U-841 state that since the construction of the new 1,000 K.W. "GOLIATH" transmitter known to them as "Paris I", and which operates on extremely long wave, around 15,000 meters, it is possible for U-boats to receive transmissions on such wave lengths when submerged to a depth up to 30 meters, under favorable conditions.  Before the construction of this transmitter the maximum depth at which U-boats could receive was 13 to 15 meters.
 
 
 
 
VH/F GEAR:
 
 
 
 
        Prisoners state that the the "Tornistergerät" is used for both telegraph and voice traffic.  It is used exclusively
 
 
 
 
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  during trials in the Baltic and never on patrol.  This traffic is ciphered in the usual way, and carried on VH/F (U.K.).  All radiomen from U-664 and U-841 are positive that U-boats on patrol are no longer equipped with VH/F sets.  Use of this equipment had been discontinued on patrol because of the very great danger of D/F'ing by the enemy.  
     
 
MISCELLANEOUS INFORMATION.
 
 
 
 
        Prisoners state that there is an area of notably bad reception (Todtpunk) off the coast of Newfoundland.  A radioman from U-841 states that he was told that the enemy practiced deception on "Kurzsignale" which messages begin with the symbol Beta twice repeated followed by a three letter group then two or three four-letter groups and a signature consisting of a three letter group.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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S E C R E T
 
   
 
CHAPTER V.  GUNS AND GUNNERY
 
     
 
ARMAMENT.
 
 
 
 
        As indicated above, U-841 had a 105 mm. gun on her forward deck, demountable machine guns (M.G. 15) on the bridge, 2 single 20 mm. guns on platform I, one quadruple 20 mm. gun on Platform II.
 
 
 
 
        When first built, she had the 105 mm. forward, the demountable machine guns, no guns on Platform I, one single 20 mm. gun on a small Platform II and one 37 mm. gun on her after deck.  This state of armament remained until the final overhaul in Stettin when the 37 mm. was removed and a single 20 mm. gun was mounted on Platform I.  It was with this armament that she expected to go on patrol from Kiel late June or early July, 1943.
 
 
 
 
        However, the remodeling of the Conning Tower structure in Bremen during July again changed the picture.  Platform II was removed and a pre-fabricated, larger and stronger Platform II was added.  On this new platform, a quadruple 20 mm A/A gun was mounted.  A second single 20 mm gun was added to Platform I, and the two 20 mm.'s were placed symmetrically to port and starboard.
 
 
 
 
        A well, about 150 mm. (6 inches) in diameter was located in the deck of Platform II between the quadruple 20 mm. and Platform I.  Sea water was kept in this well which was to be used to immerse the barrels of the quadruple 20 mm. if and when they became hot.  This cooler was not used on the patrol.
 
 
 
 
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  105 MM. GUN.  
     
 
        The 105 mm. gun was adapted for A/A use by means of a special mount that permitted elevation to 700 and depression to 100.  One turn of the elevation hand wheel was claimed to have elevated or depressed the gun 100.  It had a traverse of 1200 to port and to starboard (one prisoner insisted it was only 1100 to starboard).  One turn of the traversing hand wheel was claimed to have trained the gun 100 right or left.  The rifling was said to have 3-1/2 turns and 32 lands.  This gun had no splinter shield or armor of any kind.
 
 
 
 
        The sighting gear seems to have been conventional.  There was a telescopic sight both right and left, which consisted of two eyepieces set at right angles.  Number 1 looked into the side eyepiece, Number 2 used the other.  Instead of crossed hairs, the telescopic sight had four small arrows which did not quite meet in the center.  One prisoner stated there was an open sight inboard of the telescopic sight, which consisted of a rear sight and a bead front sight.  The Azimuth gear and range dial were located on the left side of the gun on the recoil housing and were manned by Number 3.
 
 
 
 
        The rate of fire was claimed as high as 25 rounds per minute, but a prisoner who had taken both the gunnery courses and an A/A course stated that 6 or 7 per minute was the rate of fire per minute in combat from a surface vessel, and even up
 
 
 
 
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  to 15 rounds per minute under ideal circumstances in practice.  The same gunner claimed that they had achieved 10 to 12 rounds per minute in practice.  He felt that that was a good performance.  
     
 
        The crew of the 105 mm. consisted of six men and an extra passer:  Number 1 was the pointer and fired when ready; Number 2 was the trainer; Number 3 was the sight setter; Number 4 was the plug man; Number 5 was the loader and called "ready!" when the breach had been closed.  Numbers 6 and 7 were passers.
 
 
 
 
20 MM. QUADRUPLE GUN.
 
 
 
 
        The quadruple 20 mm. gun was mounted on Platform II.  It was actually 4 single 20 mm. guns (C-38's) on a single mounting (C-41 or C-42) with splinter shield through which the 4 barrels projected and which had a hinged armored wing on each side.
 
 
 
 
        This quadruple 20 mm. could be elevated 900 and depressed 100.  It had a traverse of 3600, with an automatic stop that forced elevation to clear the conning tower structure forward of Platform II and prevented depression that would damage the after decking.  Both these stops could be disengaged at will.
 
 
 
 
        Prisoners asserted that their quadruple 20 mm. was the same as the land gun, except for the mounting.  (O.N.I. Note:  This land gun has been described in detail in APG, Aberdeen, Md. Project # FMAR-213, 5 Oct, 1943.)  The rate of fire was 4 times that of a single 20 mm. gun or about 600 rounds per minute.  The crew of the quadruple gun comprised 4 men:  Number 1, trainer who
 
 
 
 
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  also fired; Number 2, pointer; Numbers 3 and 4, loaders, left and right respectively.  
     
 
        The magazines were not fully loaded, but one or 2 shells were left out in order to save the springs.
 
 
 
 
        The center section of the splinter shield of the quadruple gun was about 15 mm. thick, with openings for the four barrels.  The wings were hinged and kept folded parallel to the keel line when not in action.  They could be opened out to form an angle of about 1500 with the center section.  These wings were reinforced in the center with armor plating about 20 mm. thick.  The dimensions of the armor plates were variously stated but seem to have been different on the two sides.
 
 
 
 
SINGLE 20 MM. GUNS.
 
 
 
 
        There were 2 of the C-38 model, single barrel 20 mm. guns on Platform I.  These well known guns were served by 2 men.  Their rate of fire was given as high as 250 rounds per minute.  Sights for these guns were described as follows:  a front sight of 2 concentric circles with crossed lines through both and lines at 450 intervals between the crossed lines from the outer to the inner circle.  The rear sight was of V-type.  There was no protection of any kind on these guns.
 
 
 
 
MACHINE GUNS.
 
 
 
 
        Four demountable M/G 15's were carried aboard U-841.  They were not used on the patrol.  They were kept in the Conning
 
 
 
 
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  Tower by the ladder and in the passage way by the captain's cabin.  
     
 
        These M/G's were drum fed.  The drums contained 35 to 40 rounds.  Some were kept in the Conning Tower.
 
 
 
 
AMMUNITION STOWAGE.
 
 
 
 
        The main Magazine on U-841 was below the deck of the Control Room.  The decking opened just beneath the ladder to the Conning Tower.  In the Magazine was stowed the greater part of the 20 mm. ammunition and about half the 105 mm. shells on board.  The 20 mm. shells were stowed in chests of 100 rounds each;  the 105 mm. shells were stowed in their individual containers.  Two chests of 20 mm shells were carried on this patrol in the Control Room, since the magazine was too full.
 
 
 
 
        Abaft the 105 mm gun there was a deck well with a partition on the keel line and a hatch which opened in 4 sections.  In this well 60 shells, as ready ammunition, were stowed in pressure proof containers set on end at an angle of about 300 in 6 rows of 5 shells each on either side of the partition.
 
 
 
 
        Pressure-proof containers for ready use 20 mm. magazines were located on Platforms I and II.  The former had only one, on the keel line abaft the 2 guns; the latter had 4 such containers, 2 on each side of the quadruple gun.  These containers held 12 to 15 magazines each.  The first 4 were placed vertically in the containers, the rest lay flat.  A removable framework held the magazines in the containers which extended as foot or more above the deck level and were about 20 inches in diameter.  (O.N.I. Note:
 
 
 
 
- 38 -
 
 
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  Since the magazines were loaded with 18 rounds, it is reasonable to estimate 1200-1300 rounds of 20 mm. ready ammunition above decks.)  
     
 
AMMUNITION PASSING.
 
 
 
 
        The problem of getting ammunition on deck from the magazines and distributing it was solved as follows:
 
 
 
 
        A man in the Magazine passed shells or loaded magazines to another in the Control Room.  He in turn relayed the ammunition to a man on the ladder to the Conning Tower who handed it to one sitting in the Conning Tower hatch.  This man gave it to another standing in the Conning Tower who passed it to a man sitting in the bridge hatch.
 
 
 
 
        If this man was passed a 105 mm. shell, he put it into either the port or starboard opening in the forward Bridge fairing, through which it slid down a short steep (ca. 500) chute to Number 7 of the 105 mm. gun crew on the forward deck.  The latter passed it to Number 6 who in turn passed the shell to Number 5 who loaded the gun.
 
 
 
 
        If a 20 mm. magazine reached the Bridge, it was handed to a passer to Port or Starboard who would then give the magazine to Number 2 of the 20 mm. gun crew.  More were passed to the man to starboard, since he also had to feed magazines into the chute from the Bridge to Platform II for the quadruple 20 mm. gun.  This chute is unique with U-841.  It was put on at Klt. Bender's personal insistence.  Some claim he invented it himself.  Its success was not agreed upon by prisoners, but it is certain that
 
 
 
 
- 39 -
 
 
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  it had no real combat trial.  A passer stood by the lower opening of the magazine chute and handed magazines alternatively to Number 3 of the quadruple crew or to the second passer who in turn gave the magazine to Number 4 of the quadruple crew.  
     
 
105 MM. AMMUNITION.
 
 
 
 
        There was but one type of 105 mm. ammunition taken on the sole patrol by U-841, namely A/A shells.  These could be set to any desired range by turning the head with a key on the order of a wrench.  For practical reasons, the ready ammunition was set in advance at 3,000 m. and 1,500 m.  The former was marked with a white "W" meaning "weit" (distance), and the latter with a white "N", meaning "nahe" (near).  These settings could be changed at will, and would be, if these H.E. shells were to be turned against surface targets.  They could be set either by seconds or on contact.
 
 
 
 
        The muzzle velocity of 105 mm. shells was given as 1,200 m.p.s.  (O.N.I. Note:  This seems most unlikely; the stated muzzle velocity of 105 mm. shells in British reports of 2,132 ft. per second is more probably that of the 105 mm. projectiles carried by U-841.)
 
 
 
 
        The color of the 105 mm. A/A ammunition was red; some informants claimed red and white stripes while another source insisted the white was merely polished, unpainted metal.  The letters "W" and "N" indicating the zone setting were painted on the shell containers as well as on the projectiles themselves.
 
 
 
 
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          The probably maximum range of the 105 mm. shells is 12,000 m.  When these shells burst, they hurl some 2,000 splinters in a danger zone of about 20 m. radius.  
     
 
20 MM. AMMUNITION.
 
 
 
 
        There were 184 boxes of 20 mm. ammunition on board, each box containing 100 rounds; 182 boxes were in the Magazine and 2 in the Control Room.
 
 
 
 
        The types of 20 mm. ammunition on board were reported to be as follows:
 
 
 
 
        Armor piercing delayed explosion - Blue, pointed.
 
 
        Armor piercing                             - Black, flat nose.
 
 
        Incendiary                                    - Yellow, flat nose.
 
 
 
 
        These were all said to come with or without tracer.  There was no agreement on loading order of these types.  Also, there was a great divergency of opinion on the types and color markings of 20 mm. ammunition, and the above is to be treated with the greatest reserve.
 
 
 
        It was generally reported that all the 20 mm. ammunition was self destroying at 2,100 m.  Thus these guns were not used until the attacking plane was within that range.  The muzzle velocity of the 20 mm. shells was stated to be 900 m. per second.
 
 
 
GUNNERY NOTES.
 
 
 
 
        The setting of the 105 mm. ammunition determined the
 
 
 
 
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  opening range for this gun, namely before the attacking plane or planes had reached 3,000 m.  This set up a barrage curtain at that distance.  If the plane or planes got through, the 1,500 m. setting shells were used forming a second curtain.  The 105 mm. was not expected to be used at closer range for A/A.  
     
 
        Since the 20 mm. shells were self-destroying at 2,100 m.  this was the opening range for the quadruple or single guns.  The practice with these guns was to lead the nose of the plane.
 
 
 
 
        The practice of firing alternate barrels of the quadruple gun seems to have been disregarded on U-841.  Any barrel could be fired separately or any number of the 4 barrels together.  It was not considered too awkward to feed magazines to two barrels at almost the same time.
 
 
 
 
        One of the differences between the C-30 and C-38 is that the C-30 has a handle cocking device whereas the C-38 has a chain device.
 
 
 
 
        It was claimed that the most common cause of jamming of the C-30 was breach trouble.  This lead to its discontinuance.  If loaded magazines for the C-38 were not serviced every two weeks, the gun was very likely to jam.  Otherwise it was much more reliable than the C-30.
 
 
 
 
        The C-41 of the German Army has a higher rate of fire, but is said to be not adaptable for U-boat use.
 
 
 
 
        Although the four barrels of the quadruple 20 mm.
 
 
 
 
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  gun converged, the point of convergence of the shots fired was beyond the range at which the projectiles burst, so that there was no convergence point in combat fire.  
     
 
        Remote fire control was not used on U-841, nor did any of her crew know of its use in the U-boat Service.
 
 
 
 
        The first few shots were said to be aimed with the ring sight and then the tracer was relied on for aiming.
 
 
 
 
GUNNERY OPINIONS ON U-841.
 
 
 
 
        It was felt that the 105 mm. was not satisfactory as an A/A/ gun and would be discarded as the 88 mm. has.  Its slow practical rate of fire and its size which tends to increase the diving time are bringing it into disfavor.
 
 
 
 
        The quadruple 20 mm. gun is considered a disappointment.  It is too complicated and bulky, too easily damaged by the force of the water, as was the one on U-841, to be reliable.
 
 
 
 
        There is a double-barreled 20 mm. gun which is not 2 separate guns which is planned for use on U-boats.
 
 
        Opinion varied on the practicability of the twin 37 mm. gun.  Its increased fire power was admired, but it was held to be too bulky for use on a U-boat.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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CHAPTER VI.  CREW OF U-841
 
     
 
        The Commander and all officers, except the Executive, were lost with U-841.
 
 
 
 
        Kapitänleutnant Werner Bender, Captain of U-841, entered the Navy in 1936 and made his midshipman cruise on the Schleswig-Holstein in 1938.  He sailed on two patrols as First Watch Officer under Korvettenkapitän Albrecht (Ajax) Achilles.  (O.N.I. Note:  This was probably in U-161).  He was 27 years old.
 
 
 
 
        The more experienced members of the crew looked upon Bender as representative of the young officers now being given command of U-boats.  U-841 was Bender's first command.  He joined the boat during her first stages of construction in Bremen.  During her trials in the Baltic he made a brilliant record.  A strict disciplinarian, he was generally well liked and respected, looked upon as a spirited and promising officer.  Lack of experience, however, led him into a fatal mistake and the loss of his boat.
 
 
 
 
        The executive Officer was Leutnant zur See Herman Knaup, 23, of the December 1939 Naval Term.
 
 
 
 
        After the fall of France Knaup was a member os a party of 100 sent to La Pallice to requisition boats and arms and organize a mine sweeper flotilla.  Following service with this flotilla, he was Executive officer on a training U-boat of the 24th Flotilla at Memel.
 
 
 
 
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S E C R E T
 
   
          With U-841 from the beginning, Knaup won the unqualified dislike and distrust of all ranks on board.  He was inexperienced, harsh, and capricious with the men, given to talking for effect before his superiors.  There is some evidence that he attempted to malinger out of the ill-fated patrol of U-841.  In action he was nervous to say the least.    
     
 
        Leutnant zur See Ernst Huffmann of the October 1940 Naval Term served as Second Watch Officer with U-841 from her commissioning until just before her sailing from Trondheim.  He was said to be the son of a Major General now serving on the Russian Front.  Before joining U-841 he had been a platoon commander in the 3rd company of the U-boat Training Detachment at Neustadt.
 
 
 
 
        Huffmann was held in very high esteem by all his subordinates.  His captain, who did not share the crew's enthusiasm for this young officer, found him forgetful, immature, and given to too much familiarity with the men.  In Swinemünde Huffmann discovered that he had left the key to the code machine in Stettin.  One of the radio ratings volunteered to retrieve it, and after a night of almost unbelievably picaresque adventures returned with the missing key before its loss had become known.
 
 
 
 
        In Bergen Huffmann's memory played a far more serious trick.  After a night of drinking he left a number of secret documents in a hotel room.  It was stated that some
 
 
 
 
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  of the documents were missing when the Gestapo returned the remainder to the boat in Trondheim.  The reckoning was more than Huffmann could face.  He went up into the hills, burnt his shoulder boards, and insignia of rank and committed suicide.  
     
 
        Huffmann was succeeded as Second Watch Officer by Oberfähnrich zur See Nahrgang, 23, of the May 1941 Naval Term.  From all accounts Nahrgang was an excellent young officer, firm, competent, and considerate.  His previous experience included two patrols in the Mediterranean under Kapitänleutnant Koenenkamp in the Summer of 1942.  (O.N.I. Note:  This was probably in U-375, at that time based on La Spezia).  He was a member of the Personnel Reserve at Trondheim when he was assigned to U-841.
 
 
 
 
        The Engineer Officer of U-841, Oberleutnant (Ing.) Max Hörig, joined the Navy in October 1937.  He is said to have had better connections and to have had a more firmly established reputation with the high command than his captain had.  The German Navy list does not show him as a lower deck promotion but he was so regarded on board.  The men in general felt that, having to come up through the ranks, he had more insight with their problems.  The respected his leadership.
 
 
 
 
        U-841 carried a doctor, Marinestabsarzt Dr. Rudolf Brautigam who joined the Navy in 1940.  He spent a good deal
 
 
 
 
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  of his time in the radio and listening rooms but it was denied he had any official duties there or had received any technical training in communications.  
     
 
        A midshipman left U-841 at Hela where two other midshipmen joined her.  It was at first expected that they would go on active patrol with U-841 but after remaining on board during the Active Service Training Group Exercises at Hela and the torpedo firing practice in the Gulf of danzig, they were unexpectedly sent to Watch Officers Training School.  One of these midshipmen was said to be Oberfähnrich Hentzling.  (Not in G.N.L.)
 
 
 
 
        Some of the older petty officers were men of judgment and experience, having sailed with such U-boat captains as Endrass, Achilies, Hardegen and Moehle.  The crew on the whole, however, were young and immature.
 
 
 
 
        Two men serving in the Merchant Marine were caught abroad at the outbreak of war, one successfully ran the blockade; the other was sunk in the Bay of Biscay and spent a brief period in a French prison camp.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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S E C R E T
 
   
 
CHAPTER VII.  EARLY HISTORY OF U-841
 
     
 
        U-841 was launched in the latter part of November 1942 at the Deschimag yard in Bremen.  Her crew gradually collected during the final stages of construction and stayed with her, with a few exceptions, until the sinking.
 
 
 
 
        The commissioning took place 6 February 1943, at which time the boat was assigned to the 4th Flotilla at Stettin.  She remained attached to this Flotilla until her final overhaul was completed.  She was then transferred to the 2nd Flotilla at Lorient.
 
 
 
 
        After taking on supplies and otherwise getting shipshape, U-841 put out from Bremen on the morning of 13 February 1943.  She proceeded only as far as Bremerhaven that day and put up overnight in the destroyer basin by the old locks.  The crew slept in the Destroyer barracks.  The next morning, she set out with one escort vessel and arrived at Hamburg-Trollerort at 2300 hours.  There part of the crew stayed aboard the depot ship Veendam.  The morning of 15 February, tests were made with the radar which lasted some 5 or 6 hours.  U-841 moved on to Brünsbüttel directly after these tests and spent the night there, since boats are not allowed to use the Kiel Canal after dark.  Most of the crew slept ashore in barracks.
 
