onto the copper fittings inside the torpedo, decomposing into oxygen and steam. The torpedo's warhead did not detonate, but its hull burst violently, rupturing the torpedo tube and causing the flooding that destroyed the boat. The torpedo programme was terminated and the torpedoes taken out of use by 1959. Sidon was refloated, then sunk to act as an ASDIC target on 14 June 1957 at , off the coast of Chickerell in Dorset. On the 50th anniversary of the Sidon accident, 16 June 2005, the Dorset Branch of the Submariners Association erected a Memorial Stone to those who died. This is situated adjacent to the Portland Cenotaph at Portland, opposite the Portland Heights Hotel. A number of survivors and relatives of those who died in the accident attended the ceremony. Sidons wreck was purchased from the Ministry of Defence by the company Deepquest Sub Sea in 2000. In 2002 the company announced that it intended to raise the wreck. This had not occurred as of 2021. See also Submarines destroyed by hot-running torpedoes: Russian submarine K-141 Kursk Possibly References Publications External links HMS Sidon War Memorial HMS Sidon War Memorial at Portland, Dorset Explosions in 1955 British submarine accidents Submarine accidents caused by torpedoes British S-class submarines (1931) Ships built on the River Mersey Shipwrecks in the English Channel Maritime incidents in 1955 Wreck diving sites in the United Kingdom High-test peroxide Explosions in England 1944 ships World War II submarines of the United Kingdom Ships sunk as targets Maritime incidents in 1957 1957 disasters in the United Kingdom Disasters in Dorset