|Ordered||15 Aug 1940|
|Laid down||1 Jul 1941||Blohm & Voss, Hamburg (werk 597)|
|Launched||19 Mar 1942|
|Commissioned||7 May 1942||Kptlt. Horst Schünemann|
|Successes||4 ships sunk, total tonnage 20,159 GRT|
1 auxiliary warship sunk, total tonnage 2,938 GRT
1 ship damaged, total tonnage 10,048 GRT
1 warship damaged, total tonnage 1,625 tons
Sunk 18 Aug, 1944 in the Bay of Biscay near La Rochelle, in position 45.52N, 02.36W, by depth charges from the Canadian destroyers HMCS Ottawa, HMCS Kootenay and HMCS Chaudiere. 56 dead (all hands lost).
Refitted as U-Flak 3 on 7 July 1943. Converted back to conventional U-boat.
U-621 operated with the following Wolfpacks during its career:
Panther (10 Oct 1942 - 16 Oct 1942)
Puma (16 Oct 1942 - 29 Oct 1942)
Raufbold (11 Dec 1942 - 18 Dec 1942)
Hartherz (3 Feb 1943 - 7 Feb 1943)
Ritter (11 Feb 1943 - 26 Feb 1943)
Burggraf (4 Mar 1943 - 5 Mar 1943)
Raubgraf (7 Mar 1943 - 15 Mar 1943)
Amsel 1 (3 May 1943 - 6 May 1943)
Elbe (7 May 1943 - 10 May 1943)
Elbe 2 (10 May 1943 - 14 May 1943)
Mosel (19 May 1943 - 24 May 1943)
Attacks on this boat
31 May 1943
18.42 hrs, mid Atlantic: While searching for survivors from U-563 sunk nearby, the inbound U-621 was herself attacked by a British Liberator (RAF Sqdn 224/Q, pilot Robert V. Sweeny). The aircraft dropped 12 depth charges on two runs, causing severe damage to the boat. (Sources: Norman Franks)
13 Jan 1944
While serving as a Flak boat U-621 was attacked by a British B-24 Liberator (RAF sqdn 59/A) off the Bay of Biscay, suffering 1 dead and 6 wounded. Matrosengefreiter Heinz Thomas was mortally wounded and later buried at sea. The commander decided to abort the patrol. U-621 took ten days to limp back to Brest.
11 Apr 1944
Returning from patrol in the Atlantic 621 ran into an Allied hunter-killer group 900 miles out from her base and fired a torpedo at a "destroyer", but missed. The boat then evaded the hunters and docked at Brest (Sources: Blair, vol 2, page 496)
9 Jun 1944
The boat returned to base at Brest with bomb damage caused by an unidentified aircraft. Date of attack may have been 1 day earlier. (Sources: Blair, vol 2, page 585)
4 recorded attacks on this boat.
Men lost from the boat
13 Jan 1944
While serving as a Flak boat on 13 Jan U-621 was attacked by a Liberator (RAF Sqdn 59/A) and suffered 1 man killed and 6 wounded. Matrosengefreiter Heinz Thomas was mortally wounded and later buried at sea. The commander decided to abort the patrol. U-621 took ten days to limp back to Brest.
Related: For more info on such losses see - Men lost from U-boats -