 
 
 
        On the morning of 16 February at 0600, U-841 set out from Brünsbüttel and made the passage of the canal in 9 hours, arriving in Kiel-Wik where she tied up at the Albatros
 
 
 
 
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  Jetty at 1500 hours.  At 1530 inspection by the Flotilla Commander was held; several crews, including that of U-841 were addressed by K.K. Mohle, the Commanding Officer of the 5th Flotilla at Kiel.  The first Kiel visit lasted approximately 2 weeks, during which the usual U.A.K. (U-boats Acceptance Command) tests were undergone.  The crew lived in the Northern Barracks on this visit.  The boat was depermed early in the stop-over.  Before moving eastward for further trials and exercises, various excess supplies were stowed aboard St. Louis until U-841 should be ready to put out on her first war patrol.  The pressure test was carried out in half a day in the tubular pressure dock at the Howaldt Werke.  Only a few of the crew and some "Silberlinge" (Engineering Corps Officers) remained aboard.  
     
 
        One episode during the U.A.K. period deserves note.  U-841 did not undergo the silent running tests at Rönne, Bornholm Island, as had been routine in the past, but proceeded to Sonderburg, Denmark for these tests.  Leaving Kiel one morning, the boat arrived at Sonderburg in the afternoon and immediately made the prescribed runs.  Then she tied up for the night, and the crew were given 5 Kroner with which to make 4 hours liberty a pleasant memory.  It was claimed by some of the crew that the sustained A.K. speed trial was run on the say to Sonderburg, but this statement was emphatically denied by reliable prisoners who insisted that this test was
 
 
 
 
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  held on the way to Swinemünde from Kiel.  
     
 
        During the first few days of March, U-841 cleared Kiel for Hela, Gotenhafen and Danzig.  She put into Swinemünde that evening and tied up for the night.  The next two days were spent in A/A exercises, theoretical and practical.
 
 
 
 
One half the crew went out each day for drill in firing the 20 mm. guns and the 37 mm. gun.  Each man on board, including the cook and the doctor fired 15 rounds from the 37 mm., and an unstated quantity of 20 mm. ammunition.  Approximately 2,000 rounds of the latter were fired in the two days.  It was claimed that 30 rounds each day were fired from the 105 mm. also but this was denied by some.  Part of the crew lived on a small steamer serving as depot ship there.
 
 
 
 
       Early in the morning of the third day the boat put out from Swinemünde and ran up to Stettin where she unloaded further extra equipment.  Part of the crew spent the night aboard the depot ship Usambara.  The next morning U-841 set out for Danzig.
 
 
 
 
        She lay over at Danzig for about a week.  Most of the crew lived aboard the depot ship Iberia, near which their boat was berthed.  At this time the U.A.G. (U-boat Acceptance Group) trials including the measured mile run, were carried out.  The day after their arrival, the crew was ordered by Bender to paint all top and side surfaces very light gray.  It was insisted that this was entirely on Bender's initiative; no one seemed to know why it was ordered.  The T.E.K. (Torpedo Testing Command trials were held in Neufahwasser where water
 
 
 
 
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  slugs and a few dummy torpedoes were fired.  
     
 
        Upon completion of U.A.G. and T.E.K., U-841 sailed over to Gotenhafen where provisions were shipped.  It was necessary to wait over a second day for canteen supplies.
 
 
 
 
        After this brief first Gotenhafen visit, the boat moved across the bay to Hela where the approximately 4-week Agru-Front was held.  The depot ship used by the men while they were in port there was an old, small, river vessel named Preussen.  In the midst of this phase of the trials, 5 days of so-called "Vortaktische Uebungen" (Pre-Tactical Exercises) occurred in which U-841 exercised with about seven other boats.  The crews  stayed aboard the entire time.  There were conflicting statements about staying out or running in late each night.
 
 
 
 
        During the Hela visit, a tragedy occurred which delayed U-841 in her training about half a day.  A 500-ton boat, which could not be identified by number or commanding officer, signaled an emergency dive while her Commander, Executive Officer, and one other man were on deck inspecting a gun.  They jumped into the Conning Tower but could not close the hatch to the bridge and, as the boat submerged, water started to pour into her.  A boatswain's mate secured the control room hatch to the Conning Tower and thus saved the boat.  She was checked in her dive at 20 meters depth and immediately surfaced.  However an estimated half hour to one hour was required to pump the Conning Tower dry, and the three trapped men were dead.  Klt. Bender was ordered to take the boat over to Gotenhafen and
 
 
 
 
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  return by rail to Hela.  
     
 
        Because she was not clear for her tactical exercises when such a group was beginning, U-841 went from the Agru-Front at Hela to the torpedo-firing exercises in Danzig.  These exercises lasted 10 days and were ended 24 April.  The boat lay over in Danzig over Easter, for the convenience of the crew.
 
 
 
 
        During this second visit to Danzig, U-841 lay in the U-basin, and the crew lived aboard the depot ship Deutschland.  Sea targets were fired at with "everything on deck" from which it must be concluded that the 105 mm., 37 mm., 20 mm., and M.G. 15's were used.  Klt. Bender was said to have been very skillful in the torpedo-firing exercises, and great hopes were raised for a successful career for U-841.
 
 
 
 
        The tactical exercises lasted from 1 May to 10 May 1943 and were the reason for the second Gotenhafen visit.  It was stated that 8 other boats took part in these exercises.  Submerged attacks were made by day and surface attacks were practiced at night.  U-841 made a navigational error at one time during the tactical exercises and lost the convoy.  She regained it again by the use of her Fu.M.G.  The convoy comprised some 5 Merchant Ships and at least 8 "Destroyers"), some of which were old French and Belgian gunboats, the others were converted fishing vessels.  Klt. Ernst Bauer, K.C.I.C. was in charge of the tactical exercises which he directed from Wilhelm Bauer.
 
 
 
 
        A second tragedy to another boat occurred at
 
 
 
 
 
 
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  Gotenhafen while U-841 was there.  On returning from exercises, a U-boat suddenly sank at the entrance to the harbor.  There was no explanation known to the crew of U-841, who claimed that the salvage had not been attempted while they were there.  Only two men escaped:  A Leutnant zur See Fröhlich.  (O.N.I. Note:  Probably Günther Fröhlich of the Naval Term of 1939)  who had been the company commander of one of the prisoners during his boot training, and an enlisted man.  Informants were unable to identify this boat by number or commander,  
     
 
        From Gotenhafen U-841 made for Stettin where final adjustments and an overhaul were carried out a the Oderwerke.  This procedure lasted from 12 May to 24 June, in the course of which:  all ten pressure-proof deck containers for torpedoes were removed; the 37 mm. gun was removed; a 20 mm. single barrel gun was mounted on Platform I; the U-boat was again painted gray.  Beyond these items, only usual, routine repairs and adjustments were made, since the boat had suffered no damage to date.  The crew were stated to have lived in barracks and received leaves from 10 to 16 days in length.  Torpedoes and all kinds of supplies were taken on before leaving Stettin in anticipation of setting out soon from Kiel on patrol.  Upon leaving Stettin, U-841 was transferred from the 4th Flotilla to the 2nd Flotilla, at Lorient.  Subsequent changes in plans placed her in an unusual if not anomalous relation to her Flotilla.
 
 
 
 
        On the way from Stettin to Kiel, U-841 stopped for 2 days at Swinemünde for her second visit. A/A exercises were carried out in which some 1500 to 2,000 rounds of 20 mm. ammunition
 
 
 
 
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  were fired.  There was a difference of opinion as to whether the 105 mm. gun was fired or not; at the most only 10 rounds were claimed as fired at this time.  
     
 
        On June 27 1943, U-841 returned to Kiel in expectation of an early departure.  The crew lived aboard St. Louis.  A G.S.R. was expected at this time, but not received.  Four hours before their supposed sailing, a signal was received ordering the Commander to report to the 5th Flotilla Headquarters aboard the St. Louis at once.  Upon his return, he announced the cancellation of their sailing orders and the fact that they were to proceed to Bremen.  Torpedoes and other supplies were again unloaded in Wik at #17 Tirpitz Mole.  They sailed for Bremen via the Kaiser Wilhelm Kanal 5 July 1943 and spent that night in Brünsbüttel.
 
 
 
 
        At 1800, 6 July, U-841 arrived at Deschimag yard, Bremen, and the one month task of remodeling the Conning Tower structure got started.  Platform II was removed and a new, larger one was built on in its place.  A quadruple 20 mm. A/A gun was mounted on this stronger structure with its 4 pressure-proof ready ammunition containers built around the gun mount.  A second 20 mm. single barrel A/A gun was mounted on Platform I.  The crew were housed in barracks ashore and given 10 day leaves in 2 shifts.
 
 
 
 
        U-841 put out again 4 or 5 August from Bremen.  She lay overnight at Bremerhaven and arrived at Brünsbüttel the next day.  There she tied up for the night and made the
 
 
 
 
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  passage of the Kiel Kanal the day following, arriving in Kiel 7 or 8 August.  
     
 
        The 3rd Kiel visit lasted only about 3 days.  U-841 then proceeded to Swinemünde for her 3rd visit there.  This time bad weather interfered with the smooth execution of the A/A exercises and prolonged the stay one day.  Between 3,000 and 3,500 rounds of 20 mm. ammunition were fired and the new quadruple 20 mm. A/A gun was proof fired.  It was again claimed that 10 rounds were fired from the 105 mm. although this was again denied by some.
 
 
 
 
        U-841 reached Stettin from Swinemünde 15 August 1943 in the late afternoon or early evening and 14 torpedoes were taken aboard that night.  This 3rd Stettin visit lasted a day and a half, and then the U-boat cleared for Kiel, arriving there 18 August.
 
