Re-assessment of German U-boat losses in World War II
The loss of U 305, U 377 and U 641
by Dr. Axel Niestlé
(All Times are Central European Time (GMT + 1))
24 September 2003
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U 305 (Kapitänleutnant Rudolf Bahr) left Brest in France on 8 December 1943 for its fourth patrol in the North Atlantic. At 1424 on 18 December 1943 U-boat Command directed the boat to join the newly formed group Borkum stationed to the west of Spain across the convoy route between Britain and Gibraltar. After conducting operations against various Allied convoys and A/S groups passing through its operational area during the following weeks, group Borkum was finally dissolved on 13 January 1944. At 1332 on the same day U 305 was attributed to group Rügen, then operating to the west of Britain in a loose formation across the North Atlantic convoy routes. Together with other ex-Borkum boats U 305 was to extend the patrol line towards the south. Its new operational area covered a radius of 30 nautical miles around naval grid square BE 2859. By the same signal U 305 was ordered to change to 'Irland' radio service as from 0800 on 14 January. Following a request by U-boat Command at 2206/14 U 305 radioed in its last known signal at 0827 on 15 January that the boat intended to commence its return to France on 20 January 1944. At 1224 on 2 February U-boat Command ordered the boat to report at once. When no answer was received and the boat also failed to arrive in port, U 305 was posted as missing on 3 February 1944 with effect from 2 February 1944 during the return passage to France.
After the war the Allied Assessment Committee attributed the loss of U 305 to the attack of the destroyer HMS Wanderer and the frigate HMS Glenarm on 17 January 1944 in position 49°39´n/20°10´w. The two ships were part of the escort group B1 homebound after having searched for German blockade-runners. At 1355 Wanderer sighted a U-boat on the surface and was sent to attack together with Glenarm. The U-boat dived, but Wanderer picked up asdic contact at 1200 yards and dropped a five-charge pattern at 1400 that probably missed ahead. At 1409 the destroyer carried out an unsuccessful Hedgehog attack. In a third attack Wanderer dropped ten depth charges with no apparent result. Following a hedgehog attack by Glenarm at 1546 the two ships carried out four more unsuccessful attacks. At 2045 good contact was established and at 2056 Wanderer carried out another Hedgehog attack, which resulted in a single underwater explosion 15 seconds after launching, believed to have indicated a direct hit on the target. Thereafter contact was lost. Despite a search by all four ships of B1 group no further evidence of destruction could be found before the search was finally abandoned at 0117 on the next day. However, based on the available evidence the Admiralty graded the attack as "B - believed sunk". When post-war analysis of German records revealed the loss of U 305 at about this time in the general area of the attack, its loss was eventually attributed to this attack.
In attributing the loss of U 305 the Committee obviously ignored the fact that the attack took place well out of the operational area assigned to U 305. The distance between the location of attack and the naval grid square BE 2859 as the centre of the boats operational area is about 75 nautical miles, thus exceeding the operational radius at least by the factor 2.5 in northwestern direction. Although U-boat Command had encouraged boats to exploit every chance for attack, it is considered unlikely that U 305 had left its assigned operational area without notifying control about it. This supports the conclusion that the attack was very probably not directed against U 305 and consequently HMS Wanderer and HMS Glenarm can no longer be attributed with the loss of U 305. However, there were two other boats operating in the general area, which also did not return from patrol.
U 377 (Kapitänleutnant Gerhard Kluth) had left Brest into the North Atlantic on 15 December 1943 for its twelfth operational patrol. On 23 December 1943 U-boat Command directed the boat to join group Borkum stationed to the west of Spain across the convoy route between Britain and Gibraltar. After conducting operations against various Allied convoys and A/S groups passing through its operational area during the following weeks, group Borkum was finally dissolved on 13 January 1944. At 1232 on the same day U 377 was attributed to group Rügen, then operating to the west of Britain in a loose formation across the North Atlantic convoy routes. Together with other ex-Borkum boats U 377 was to extend the patrol line towards the south. Its new operational area covered a radius of 30 nautical miles around naval grid square BE 2144. By the same signal U 377 was ordered to change to 'Irland' radio service as from 0800 on 14 January. At 2206 on 14 January group Rügen was partly rearranged with U 377 now assigned to naval grid square AL 9798. U-boat Command advised the boats to use economical speed and to move submerged during daylight. At 1605 on 19 January group Rügen was again ordered to shift into new positions by 1900 on the next day with U 377 assigned to AM 4777. The operational radius was now reduced to 20 nautical miles. After unsuccessful operations group Rügen was eventually dissolved on 26 January and at 1958 on the same day U 377 was reassigned to the newly formed group Hinein. This group, consisting of eight boats, was ordered to form a patrol line from 1730 on 27 January stretching from AM 7132 to AM 7628. U 377 was to occupy the position AM 7259. U 377 reported last at 0404 on 15 January 1944 from square BE 5748 about two attacks with homing torpedoes against an unidentified search group, claiming to have heard a heavy explosion after 9 minutes following the second shot without being depth charged thereafter. U-boat Command plotted the boat to have commenced its return trip to France on or about 29 January 1944. When U 377 thereafter failed to enter La Pallice as the newly assigned port of arrival by 10 February 1944, U 377 was posted as missing the same day with effect from 4 February 1944. In the absence of any information about its fate, U-boat Command considered the possibility that U 377 was already lost in January 1944 during operations with groups Rügen or Hinein.
