Six XE-class midget submarines (HMS XE1 to XE6) were built for the Royal Navy during 1944. They were an improved version of the X Class midgets 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. They and their depot ship HMS Bonaventure arrived at Labuan in July 1945. Four of them managed to see action before the war ended.