 
 
 
        This last visit to the port of Kiel - U-841's fourth - was spent in awaiting sailing orders, taking on some supplies, and running outside two nights to avoid possible air raid damage.  Finally at 0800, Thursday, 26 August 1943, she put out from Kiel on her first patrol, which was to be also her final patrol.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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S E C R E T
 
   
 
CHAPTER VIII.  FIRST AND FINAL PATROL OF U-841
 
     
 
        The departure of U-841 from Kiel was preceded by an address by Kapitänleutnant Metzler acting in the place of Korvettenkapitän Möhle who was on leave (O.N.I. Note:  Kapitänleutnant Metzler is of the 1931 naval term; he was with the 5th Flotilla, at Kiel having been transferred from command of U-847 because of illness.)  At 0800, 26 August 1943, in company with a 1600-ton combination minelayer and supply U-boat commanded by Korvettenkapitän Burghagen and two 500-ton U-boats, one of which was U-643 commanded by Kapitänleutnant Hans Harald Speigel (O.N.I. Note:  U-643 was sunk 8 October 1943 near 560N., 80W. by 2 Liberators while a member of "Gruppe Rossbach" attacking a convoy, presumably the same against which U-841 was proceeding at the time of her sinking.  Kapitänleutnant Speidel is a P/W.)  U-841 put out from Kiel escorted by a mine destructor vessel and another, smaller vessel.  These latter ships were relieved at different points en route.  They could make only 10-12 knots and thus slowed the uninterrupted run to Kristiansand which was reached between 2200 and 2300, 28 August.
 
 
 
 
FIRST PATROL TASK.
 
 
 
 
        The next morning at 0400, the same 4 U-boats put out and ran along the Norwegian coast to Haugesund where they arrived that evening.  There U-841, U-643, and the second 500-tonner were ordered to put about and proceed to Skaggerak.
 
 
 
 
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  U-Burghagen proceeded from Haugesund to Bergen, much to the envy of the other crews.  Arrived in the Skaggerak, the three boats patrolled back and forth to prevent the escape of the Danish Fleet. It was believed that other U-boats also took part in this task.  The only action on this assignment was between U-841 and an incautions German fighter plane against which U-841 turned her quadruple 20 mm. A/A gun with success.  It was understood that the flyer managed to come down in Norway.  
     
 
        At about noon of 1 September 1943, U-841 and the two 500-tonners (one of which was U-643) were met just outside the Skaggerak by a mine sweeper and escorted to Egersund where they spent the night.  The next day they set out for Bergen with an escorting vessel and arrived at 1700 hours.   
 
 
 
 
SOJOURN AT BERGEN.
 
 
 
 
        During the 10 days or so spent in the port of Bergen, U-841 had diverse experiences.  She was drydocked while a leaking stuffing box on a propeller shaft was made tight; deep dives were practiced, going as far as 180 m.; a run was made to Björner Fjord for special exercises; and the Second Watch officer lost a briefcase containing secret documents.
 
 
 
 
        The one-day visit to Björner Fjord from Bergen was for the purpose of participating in pursuit and evasion tactics exercises with other U-boats and several "destroyers" (for details see Chapter XII, Bases).  Several foreign U-boats in the German Service were seen in the course of this visit.
 
 
 
 
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          Leaving Bergen 13 September 1943, U-841 headed northwards for Trondheim.  The boat arrived in Aalesund about 2200 hours and lay over in the South Harbor.  No other U-boats were noticed there.  The following morning she put out at 0600 and tied up in Trondheim at 1630.  
     
 
WAIT IN TRONDHEIM.
 
 
 
 
        The stay of approximately 3 weeks at Trondheim was occasioned by the delayed arrival of a new, more sensitive G.S.R. set known as "Wanz".  This was eventually flown in from Germany and installed with the greatest secrecy.  In the meantime, there was A/A firing practice, diving practice, and taking on of various supplies including oil and ammunition for the 20 mm. guns.  Ammunition for the 105 mm. gun other than A/A type was put ashore, and 30 or 40 rounds of the latter were taken aboard at 1130 Monday, just before the time set for sailing.  A tooth on the training gear of the 105 mm. gun was repaired.  The gun had been poorly secured, and the tooth had been broken by swinging of the gun while under way.  Two men were sent ashore on account of venereal disease.  They were replaced by Trautes and Jensch.
 
 
 
 
SUICIDE.
 
 
 
 
        The high point of this stop-over was the suicide of Leutnant z. S. Ernst Huffmann on the night of 24/25 September already recounted in Chapter VI.  Kapitänleutnant Bender addressed the crew of U-841 at the announcement of Huffmann's death, described him as a blackguard, and forbade
 
 
 
 
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Click this text to view Plate H  Track Chart of First and Final Patrol of U-841

     
 
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  anyone to attend his burial.  This had a depressing effect on the crew with whom Huffmann was very popular.  Huffmann was replaced by Oberfähnrich Norbert Nahrgang who came aboard 29 September.  
     
 
DEPARTURE FOR OPERATIONS.
 
 
 
 
        U-841 finally sailed from Trondheim at 1400 Monday 4 October 1943.  She was accompanied by a minesweeper for six hours or more.  The U-boat ran on the surface for about 24 hours.  Then followed nearly 10 days of underwater running with surface cruising of only a few hours each night to charge the batteries and ventilate the boat.  A heavy sea was running the entire time.  No ships were sighted and no torpedoes fired.
 
 
 
 
PLANES SIGHTED.
 
 
 
 
        Just before turning into the "Rosengarten", U-841 picked up some planes with her G.S.R.  Later on in the "Rosengarten, planes were sighted.  In both instances the boat dived and escaped unnoticed.
 
 
 
 
COURSES.
 
 
 
 
        Plate H shows track chart of this Patrol.
 
 
 
        On leaving Trondheim, U-841 followed a course of about 2780 until sometime during 7 or 8 October; then at approximately 650 N., 80 W., she turned into course 2200 or 2300, by means of which she traversed the "Rosengarten".  Statements, uncertain at best, differ from then on:  some claim a second turn was made at 580 N., 200 W; others insist that she continued
 
 
 
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  on course 2200 until the signal was received announcing the convoy.  This seems to have been about 550 or 560 N.  Those who claim the turn at 580 N., 200 W., say they followed a course of 1700 to 1800 until the signal on the convoy was received at or near position 560 N., 200 W.  Others place their position at about 550 N., 250 W.  
     
 
        In either case, the signal was received 15 October, and a westward course (2700) was steered which shifted to 3100, to 3500, to 00, and finally 100.  (O.N.I. Note:  As vague and conflicting as statements were on the courses steered, the above track actually will lead from either 560 N., 200 W., or 550 N., 250 W. to 590 N., 310 W., near which position U-841 went down.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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CHAPTER IX.  SINKING OF U-841
 
     
 
        There were thought to be 12 or 13 U-boats in the pack named "Gruppe Schlieffen" attacking Convoy ONS 20 (designated as "Cycle" by the Germans) on the afternoon of 17 October 1943.  Among these U-boats, U-841 was proceeding full speed on the surface towards the convoy on course 100 (also stated as course 500).
 
 
 
 
        She had learned by radio that 3 other U-boats had been sunk, including U-964, believed the Contact Keeper, and that 3 men from one of them had been rescued (presumably by another U-boat).
 
 
 
 
        At 1550 Z, an airplane was sighted by the bridge watch of U-841.  Klt. Bender ordered the boat to stay surfaced.  It is not known what determined his decision.  Twice U-841 had sighted aircraft and dived to safety.  However, she had picked up radio reports from 2 nearby U-boats of their successful resistance to aircraft attacks.  In the present instance it seems improbable that the aircraft had first sighted U-841.  She was certainly beyond the 5000 meter range of mandatory combat laid down by B.d.U.  Whether Bender wanted glory or just had confidence in his boat's firepower, his decision to fight it out on the surface was bitterly criticized by his more experienced subordinates.
 
 
 
 
        The quadruple and single 20 mm. guns were manned.  The M.G. 15's were not mounted.  The 105 mm. on the forward
 
 
 
 
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  deck was not manned on account of heavy seas.  In less than 10 minutes, the plane, a Liberator, came at them dead astern out of the clouds at about 1500 meters.  Four magazines were fired from the 3 barrels of the quadruple 20 mm.; the fourth barrel was out of commission due to a broken bracket supporting the barrel.  Both armored shields of the gun had been thrown overboard, because one of them had worked loose and produced a noise when submerged.  The 20 mm. guns on Platform I fired on the plane.  Hits were observed, but they were not effective.  It was said that the bullets could be seen bouncing off the armor of the plane.  
     
 
        In a well timed maneuver, Bender turned his boat to starboard and the 4 bombs released by the plane fell, one to starboard and three to port.  However, the shook the boat severely.  The bomb explosions momentarily forced her down by the stern, so that the men serving the quadruple 20 mm. gun were suddenly neck deep in water and water poured into the Conning Tower hatch for a moment.  The Captain at once ordered the boat dived, and she was away before the plane could get set for a second run.
 
 
 
 
        Considerable damage resulted from these near misses:  glass was broken; the main lighting system was knocked out; depth gauges were broken; stores scattered; there was some water entry in the stern compartment through No. 5 tube, and some in the electric motor compartment; an oil tank was ruptured; one battery was said to have been broken; and one
 
 
 
 
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  after horizontal rudder had to be worked by hand.  Only part of a signal announcing the attack could be sent before the radio went out of commission.  
     
 
        The initial dive was to 60 m.  but U-841 returned to 40 m. after about 15 minutes.  She stayed down nearly 2 hours before the first D/C's were heard.  During this time the Engineer Officer had recommended that all the oil be pumped out of the broken tank at once.  Bender turned down this suggestion.  The crew felt that the resultant oil slick must have betrayed them to the frigate which later sank them.  (O.N.I. Note:  From the Action Report from H.M.S. Byard, it seems no oil slick was observed, but that she located U-841 by use of her Asdic.  This was not known to the survivors.)
 
 
 
 
        At about 1800 Z, D/C's were heard.  The attacking frigate, whose engines had been stopped ran in very slowly and her Diesels were at first mistaken for those of another U-boat.  She was almost overhead when a chemical SBT was discharged.  (O.N.I. Note:  This may account for the fact that H.M.S. Byard lost contact for a short while.)  Three patterns of 4 D/C's each were used by H.M.S. ByardU-841 was severely shaken.  The water entries became serious and 11 battery cells out of 20 checked were found broken.  Chlorine gas formed in the stern portion of the boat.  She went down involuntarily to about 120 meters, was out of trim, being heavy by the stern, and lost headway.  Trim was regained for 3 or 4 minutes by shifting the entire crew to the bow compartment.
 
 
 
 
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          Hot words were exchanged between the Chief Warrant Officer (navigational duties) and the Captain, after which Bender lost his nerve and ordered the tanks blown.  The air reserve had reached 40 kg. and the Chief Warrant Officer felt it useless to sacrifice the men to the Captain's bad judgment.  
     