After the war the Allied Assessment Committee nevertheless felt unable to attribute the loss of U 377 to any known A/S-attack carried out in the eastern North Atlantic or the Bay of Biscay during the period when the boat supposedly disappeared. Therefore the loss of U 377 remained unexplained and the boat was officially recorded as 'lost to unknown cause'.
U 641 (Kapitänleutnant Horst Rendtel) had left St. Nazaire in France on 11 December 1943 for its fourth patrol in the North Atlantic. At 1424 on 18 December 1943 U-boat Command directed the boat to join the newly formed group Borkum stationed to the west of Spain across the convoy route between Britain and Gibraltar. After conducting operations against various Allied convoys and A/S groups passing through its operational area during the following weeks, group Borkum was finally dissolved on 13 January 1944. At 1232 on the same day U 641 was attributed to the group Rügen, then operating to the west of Britain in a loose formation across the North Atlantic convoy routes. Together with other ex-Borkum boats U 641 was to extend the patrol line towards the south. Its new operational area covered a radius of 30 nautical miles around naval grid square BE 2515. By the same signal U 641 was ordered to change to 'Irland' radio service as from 0800 on 14 January. Following a request by U-boat Command at 2206/14 U 641 radioed in its last known signal at 0318 on 15 January that the boat intended to commence its return to France on 20 January 1944. When the boat thereafter failed to arrive in port by 2 February 1944, U-boat Command ordered the boat at 1215 on the same day to report its position forthwith. In the absence of any reply U 641 was posted as missing on 3 February with effect from 2 February 1944.
After the war the Allied Assessment Committee attributed the loss of U 641 to the attack of the corvette HMS Violet on 19 January 1944 in position 50°25´n/18°49´w. The corvette was part of the escort group B3 escorting the outbound convoy OS 65/KMS.39 on its way to Gibraltar. At 1901 Violet located U 641 three miles behind the convoy. The radar operator picked up a signal on the surface and later confirmed it as a U-boat. Violet altered course, headed for the U-boat and reduced speed to 5 knots. With the contact still on the surface, it was decided to ram the U-boat if the corvette could get close enough. Apparently the corvette was observed by the U-boat as it crash dived at the time when Violet fired one round from her four inch gun. Thereafter the boat was picked up by the asdic operator. Slow speed was maintained as the contact was heard turning away under the prevailing favourable asdic conditions. Shortly afterwards a Hedgehog attack ware carried out and after an interval of sixteen seconds two, almost simultaneous, explosions were heard. A third followed two seconds later, indicating that three of the 24 projectiles had hit. At 1935 an oil patch was observed and three minutes later a second Hedgehog attack was carried out. After passing over the contact a violent muffled explosion was heard, later followed by breaking up noises. On searching the area strong smell of diesel oil and an oil patch covering an area of one by one-and-a -half cables was observed. However, efforts to obtain a sample of it failed in the prevailing heavy sea. Based on the available evidence the attack was graded "B - believed sunk". When post-war analysis of German records revealed the loss of U 641 at about this time in the general area of the attack, its loss was eventually attributed to this attack.
According to the available information the losses of U 305, U 377 and U 641 must have occurred to the west of or in the Bay of Biscay at some time between the 14th January and 4th February 1944 at latest. During this time span the following anti-submarine attacks including those already mentioned above, took place along the assumed routes of the three boats:
|1455/17||HMS Wanderer & HMS Glenarm||49°39'N / 20°10'W||D/C B||U ? sunk|
|2001/19||HMS Violet||50°25'N / 18°49'W||D/C B||U ? sunk|
|0130/19||HMS Northern Sky||48°25'N / 18°07'W||D/C H||U ? / non-sub?|
|1223/25||HMS Versatile & HMS Vidette||51°22'N / 18°24'W||D/C G||U ? / non-sub?|
|1239/26||HMS Essington||53°47'N / 11°17'W||D/C H||U ? / non-sub?|
|1247/28||Liberator E/VB-103 USN||53°15'N / 15°52'W||D/C B||U 271 sunk|
|1303/28||Sunderland D/461 RAAF||52°41'N / 14°27'W||D/C B||U 571 sunk|
|0033/29||Wellington G/304 RAF||47°00'N / 05°38'W||D/C G||U 471 no damage|
|0300/29||Wellington R/172 RAF||47°03'N / 05°20'W||D/C G||U 471 no damage|
|0403/29||Halifax S/502 RAF||46°56'N / 05°04'W||D/C F||U 471 no damage|
|1332/29||Liberator N/VB-110 USN||51°07'N / 16°19'W||D/C G||U 592 damaged|
|2107/29||Halifax U/502 RAF||45°33'N / 05°55'W||D/C F||U 364 sunk|
|0215/30||Halifax L/502 RAF||47°33'N / 06°24'W||D/C F||UJ 1405, UJ 1415 no damage|
|1215/31||HMS Starling & HMS Wildgoose, HMS Magpie||50°20'N / 17°29'W||D/C A||U 592 sunk|
Map of the attacks in question:
Details about the attacks not yet attributed to an individual U-boat are unavailable but based on the war-time assessments it is unlikely that any of these attacks resulted in the destruction of a U-boat. It should be noted that the two attacks graded "H" gave insufficient evidence for the presence of a submarine, whereas the third attack was considered unable to have caused any damage to the submarine believed to have been present.
