HMS Sidon was a Royal Navy S-class submarine launched in September 1944 by Cammell Laird & Co Limited in Birkenhead. As part of the third group of S-class vessels, she was built during World War II and named after the naval bombardment of Sidon in 1840. The submarine featured typical characteristics of her class, though specific dimensions are not provided in the source. Her service included participating in the 1953 Fleet Review celebrating Queen Elizabeth II’s coronation, marking her as an active part of post-war naval celebrations. However, her operational history was marred by a tragic accident in 1955. On June 16, while moored in Portland Harbour alongside the depot ship HMS Maidstone, Sidon was loaded with two Mark 12 high test peroxide-powered torpedoes, codenamed "Fancy," for testing. At approximately 08:25, an explosion occurred in one of these torpedoes, which did not detonate its warhead but caused catastrophic hull rupture. The explosion resulted from a malfunction in the torpedo’s high test peroxide engine, which ignited prematurely, spraying HTP onto copper fittings and causing an internal explosion. The blast tore open the torpedo tube, flooding the forward compartments. Twelve crew members died instantly, and seven others were seriously injured. The submarine began sinking by the bow, listing to starboard, and her commanding officer ordered evacuation. Thanks to rescue efforts from Maidstone, all survivors except the medical officer, Temporary Surgeon Lieutenant Charles Eric Rhodes, escaped; Rhodes tragically suffocated while aiding survivors and was posthumously awarded the Albert Medal. The wreck was raised later that year, and the casualties were buried with honors. The cause of the accident was attributed to the malfunction of the "Fancy" torpedo, which had begun a dangerous "hot-run," leading to the explosion. The faulty torpedoes were subsequently phased out by 1959. In 1957, the wreck was intentionally sunk off Chickerell, Dorset, to serve as an ASDIC target. The site remains a memorial and a point of interest, with efforts to raise the wreck continuing into the 21st century.

This description has been generated using GPT-4.1-NANO based on the Vessel's wikidata information and then modified by ShipIndex.org staff.