 
        As the boat surfaced, the Captain went to the bridge and ordered "Abandon Ship".  However, he seems to have been completely flustered and in a rage, for he stood on the bridge and blazed at the frigate with his pistol.  Gunfire from the latter prevented manning of the guns of the U-boat and wounded some of the escaping crew; it did not penetrate the conning tower of U-841.  There was no order in their leaving the boat, but the enlisted men were less excited than the Captain, the Executive Officer, and the Doctor.  Finally a much scorned Austrian, Seaman 2/c, had the wit to wave his handkerchief as a sign of surrender.  The frigate saw this, at once ceased firing, and prepared to rescue survivors.  The boy was soundly berated by Bender, who was then seen to jump overboard without a life jacket and clutching his pistol.
 
 
 
 
        The Engineer Officer opened the vents before he came out of the Conning Tower hatch, the last man to leave the boat.  It seems doubtful if any scuttling charges were set when the boat was abandoned.  Only one member of her crew went down with her:  Radioman 3/c Reil, who refused to leave his bunk.
 
 
 
 
        Twenty-six men and the Executive Officer were gotten
 
 
 
 
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  safely aboard H.M.S. Byard before darkness set in and the proximity of other U-boats made further attempts at rescue dangerous.  All those saved were firm in their praise of their treatment aboard H.M.S. Byard, which without question had a favorable effect on the subsequent interrogation of prisoners.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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CHAPTER X.  SINKING, HISTORY AND DETAILS OF U-848
 
     
 
        The following information was obtained (1) from the sole survivor of U-848's sinking, but who died three days after being landed at Recife.  (the sinking of U-848 was confirmed by the message he scratched on the paddle of his life raft); (2) from prisoners from U-841 who had seen U-848 while at Kiel.
 
 
 
 
SINKING OF U-848.
 
 
 
 
        On 5 November 1943, a Navy plane out of Ascension Island, sighted a fully surfaced U-boat in position 10.09 S., 18.00 W., and immediately attacked it at 1125 Z.  From then on until the boat sank at 1900 Z, 10 attacks by two Army and four Navy planes were made and a total of 33 depth charges and 12 demolition bombs were expended.  Twenty survivors were seen in the water after the sinking but were not sighted again thereafter.  Attempts were made to divert a merchant ship to the scene of action, but they proved unsuccessful.
 
 
 
 
RESCUE OF LONE SURVIVOR.
 
 
 
 
        On 3 December 1943, in position 08.00 S., 31.32 W., U.S.S. Marblehead picked up a lone survivor from an U.S. Army life raft.  He was landed at Recife on 4 December 1942, but died on 6 December 1943.  Very little information was obtained from him, as he was delirious most of the time.
 
 
 
 
EARLY HISTORY OF U-848.
 
 
 
        U-848 was believed commissioned about 20 February 1943 at Deschimag.  She was the second of a series of 1200-ton U-boat beginning with U-847.  Her commander was Korvettenkapitän
 
 
 
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Click this text to view Plate I   Bridge and Platforms of U-848

     
 
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  Wilhelm Rollmann.  Nothing is known of her trials in the Baltic.  
     
 
FIRST AND LAST PATROL OF U-848.
 
 
 
 
        The departure date and course of U-848 is unknown, as was her operational area or her whereabouts until mid October.
 
 
 
 
        Early in October 1943, U-841 intercepted a warning signal addressed to U-848 to the effect that the Azores were occupied by the Allies.  A prisoner stated that U-848 was near the Azores at the time of U-841's sinking 17 October 1943.
 
 
 
 
        The only surviving member of U-848 mentioned the sinking of a 3,000-ton steamer.  (O.N.I. Note:  This may have been the British freighter Baron Semple, 4567 tons, which is considered overdue.  She was last seen by a plane from U.S.S. Cincinnati 2 November 1943, in position 45.23 S., 21.11 W.)
 
 
 
 
DETAILS OF U-848.
 
 
 
 
        Plate I shows arrangement of Bridge and Platforms on U-848.
 
 
 
Tonnage: 1200 tons.
   
Building Yard: Deschimag, Bremen.
   
Armament: Two twin-mount 20 mm. on Platform I; one quadruple mount 20 mm. on Platform II.
   
Bridge Armor: Forward part of Bridge, level of Platform I armored inside; forward part of Bridge, from Platform I and to deck level, armored on the
 
 
 
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  outside.  Armored doors between Bridge and Platform I.
   
Captive Helicopter: Carried in two (three ?) pressure proof containers on Platform I.  For further details see Chapter XI.
 
     
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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CHAPTER XI.  MISCELLANEOUS REMARKS ABOUT U-BOATS
 
     
 
TECHNICAL REMARKS ON DIESELS AND SUPERCHARGERS.
 
 
 
 
        G.W. Diesels also are fitted with a Sandner type supercharger drive, which uses oil and leaf springs for cushioning.  A V-type 2-cylinder reciprocating cooling water pump is driven from and eccentric on the crankshaft.
 
 
 
 
        Lubricating oil pumps are of the gear type, with valves that reverse automatically when engines are reversed.
 
 
 
 
        G.W. Diesels have water cooled exhaust valve chambers and seats.  Valves are not cooled.
 
 
 
 
        It was said that no more new G.W. Diesels were to be built, due to their excess weight.  Present stocks only would be used up.  G.W. Diesels are not built at Kiel, but at some interior point.  The comparative weight per horsepower of M.A.N. and G.W. Diesels is as follows:
 
 
 
 
        M.A.N.        2 Kg. per H.P.
 
 
 
        G.W.            3.2 Kg. per H.P.
 
 
 
        For blowing tanks with exhaust from M.A.N. Diesels, engines are run forward; for blowing with G.W. Diesels, engines are reversed.
 
 
 
 
        U-180, when undergoing tests at Memel, had aluminum alloy bearings in its 6 Maybach Zeppelin type Diesels.  Due to the high speed of these engines, 1200 R.P.M., the bearings broke down before the end of a patrol.  These tests were unsatisfactory,
 
 
 
 
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  with the result that the German Navy is still using conventional lead-tin bearing metal.  
     
 
        A 1200-ton U-Cruiser, possibly the same series as the above was said to be powered by 6 Mercedes-Benz S-Boat Diesels.  They are V-12 type, about 1400 H.P. each and run about 1200 R.P.M.  These engines are mounted in tandem, 3 to starboard, 3 to port, slightly inboard from the tail shafts, which they drive through Vulkan hydraulic clutches.  These engines have had their superchargers removed.  A 6-cylinder M.W.M. engine of the type used as main engines on smaller U-boats drives a supercharger for all six.  Another M.W.M engine, same type, is said to be used for driving a charging generator.
 
 
 
 
        On a U-boat lying at the yard at Stettin, superchargers of the type on U-841, but with several stages, had been installed.  Emergency speed R.P.M.s were raised from 480 to 580, but the engine temperatures ran too high.  The engine room temperature was said to be 700 to 800 C.
 
 
 
 
ELECTRIC WELDING.
 
 
 
 
        On U-841 electric welding was done by taking current from half of the armature of the motors/generator, or 1/2 of 110 volts.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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  CAMPAIGN TO CONSERVE OIL.  
     
 
        A warrant machinist stated that a captain made a tour to address engineering officers on the vital necessity of conserving oil.  As dirty oil tanks on a U-boat could hold only about 2000 liters, i.e., the oil from one engine, the rest of the used oil was customarily pumped overboard.  Now this oil was to be stored in barrels on the upper deck and delivered at the base on return from patrols.  This captain stresses the fact that Romania no was the sole source of oil and if Romania were lost, the U-boat campaign would be at an end.
 
 
 
 
SYNTHETIC OIL PLANT.
 
 
 
 
        The main plant of the Leuna synthetic oil works is still in operation and has not been badly damaged, according to P/W's friend from Halle.  Synthetic lubricating oil is said to be unusable by U-boats.
 
 
 
 
ORDERS TO U-BOATS ATTACKED BY AIRCRAFT.
 
 
 
 
        U-boats have orders not to dive when sighted by aircraft at a distance of less than 5000 meters.
 
 
 
 
PROPELLER NOISES.
 
 
 
        Radio ratings stated that they are able, on a U-boat, to distinguish the sounds of Diesel, turbine and regular steam engines but that the have considerable difficulty telling the difficulty telling the difference between boats with the same type of propulsion machinery, particularly when the other boat's engines are stopping and starting.
 
 
 
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  For example, U-841 mistook the frigate that sank her for one of the numerous U-boats in the vicinity.  Only when the approaching frigate's engine revolutions became definitely different from those of a U-boat at any of the customary speeds, was she identified as an enemy vessel.  By that time she was heading directly for, and was almost over, U-841; it was too late to make effective use of S.B.T.  
     
 
TACTICAL USE OF R.D.B.
 
 
 
 
        Two coxswains from U-841 stated that it is customary to use R.D.B. only at night.  If a boat is shadowing a convoy on the surface and is about to close in for an attack, 2 or 3 R.D.B.'s are released to confuse the escort as to the location of the attacking vessel.
 
 
 
 
        If a boat is proceeding on the surface at night and is detected by ship or plane Radar, R.D.B.'s are released and she proceeds full speed on the surface - - does not, as a rule, submerge.
 
 
 
 
QUALITY OF U-BOAT COMMANDERS DETERIORATING.
 
 
 
 
        A coxswain, who, on 19 cruises, had sailed with a number of commanders on a wide variety of missions, was pessimistic about the downward trend in competence of the current crop of U-boat captains.  While, like many others, the prisoner decried the skill of Prien, attributing much of his success to his Executive Officer, Endrass, he felt very strongly that Prien and all the old timers have learned in the only practical school.
 
 
 
 
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  The young commanders may be technically well trained and may make 1 or 2 cruises with an experienced captain but only command on active service can make then competent submariners.  Lacking this experience their judgment is unreliable.  
     
 
SAILING DAYS AT KIEL.
 
 
 
 
        Two coxswains from U-841 stated that it is the regular custom for U-boats to leave Kiel on their first patrol on Tuesdays, Thursdays and Saturdays at 0800.
 
 
 
 
U-BOAT ANCHORAGE AT HAMBURG.
 
