Operation Deadlight was the code name for the scuttling

Scuttling

Scuttling is the act of deliberately sinking a ship by allowing water to flow into the hull.This can be achieved in several ways—valves or hatches can be opened to the sea, or holes may be ripped into the hull with brute force or with explosives...

 of U-boat

U-boat

U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

s surrendered to the Allies

Allies

In everyday English usage, allies are people, groups, or nations that have joined together in an association for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out between them...

 after the defeat of Germany near the end of World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

.

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

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 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 with while 36 boats would be towed to ZZ for use as targets air 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 put into practice it was found that many of the U-boats were in an extremely poor position as a result of being moored in exposed harbours while waiting for 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

Prize (law)

Prize is a term used in admiralty law to refer to equipment, vehicles, vessels, and cargo captured during armed conflict. The most common use of prize in this sense is the capture of an enemy ship and its cargo as a prize of war. In the past, it was common that the capturing force would be allotted...

 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 rechristened 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 slated for scuttling but Rear Admiral Daniel V. Gallery

Daniel V. Gallery

Rear Admiral Daniel Vincent Gallery was an officer in the United States Navy who saw extensive action during World War II. He fought in the Second Battle of the Atlantic, his most notable achievement was the capture of the German submarine U-505, on June 4, 1944...

 argued successfully that she did not fall under Operation Deadlight. United States Navy

United States Navy

The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 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

Museum of Science and Industry (Chicago)

The Museum of Science and Industry is located in Chicago, Illinois, USA in Jackson Park, in the Hyde Park neighborhood adjacent to Lake Michigan. It is housed in the former Palace of Fine Arts from the 1893 World's Columbian Exposition...

 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.