In addition to the Allied attacks mentioned above two partly corrupt war emergency reports obviously originating from German U-boats were monitored by German and Allied radio stations. At first a corrupt signal was received at 0539 on 16 January on 'Diana' service, stating 'torpedo hit, boat seriously damaged, is sinking, can only be held for a short time'. Unfortunately, information on the position and the signature was corrupt and could not be decrypted. At 0814 on 19 January another war emergency report was received corrupt in the 54-metre band, stating 'torpedo hit, confidential documents destroyed. Boat seriously damaged, is sinking. Can only hold her own for a short time now'. Again the square position was unclear and the signature remained unknown as the signal strength diminished rapidly at the end of the signal.
From the description of the results achieved in all attacks graded "A" or "B" during the time span under review there can be no doubt that all five U-boats could be considered sunk or seriously damaged. By plotting the most likely positions reached by U 305, U 377 and U 641 at the various times of attack, it is most probable that the attack by HMS Violet on 19 January 1944 was in fact directed against U 641 which should have stayed around square BE 2515 at that time. The distance towards the position of attack is only 30 nautical miles in northerly direction, disregarding possible navigational errors. Thus the location of the sinking is on the edge of the operational area assigned to U 641 at that time. U 305 should have stayed at least about 75 nautical miles to the south and U 377 is expected to have already passed some 24 hours earlier to the west of the position enroute to its attacking area in square AL 9798. Thus the decision of the Assessment Committee on the loss of U 641 is found to be correct.
Using U 377's last report at 0814 on 15 January 1944 from square BE 5748 as a reference, the attack of HMS Wanderer and HMS Glenarm two days later took place almost exactly on the boats direct course line towards the centre of its assigned attacking area around square AL 9798. The remaining distance between its last known position and the location of the attack is about 220 nautical miles, which equals the boat's mileage to be expected under the prevailing conditions and the given order to use economical speed. Thus it is very probable that it was in fact U 377 that was sunk by the two ships on 17 January.
The text of the two war emergency signals monitored on 16 and 19 January leaves no doubt that a U-boat was probably involved in both cases. Both signals appear also in British 'Ultra' documents, which make it unlikely to have been a fake signal sent by Allied radio stations. It is however significant that the wording of both signal is very similar. There can be no doubt that a U-boat is unlikely to survive a torpedo hit. Therefore both boats must be considered as sunk providing the two signals are genuine. Taking the loss of U 377 and U 641 as being given above, the only alternative for the boat reportedly hit early on the 16 January is U 305 as all other boats then at sea and lost afterwards reported at least once thereafter without mentioning the incident.
The originator of the second signal on 19 January remains yet unclear. The only possibility for this incident is U 571 which reported last at 1830 on 18 January about an encounter with a small westbound convoy in AL 9843 during which it had fired a T-5 on a destroyer followed by a torpedo explosion ten minutes later. U 571 was later assigned to groups Rügen and Hinein. Presently U 571 is however believed sunk during its operation against convoy ON.221 on 28 January. Although in the past some sources attributed the loss of U 972 to one of the torpedo incidents, this is not supported by the historical facts. It is highly unlikely that U 972, which reported last on 15 December 1943, carried on for over one month without signalling. Even in the case of a receiver breakdown in its radio station it would have been reasonable to expect that the boat had met with one of its group neighbours in the meantime to inform U-boat Command about the situation
Based on the information presented above it is proposed to amend the records to show that:
U 305 was lost with all hands on 16 January 1944 probably to one of its own torpedoes in the approximate position 49°n/18°w.
U 377 was lost with all hands on 17 January 1944 in the attack of HMS Wanderer and HMS Glenarm in position 49°39n/20°10w
Dr. Axel Niestlé
This article was published on 23 Dec 2004.