 
 
 
When U-841 put in overnight at Hamburg in the middle of February, 1943, she tied up alongside the wharf on the east side of Tollerort just north of the point marked 10 on Map A of Hamburg in the U-boat Bases Book.  Members of the crew said it was customary for visiting U-boats to be berthed at this point, where they are covered with camouflage nets.
 
 
 
 
INCIDENT AT EL FERROL.
 
 
 
 
        A prisoner who formerly served on U-66 under Klt. Markworth stated that when U-66 was returning from the cruise on which she laid mines in the entrance to Port Castries, in late September 1942, the Chief Engineer realized that she had insufficient fuel to make Lorient.  Standing orders at that time were that the Bay of Biscay must be crossed at full speed.  The amount of oil available four days before entering Lorient was very carefully established by pumping all fuel tanks.  The Chief
 
 
 
 
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  Engineer then realized that he was short 7 to 8 tons and a signal was sent to control to this effect.  An order was then received from control to proceed to square so-and-so.  This square turned out to be the harbor of El Ferrol.  The German tanker Georg Albrecht (6-7000 tons) was anchored here, approximately 200 meters from the pier.  U-66 entered the harbor about 2300 and left again between 0330 and 0400.  Twelve tons of fuel were transferred in less than an hour by the tanker's very powerful pumps.  
     
 
        U-66 had on board a Fireman 3c (Maschinengefreiter), Helmut Ehrlichmann, who was seriously ill.  He was transferred to the tanker and he reported to the German Embassy in Madrid in civilian clothes and was sent back to Germany where he was given convalescent leave but turned up again at Lorient in time to participate in U-66's next cruise which began 9 November 1942.
 
 
 
 
        Prisoner also knew of 2 tankers, one of 10,000 tons and one of 15,000 tons, which are anchored in Vigo and frequently refuel submarines.  The crews of these tankers he believed to be civilians and given leave in Germany once a year.
 
 
 
 
PROCEDURE OF LORIENT BOATS IN BISCAY.
 
 
 
 
        See Chapter XII, Bases:  Lorient.
 
 
 
 
NOTE ON U-BOAT MORALE.
 
 
 
 
        A Warrant Machinist stated that the entire complement of a U-boat refused to take her to sea.  They were sent to the
 
 
 
 
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  military prison at Küstrin and then, presumably, to the Eastern Front.  
     
 
        Nowadays U-boat crews get little enjoyment on leave.  Even the farewell dinner before putting out to sea is a sad affair.  One informant likened it to a condemned man's last meal before his execution, as many of the complement realize that there is a good chance of never eating another meal ashore.
 
 
 
 
CAPTIVE HELICOPTERS.
 
 
 
 
        U-847 and U-848 were the first of a series of 1200-ton U-boats being constructed at the Deschimag Yards, Bremen, at about the same time as U-841.  It is reported the these and all the current 1200-ton boats are equipped with captive helicopters, a cross between a kite and a helicopter.  These helicopters are carried in three parts, in pressure-proof deck containers on platform 1 abaft the conning tower (See Plate I, Item K).  When the helicopter is assembled it is attached to a cable which unreels fro a drum in the conning tower.  The U-boat puts on maximum speed and as the helicopter rises in the wind, the pilot starts the motor, which operates a horizontally rotating screw of the "windmill" type.  (This propeller was described by the prisoners as a "Hubschraube").  The cable to which the helicopter is attached was stated to be 200 or 300 meters long.  When it is desired to bring the helicopter in, the cable was reeled in on the drum described above and the pilot steadied the helicopter by use of the propeller.  In case of emergency -pilot and helicopter would,
 
 
 
 
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  of course, be abandoned.  However, prisoners state that it was only intended to use these helicopters in remote areas of the South Atlantic and particularly the Indian Ocean.  The purpose was said to be exclusively as lookout.  While prisoners had no positive information on this use, they thought that communication between pilot and U-boat was by means of a sort of walky-talky carried on the back of the pilot.  
     
 
        Among U-boats equipped in this manner, prisoners particularly mentioned U-847 commanded by Klt. Herbert Kuppisch, and U-848 Kapitänleutnant Wilhelm Rollmann, sunk off Ascension Island 5 November 1943.
 
 
 
 
4TH AND 5TH TRAINING FLOTILLAS.
 
 
 
 
        Prisoners from U-841 confirmed the previous impression that 500-ton U-boats are attached to the 5th Flotilla in Kiel and 750-ton U-boats to the 4th Flotilla in Stettin during their Baltic trials.  Boats remain attached to their flotillas during the whole period, reporting temporarily to the other training flotillas only so long as they remain at the other training bases.
 
 
 
 
AIR PURIFICATION.
 
 
 
 
        During those periods, when U-841 remained submerged during the day she would surface for 10 minutes at 1000 and air out the boat, not surfacing again until 2100 when she would charge her batteries.  U-841 carried no new air purifying equipment.
 
 
 
 
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Click this text to view Plate J   Bergen

     
 
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CHAPTER XII - BASES
 
     
 
BERGEN.
 
 
 
 
        (Numbers refer to Map, Plate J).
 
 
 
 
        In early October 1943, U-841 and other U-boats tied up on the north side of Puddefjorden at either Dokkeskjaer Quay (1) opposite the sunken Königsberg or Möhlenpris Quay (2).  Crews were ferried across Puddefjorden to the south shore where their base (Stützpunkt) (3) was built in the foothills.  The base consisted of 10-15 barracks, a canteen and an athletic field.
 
 
 
 
        U-boat shelters at (4) were still under construction.
 
 
 
 
BREMEN. 
 
 
 
 
        The following information is as of early February 1943 when U-841 was commissioned.
 
 
 
        During the final stages of construction the crew of U-841 lived at the Lloydheim, former Merchant Marine home at the corner of Hamm and Admiral Streets near the main station.
 
 
 
        Technical ratings spent not more than one hour three times a week on board, getting most of their instructions in the class room.
 
 
 
 
        Little physical damage had been done to the Deschimag yards due to the cone of A/A fire over the yards.  Any slowing of production was due to workers sneaking out of town to escape the raids.  There were no concrete U-boat shelters.  The Seydlitz was said to be used as a personnel shelter.
 
 
 
 
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          Prisoners stated that one 750-ton and one 1200-ton U-boat were launched at Deschimag every two weeks.  (O.N.I. Note:  The following facts give lie to this statement:  the 750 tonners, U-841, U-842 and U-843 were commissioned respectively 6 February, 6 March, 3 April 1943; the 1200 tonner U-847 was commissioned about 23 January and U-848 about 20 February 1943.)  
     
 
DANZIG.
 
 
 
 
        In March 1943, U-841 did its T.E.K. (Torpedo Testing Commission) trials at Neufahrwasser in Danzig.  (O.N.I. Note:  T.E.K. had previously been reported in Gotenhafen.)
 
 
 
 
FLENSBURG.
 
 
 
 
        The commanding officer of the Torpedo School is said to be Kapitan zur See Ibbeken.  His assistant is Kapitänleutnant Hardegen, who has special charge of instructing commander pupils.
 
 
 
 
        Depot ships are the Patria and the Caribia.
 
 
 
 
GOTENHAFEN.
 
 
 
        The last of the 5-month U-boat school terms ended late in February 1942.  Up to that time engine room ratings were given instructions in both Diesels and electric motors.  Thereafter the course was shortened to three months and instructions were given in Diesels or electric motors.  At a later date the course wa again shortened, this time to six weeks, which is its present length.
 
 
 
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          All U-boat radiomen take a two-week course in underwater detection at the U.A.S. (Anti-Submarine School) in Gotenhafen.  The two or three small ships used carry K.D.B. only.  G.H.G. instruction is given in the classroom.  Barracks used are in Oxhoeft, NE of No. 6 on the Map in U-boat Bases.  
     
 
        The so called destroyers used in the Anti-Submarine School and at Tactical Exercises are converted fishing vessels and old Belgian gun boats.
 
 
 
 
HAMBURG.
 
 
 
 
        Prisoners from U-841 stated the Blohm and Voss still commissioning a 500-ton U-boat every Thursday.
 
 
 
 
HATVIK BAY.
 
 
 
 
        In late September 1943, U-841, in company with another U-boat, did listening exercises in the Bjorne Fjord at Hatvik Bay.  She left Bergen one day and returned that night.  First U-841 was listened to by a converted fishing vessel.  Then the Captain of U-841 went aboard the listening vessel while the other U-boats, 500 tonners, maneuvered under water.
 
 
 
 
        The following U-boats were attached to the base:  One large French submarine with heavy conning tower and a quadruple mounting gun, 2 Dutch boats, one Russian and one Norwegian submarine.  It was doubtful if these boats would be used again for active patrol service.
 
 
 
        There were no docks at the base, only a landing float.  Two or three Norwegian houses were used as barracks.
 
 
 
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  HELA.  
     
 
        Hela was said to be the testing ground for new and experimental types of U-boats.
 
 
 
 
        Pretactical (Vortakische) Exercises at Hela were instituted early in 1943.  From Monday through Friday each week a different group of 5 or 6 boats would exercise together with a target ship.  Exercises are directed from the depot ship Isar.  U-boat crews remained aboard during the whole period but the boats came in every night sometimes as late as 2400 and lie at anchor.
 
 
 
 
        It was said that the Swakopmund and the Preussen are the present depot ships, and that the Odin is no longer at Hela.
 
 
 
 
KIEL.
 
 
 
 
        The sequence of the piers in Kiel-Wik from North to South is as follows.  Scharnhorst, Gneisenau, York, Albatros, Iltes.
 
 
 
 
        The Torpedo Regulating Establishment is in a concrete shelter approximately 50 by 100 meters and about 100 meters from the water between the Albatros and Iltes piers.
 
 
 
        Lt. (T) Wiest (not in GNL) was said to be in command.  Obermechaniker Gabbe, 8 P.O.'s and 35 torpedomen made up the complement.  All torpedoes used in Kiel were said to be made at the Deutsche Auto Union factory and to be delivered 10 to 12 at a time.
 
 
 
        Personnel of the Torpedo Regulating Establishment are quartered on the depot ship Sierra Cordoba.
 
 
 
 
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          Depot ship Milwaukee serves as quarters for U-boat officers and midshipmen.  The depot ship New York and the old cruiser Berlin are tied up at the Tirpitz Mole.   
     
