The loss of U 325, U 400 and U 1021 Re-assessment of German U-boat losses in World War II

Wreck No 1 rests in the southern half of field “HY A1”, laid by Plover on 12 December 1944. Consisting of 100 Mk XVII (39)/XVII units, it spread along a line extending for 3.3 miles in direction 171° from position 50°42.5N, 05°05.4W at a depth of 70 feet. Two surface failures were reported during laying.

Wreck No 2 is situated in the southern half of field “HW A3”, laid by Apollo between 0131 and 0156 on 3 December 1944. Consisting of 156 Mk XVII (39)/XVII units, it spread along a line extending for five miles in direction 182.5° from position 50°36.7N, 05°11.1W at a depth of 70 feet. One possible failure was observed during laying.

Wreck No 3 lays on the southern end of field “HW A1”, laid by Apollo between 0131 and 0156 on 29 November 1944. Consisting of 156 Mk XVII (39)/XVII units, it spread along a line extending for five miles in direction 179° from position 50°34.5N, 05°23.0W at a depth of 70 feet.

From the evidence reported above it is beyond all doubt that all three U-boat were in fact lost to secretly laid allied minefields, which had remained unknown to German U-boat Command for the duration of the war.

Apart from the presence of the three wrecks, no direct information on their identity was found. However, detailed underwater examination of the wrecks by the diver Innes McCartney revealed numerous design and equipment features. Comparison of these individual features with available information on the contemporary outfit of the three boats in question by the author eventually allowed to conclude on the most likely identity of the three wrecks. Accordingly, wreck No 1 should be U 400, wreck No 2 should be U 1021 and wreck No 3 in all likelihood should be U 325. The assessment is mainly based on the following conclusions:

Wreck No 1 is fitted with the old Type 1 folding schnorkel installation with half-height pressure flange connection to the diesel air intake tube along the port side of the conning-tower casing in combination with a ring-float schnorkel valve with Wesch-type anti-radar coating on the circular stem tube between the exhaust outlet and the ring-float head. No anti-radar coating is found on the drum-shaped ring-float head. The circular foundation plate for a deck gun originally installed on Type VIIC boats is clearly in place in front of the conning-tower, forward to the rectangular hatch covering the former ready-for-use ammunition space. In addition, the gun mount of the 3.7 cm AA gun now lying on top of the wreck closely resembles the late-war Type LM43U gun mount. U 400 was fitted with one of the first such mounts for frontline testing. While U 1021 is known to have been fitted with a ball-float schnorkel head, U 325 is recorded to have carried the Jaumann-type anti-radar coating on its ring-float type schnorkel head. In addition, U 325 was never fitted with the deck gun foundation plate. Based on this evidence, it is concluded that the identity of the wreck No 1 should be that of U 400. According U-boat Command’s daily plot, U 400 was expected to arrive in its operational area on or shortly after 14 December 1944. Thus it is entirely plausible that U 400 met its end only days after laying of the new A/S minefield.

Wreck No 2 is fitted with the old Type 1 schnorkel installation with ball-float schnorkel valve, Wesch-type anti-radar coating on the schnorkel head and four pressure-proof dinghy containers on the forward deck. Except U 1021 none of the other two boats in question carried this combination of features on its final patrol. On the basis of the average speed of advance then attained by Type VIIC schnorkel boats, U 1021 is expected to have arrived in its operational area on or about 10 March 1945. That appears to coincide with the sighting of a suspected periscope on the afternoon of 10 March 1945 by the minesweeping trawlers HMS Concertator and HMS Lorraine in position 50°36’N, 05°15’W. The trawlers carried out an attack, during which they expended their full outfit of eight depth charges, without result. On the afternoon of 14 March 1945 the British steamer Rolfsborg, a straggler from convoy TBC 95, heard a heavy explosion when in 294° Trevose Head 4 miles, which converts to approximately 50°34’N, 05°07’W, and observed patches of oil. At the time of the incident there were no other surface vessels in the area. In the light of this evidence it is possible that U 1021 was lost on this occasion due to mining.

Wreck No 3 is badly corroded but none of the features found on it opposes to the outfit of U 325 to be expected on its last patrol. From the fact that U 325 passed a transit report from the area west of Ireland and the absence of any promising A/S attacks along its expected route or in its assigned operational area, it is most likely that U 325 arrived off the Cornish coast. U 325 is expected to have arrived in its assigned operational area on or about 17 April 1945. For reason of completeness it should be mentioned that in the time-span between mid-April 1945 and VE-day the following attacks by aircraft and escort ships took place near the wreck position: