Of the 156 U-boats that surrendered to the allies at the end of the war, 116 were scuttled as part of Operation Deadlight. The operation was carried out by the Royal Navy and it was planned to tow the submarines to three areas about 100 miles north-west of Ireland and sink them. The areas were codenamed XX, YY and ZZ. The intention was to use XX as the main area for scuttling while 36 boats would be towed to ZZ for use as targets for aerial attack. YY was to be a reserve position where if the weather was good enough, submarines could be diverted from XX to be sunk by naval forces. In the case of those submarines not being used as targets the plan was to sink them via explosive charges with naval gunfire as a fall-back option if that failed.
When Operation Deadlight was activated, it was found that many of the U-boats were in an extremely poor condition as a result of being moored in exposed harbours while awaiting disposal. Combined with poor weather, this meant that 56 of the boats sank before reaching the designated scuttling areas and those which did were generally sunk by gunfire rather than explosive charges. The first sinking took place on 17 November 1945 and the last on 11 February 1946.
U-boats excluded from Operation Deadlight
Several U-boats escaped Operation Deadlight. Some were claimed as prizes by Britain, France, Norway and the Soviet Union. Four were in the far east when Germany surrendered and were commandeered by Japan (U-181 was renamed I-501, U-195 - I-506, U-219 - I-505, U-862 - I-502, and a fifth boat, U-511, had been sold to Japan in 1943 and renamed RO-500). Two U-boats that survived Operation Deadlight are today museum ships. U-505 was earmarked for scuttling but Rear Admiral Daniel V. Gallery argued successfully that she did not fall under Operation Deadlight. United States Navy Task Group 22.3, under then-Captain Gallery, had captured U-505 in battle on 4 June 1944. Having been captured, not surrendered at the end of the war, she survived to become a war memorial at the Museum of Science and Industry in Chicago. U-995 was transferred to Norway by Britain in October 1948 and became the Norwegian Kaura. She was returned to Germany in 1965 to become a museum ship in 1971.
Deadlight U-boats discovered
In 2001 to 2003 nautical archaeologist Innes McCartney discovered and surveyed fourteen of the U-boat wrecks, including the rare Type XXI U-boat U2506, once under the command of Horst Von Schroeter and the successful Type IXC U-boat, U155 commanded by Adolf Piening.
- McCartney, Innes (February 2002). "Operation Deadlight U-boat Investigation". After the Battle.
- Waller, Derek (7 Nov 2010). "Operation Deadlight". uboat.net.
- Paterson, Lawrence (2009). Black Flag. The Surrender of Germany's U-Boat Forces 1945. Pen & Sword books. pp. 161–163. ISBN 978-1-84832-037-6.
- Paterson, Lawrence (2009). Black Flag. The Surrender of Germany's U-Boat Forces 1945. Pen & Sword books. p. 174. ISBN 978-1-84832-037-6.
- "uboat.net - Fates - U-boats after World War Two". uboat.net. Retrieved 12 February 2009.
- "Operation Deadlight Expedition phase 1 at uboat.net".
- "Operation Deadlight Expedition phase 2 at uboat.net".