 
        The depot ship St. Louis, tied up in Wik harbor at the T-shaped pier South of (7) on the map in U-boat bases, is the headquarters of the 5th Flotilla.
 
 
 
 
        The depot ship Erwin Wassner, tied up at the Blücher Pier, houses the Personnel Bureau of the U-boat arm.  Both the St. Louis and the Erwin Wassner act as schools for radiomen who have failed in previous training.
 
 
 
 
        In late February 1943 the pressure dock lay at the Howaldt Werke.
 
 
 
 
        In the woods near the locks at Kiel is said to be a large plant in which the German Navy is carrying on secret activities, believed to be experiments with high pressure steam.
 
 
 
 
KÖNIGSBERG.
 
 
 
 
        Two years ago 80% of the yard workers were French.  There were then no ways - only repair work being done.  Now minesweepers are being built in Königsberg.
 
 
 
LORIENT.
 
 
 
        A reliable Petty Officer stated that in August 1943 the 2nd Flotilla lost 18 U-boats and the 10th Flotilla 22 U-boats, a total of 40 for the month for the base.
 
 
 
 
        The same Petty Officer who had been on a number of southern patrols gave the following information as of February 1943:
 
 
 
 
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          U-boats left Lorient on a course of 1800.  Up to 90 miles from Lorient boats were forbidden to submerge.  After leaving the 90 mile zone South bound U-boats steered a direct course for Cape Finisterre.  They again passed Finisterre on the way in - steering first a course of 230 and then a course of 580.  On passing 150 West on the way out the ships always made a signal to control.  Luzie I was said to be the point for meeting escorts on the way in and out of Lorient.  After passing Luzie II, tactics were to submerge by day, and surface by night four or five hours.  A returning boat would send its first signal from the Azores area and another one at dusk just before reaching the 90 mile line.  This line was crossed only in daylight.  
     
 
PILLAU.
 
 
 
 
        Kapitänleutnant (I,g.) Wessels, Ex-Engineer Officer Prien at Scapa Flow is now an instructor at Pillau.
 
 
 
 
SWINEMÜNDE.
 
 
 
 
        In the fall of 1942 the Gun Layer (Geschützfuhrer) course lasted 6 weeks; 3 weeks of theoretical training at Sassnitz were followed by 3 weeks of practical instruction at Swinemünde.  Trainees lived in barracks at Sassnitz and on the depot ship General Osorio at Swinemünde.
 
 
 
 
        At the same time the A/A course lasted 5 weeks.  Trainees were said to live in the school ship Nahsa while out on exercises.  (O.N.I. Note:  Gunnery School Ship Mars is probably meant.)
 
 
 
 
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Click this text to view Plate K   Trondheim

     
 
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          In the summer of 1943, 4 to 5 U-boats were doing A/A Gunnery practice at Swinemünde together.  For two or three days they would shoot at sleeve targets, every man on board including cooks and doctors taking active part in the exercises.  
     
 
STETTIN.
 
 
 
 
        A prisoner who was stationed at Stettin from June 1941 to March 1943 stated that in that time one or two U-boats would be on the ways at the Oderwerke but that he never saw a U-boat launched there in this period.  He stated that U-boats always took on supplies at the north end of Tirpitz Island, near the depot ship Usambara.
 
 
 
 
TRONDHEIM.
 
 
 
 
        Numbers refer to map, Plate K)
 
 
 
 
        U-841 lay in the U-boat shelters (1).  Prisoners stated that 3 of the five pens would hold two boats each; the remaining pens, three boats each.  All pens, it was stated, could be pumped dry.  The design of the shelters followed the usual pattern - the Torpedo Regulating Establishment was at (3)
 
 
 
 
        Officers and crew lived at the Base, known as the Priengelände, above the runway and near the radio tower (4).  There were said to be 22 numbered barracks, a canteen and an athletic field.
 
 
 
        Reliable petty officers stated that the 13th Flotilla had been based at Trondheim since late in 1942.  The first Flotilla Commander, a Kapitan zur See, was succeeded sometime
 
 
 
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  in June 1943 by Korvettenkapitän Rolf Rüggeberg.  His assistant is reported to be Siemon.  (O.N.I. Note:  Kapitänleutnant Hilmar Siemon of the 1934 term.)  
     
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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CHAPTER XIII.  OTHER U-BOATS
 
     
 
U-66         A prisoner who had served on this U-boat while under the command of Kapitänleutnant Zapp, as well as his successor Kapitänleutnant Markworth, stated that in July 1942 six torpedo mines were laid outside of Port Castries, Santa Lucia.
 
        On this patrol, torpedoes and mines were distributed as follows:
 
                4 torpedoes in bow tubes
 
                4 torpedoes under floor plates in forward torpedo compartment
 
                6 mines above floor plates in forward torpedo compartment
 
                2 torpedoes in stern tubes
 
                3 torpedoes above floor plates in stern torpedo compartment
 
                6 torpedoes in upper deck containers.
 
        This prisoner believed the mines carried to be type T.M.B. (magnetic).  While at sea torpedoes were removed from the forward tubes and three mines were loaded into each tube.  (O.N.I. Note:  On 29 July 1942 a U.S.C.G. motor launch was damaged at Port Castries by an under water explosion.  On 2 August 1942 a British M.T.B. was damaged by a mine explosion.
 
         On that same date two mines were swept.  Efforts being made now to recover the remaining two mines.  It is known that these mines are acoustic mines.)
 
 
 
 
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U-105         In the Summer of 1942, U-105 then under the command of Korvettenkapitän Schuch, was reported to have put into El Ferrol, Spain, for repairs to damage caused by an aircraft attack.  After about two weeks she proceeded to her base at Lorient where she exchanged crews with U-156, commanded by Kapitänleutnant Hartenstein.  (O.N.I. Note:  U-156 is known to have been sunk early in 1943).
 
U-106         Prisoners confirmed that early in 1942 the entire bridge watch was washed overboard in heavy seas.  The disappearance of the watch was said to have gone unnoticed for two hours.
 
U-108         Reported to have sunk 368,000 tons of shipping.
 
U-109         Stated to belong to the 2nd Flotilla at Lorient.  Previous information that U-109 had been attached to the 3rd Flotilla at St. Nazaire is probably incorrect.
 
U-141         Upon completion of her fourth patrol U-141 was taken back to Germany by Kapitänleutnant Schüler and was believed to have been decommissioned on her arrival there.  (O.N.I. Note:  This took place probably late 1942).
 
        U-141's officers at that time were reported to have been:
 
                Commander - Kapitänleutnant Phillip Schüler.
 
                Executive Officer - Oberleutnant zur See Heydemann.  (O.N.I. Note:  Not known which of the Heydemanns).
 
                Second Watch Officer - Leutnant Helmut Kruger.  (O.N.I. Note:  Krugger was apparently transferred to U-591, also as Second
 
 
 
 
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Watch Officer but left her in April, 1943 after two patrols.)
 
        Schüler was stated to have taken over a new 500 ton U-boat and transferred to her part of U-141's crew.  It was reported that Schüler was lost in the Mediterranean August or September, 1943.  (O.N.I. Note:  Schüler was believed to have commanded U-602, reported lost in April, 1943.)
 
U-157         Her commander was reported to have been Korvettenkapitän Henne.  (O.N.I. Note:  Henne is known to have been a casualty since early 1942.  This may indicate U-157 was lost at that time.)
 
U-159         Reported to have left Kiel on her first patrol in March 1942.  After what proved to be an uneventful passage she was to put in to Lorient, but was ordered into St. Nazaire from where, after two days, she proceeded to Brest.  U-159 and three or four other U-boats made several short patrols of from 8 to 13 days in the Bay of Biscay.  At the end of April 1942 U-159 put into Lorient from where she left in May 1942 in company with U-68.  Her operational area was the Caribbean.  On the way she claimed to have sunk several ships in the vicinity of the Azores and some stragglers from a Caribbean convoy.  On her return trip U-159 sustained some damage in an unidentified attack but was able to make Lorient some time in June or July 1942.
 
U-161         Reported to be a schoolboat at Gotenhafen.
 
U-170         Reported to be at Lorient in February 1943.  (O.N.I. Note:  This confirms previous information that U-170 was not mined or
 
 
 
 
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sunk in the Bay of Biscay in October 1942.)
 
U-198         Prisoners from U-841 believed that U-198, under Werner Hartmann was lost.  The armament of U-198 was stated to have included a clip-fed 37 mm. gun.  (O.N.I. Note:  Hartmann was recently reported lost late October 1943.  However, another source indicated that Kapitän Hartmann spoke over the radio on 14 October 1943.  It is possible that Hartmann was saved after his U-boat sank.)
 
U-212         Believed to have rammed and sunk a British destroyer which had previously depth-charged her.  U-212 made port, her bow crumpled.  (O.N.I. Note:  Other sources indicate that this may have happened late July or early August 1943.)
 
U-231         Believed to operate in the Arctic.
 
U-232        Stated to be a 500 ton U-boat built at Vegesak and commissioned late in 1942.  She was said to have left Trondheim during the latter part of September 1943 and to have returned about two weeks later with her 20 mm. quadruple mount damaged while attempting to surface under an iceberg.  She was reported to be attached to the 13th Flotilla at Trondheim.
 
U-251         Believed to be attached to the 13th Flotilla at Trondheim.
 
U-302         Formerly commanded by Kapitänleutnant Achilles, is now under Kapitänleutnant Herbert Sickel, of the 1936 term.  U-302 is stated to be a 500 ton boat, type VII C.  She was painted white.
 
        It was reported that U-302, which is believed to be
 
 
 
 
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attached to the 13th Flotilla at Trondheim returned to Trondheim about 1 October 1943 after a five week patrol.
 
U-541         Stated to have been on tactical exercises in the Baltic 1-10 May 1943.
 
U-563         A prisoner stated that U-563 had been a member of the "Gruppe Schlieffen".  U-841 intercepted the following radio messages from a U-boat believed to be U-563:
 
        1.  Two men overboard.
        2.  Being attacked by two-motored bomber; am continuing to fight.
        3.  This is the end.
 
        U-563 was believed to have been sunk on or about 17 October 1943.  (O.N.I. Note:  In the area southeast of Greenland, 3 U-boats were claimed sunk by aircraft on 16 October; on 17 October one U-boat was claimed sunk by surface craft and one by aircraft.  One of these was U-841.)
 
