The XE-class submarines were a series of twelve midget submarines that were built for the Royal Navy during 1944; four more to a slightly different design were built 1954-5 as the Stickleback class. They were an improved version of the X class used in the attack on the German battleship Tirpitz. They carried a crew of four, typically a lieutenant in command, with a sub-lieutenant as deputy, an engine room artificer in charge of the mechanical side and a seaman or leading-seaman. At least one of them was qualified as a diver. In addition to the two side charges (each of which contained two tons of amatol explosive), they carried around six 20-pound (9 kg) limpet mines which were attached to the target by the diver. They and their depot ship HMS Bonaventure arrived at Labuan (Malasia) in July 1945. XE8 "Expunger" - built by Broadbent, sunk as target 1952, recovered 1973 and preserved at Chatham Historic Dockyard, on loan from the Imperial War museum.