U-506         Said to be attached to the 13th Flotilla.
 
U-622         This U-boat was believed to have been sunk during an air raid on Trondheim, but her crew saved.  She had been attached to the 13th Flotilla.  (O.N.I. Note:  U-622 had previously been reported lost in the North Atlantic late 1942.  This contradicts the statement that she belonged to the 13th Flotilla, which was not in Trondheim until 1943.)
 
U-625         Her commander was stated to be Hans Benker, of the 1936 term.  U-625 was said to have laid mines near Murmansk in the Summer of 1943.
 
 
 
 
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U-642         Stated to have been commissioned 25 August 1942.  Believed to have left on her first patrol on 17 February 1943.  Her commander was confirmed to be Kapitänleutnant Brünning.
 
U-812         Stated to have operated in "Gruppe Schlieffen" together with U-841 and other boats.
 
U-842         Stated to be a 750-ton boat, Type IX c built at Deschimag, Bremen.  She was commissioned 6 March 1943.  Her commander is Kapitänleutnant Heller of the 1930 term.  U-842 probably was a member of "Gruppe Schliffen".  U-841 intercepted a signal from U-842 that she had been subjected to s depth charge attack.
 
U-843         Reported to be a 750-ton boat, Type IX C built at Deschimag, Bremen.  Her commissioning date was give as 3 April 1943.
 
U-844       Reported to be a 750-ton boat, Type IX C built at Deschimag, Bremen and commissioned 1 May 1943.  She was a member of the "Gruppe Schlieffen", possibly contact keeper at one time, and was reported sunk on or about 17 October 1943.  (O.N.I. Note:  In the area southeast of Greenland, 3 U-boats were claimed sunk by aircraft on 16 October; on 17 October one U-boat was claimed sunk by surface craft and one by aircraft.  One of these was U-841.)
 
U-845         Stated to be a 750-ton boat.  Type IX C, built at Deschimag, Bremen.
 
U-846         Stated to be a 750-ton boat, Type IX C built at Deschimag, Bremen.
 
 
 
 
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U-847         First of a series of 1200-ton U-boats built at Deschimag, Bremen.  Commissioned about 23 January 1943 and equipped with a captive helicopter. On Active Service Training group tests conducted about same time as U-841, April 1943.
 
        Her first commander was stated to have been Kapitänleutnant Friedrich Guggenberger who previously had commanded U-81.  During a practice shooting with a machine gun, Type MG-15, two men were killed and an ensign wounded.  Possibly this accounted for the transfer of Guggenberger from U-847 to U-513.  (O.N.I. Note:  Guggenberger was taken prisoner at the sinking of U-513 19 July 1943.)
 
        Korvettenkapitän Josef Metzler succeeded Guggenberger in command of U-847 but was detached some time during the Baltic trials, due to stomach disorder.  During his command a man was decapitated by the propeller of the captive helicopter.
 
        The third commander of U-847 was reported to be Kapitänleutnant Herbert Kuppisch, under whom the boat completed her trials.  It was believed that she had sailed for Japan and had arrived safely.
 
U-964         On tactical exercises with U-841 and believed to have been one of the contact keepers for "Gruppe Schlieffen".  U-841 intercepted a signal from U-964 in which it was stated that she was being attacked by aircraft.  Thereafter no further signals were received and it was believed that she was sunk on 17 October 1943.  Four survivors were believed to have been rescued by another U-boat.  (O.N.I. Note:
 
 
 
 
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  In the area southwest of Greenland, 3 U-boats were claimed sunk by aircraft on 16 October; on 17 October one U-boat was claimed sunk by surface craft and one by aircraft.  One of these was U-841.)
 
     
 
U-BOAT OFFICERS
 
 
 
 
BURGHAGEN         Reported to be commander of a 1600-ton U-boat which underwent test of the Active Service Group at the same time as U-841.  She may have been the boat which left Kiel on 26 August 1943 together with U-841; her operational area was believed to have been the Indian Ocean. Her insignia was in the shape of a pennant, the top half of which was white, the lower half green.  Three sitting rabbits on pennant.
 
HARDEGEN         Reported to have been the commander of the Torpedo School at Flensburg in the Summer 1943.  He is not well physically.
 
HEILMANN         A prisoner stated that an officer with a name similar to Heilmann commanded a 500-ton U-boat, possibly U-309 or U-389.  (O.N.I. Note:  This may refer to Kapitänleutnant Udo Heilmann of the 1933 term who was reported to have had a 500-ton U-boat after U-97 and later taken over a 750-tonner.
 
HEPP         A U-boat under command of Kapitänleutnant Hepp was seen at Trondheim mid-September 1943.  The number of the boat
 
 
 
 
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might possibly be U-309 or U-389.
 
KELLER         Keller was reported to have been commander of a 750-ton U-boat which was sunk.  Keller was a casualty at the sinking.  (O.N.I. Note:  This probably refers to Oberleutnant Siegfried Keller of the 1937 A term who had been reported a casualty early 1943.)
 
MÖLLER         A 500-ton U-boat commanded by a Möller participated in some parts of U-841's trials in the Baltic in the Spring of 1943.  (O.N.I. Note:  This may have been Oberleutnant Günther Möller of the 1937 A term who had previously been reported as commander of a new U-boat in the Spring of 1943.)  It is possible that U-Möller also was a member of "Gruppe Schlieffen".
 
PIETSCH         Kapitänleutnant Ulrich Pietsch was stated to be a commander of a 500-ton U-boat.
 
WIEDEMEYER         Believed to command a 1600-ton U-boat.  He had previously served as executive officer on U-66.  In Summer 1942 he was at the Torpedo School at Flensburg and later made a patrol as student commander under instruction.  He was said to be nervous and unreliable.
 
 
 
 
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ANNEX.  CREW LIST OF U-841 AND U.S. EQUIVALENTS
 
                                            OF GERMAN NAVAL RANKS  
 
 
 
  Name Rank USN Equivalent Age
         
    Kapitan z. S. Captain  
    Fregattenkapitän Commander  
    Korvettenkapitän Lt. Commander  
* Bender, Werner Kapitänleutnant Lieutenant 25
* Bräutigam, Dr. Rudolf Marinestabsarzt Lieutenant (MC) 28
* Hörig, Max Oberleutnant (Ing.) Lieutenant 35
  Knaup, Herman Leutnant z. S. Ensign 23
* Nahrgang, Norbert Oberfähnrich z. S. Midshipman 23
* Stueber, Walther Obersteuermann Warrant Quartermaster 35
* Salaske, Paul Oberbootsmann Boatswain 28
* Hedtfeld, Willi Obermaschinist Warrant Machinist 33
  Schwerin, Gerhard Obermaschinist Warrant Machinist 29
  Schnare, Heinz Bootsmaat Coxswain 21
  Trautes, Willi Bootsmaat Coxswain 22
* Reil, Hans Funkmaat Radioman 3c 24
* Schonfeld, Helmut Mechanikersmaat Torpedoman's mate 3c 22
  Debus, Heinz Maschinenmaat Fireman 1c 23
  Elke, Berthold Maschinenmaat Fireman 1c 24
* Fochem, Karl Maschinenmaat Fireman 1c 24
* Peulecke, Heinz Maschinenmaat Fireman 1c 23
* Rokitta, Otto Maschinenmaat Fireman 1c 23
* Springer, Rudi Maschinenmaat Fireman 1c 22
* Wald, Heinrich Maschinenmaat Fireman 1c 24
  Helfrich, Erich Matrosenobergefreiter Seaman 1cl 20
* Rydzick, Willi Matrosenobergefreiter Seaman 1cl 21
* Welsch, Horst Matrosenobergefreiter Seaman 1cl 21
* Charrier, Hans Funkhauptgefreiter Seaman 1cl 24
  Boehme, Heinz Funkobergefreiter Seaman 1cl 22
* Gischowski, Kurt Maschinenobergefreiter Fireman 2c 23
  Honer, Kurt Maschinenobergefreiter Fireman 2c 23
* Jung, Gregor Maschinenobergefreiter Fireman 2c 21
* Kundtner, Karl Maschinenobergefreiter Fireman 2c 20
* Kunert, Herbart Maschinenobergefreiter Fireman 2c 22
  Stichling, Walther Maschinenobergefreiter Fireman 2c ?
  Thorausch, Rudolf Maschinenobergefreiter Fireman 2c 20
  Witt, Horst Maschinenobergefreiter Fireman 2c 19
  Bochenek, Alois Matrosengefreiter Seaman 2c 21
* Jennoch, Heinz Matrosengefreiter Seaman 2c 21
  Liedke, Wilhelm Matrosengefreiter Seaman 2c  
* Rosenthal, Kurt Matrosengefreiter Seaman 2c 18
  Smarz, Albin Matrosengefreiter Seaman 2c  
  Schweigebauer, Rudolf Matrosengefreiter Seaman 2c 22
* Snella, Werner Matrosengefreiter Seaman 2c 19
  Taubert, Heinz Matrosengefreiter Seaman 2c 20
  Voss, Franz Peter Matrosengefreiter Seaman 2c 23
 
 
 
 
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  Name Rank USN Equivalent Age
         
* Weissenhorn, Rudi Matrosengefreiter Seaman 2c 19
  Brendel, Rudolf Funkgefreiter Seaman 2c 21
  Doeller, Kurt Mechanikergefreiter Seaman 2c 19
  Gunther, Reinhard Mechanikergefreiter Seaman 2c 19
* Ostertag, Albert Mechanikergefreiter Seaman 2c 21
  Weber, Karl Mechanikergefreiter (A) Seaman 2c 19
  Eder, Richard Maschinengefreiter Fireman 3c 20
  Kötting, Gustav Maschinengefreiter Fireman 3c  
* Krüger, Otto Maschinengefreiter Fireman 3c 20
  Placowsky, Hermann Maschinengefreiter Fireman 3c  
  Ratius, Bernhard Maschinengefreiter Fireman 3c  
  Rothenburg, Heinz Maschinengefreiter Fireman 3c  
 
     
 
*  Denotes Casualty (Ages of casualties approximate)
 
 
 
 
d.R.   Denotes reserve officer.
 
 
(Ing.) Denotes engineering duties only.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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