XE - class submarine Six " XE " - class midget submarine s ( 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 . In addition to the two side charges ( each of which contained two tons of amatol explosive ) , they carried around six 20 - pound limpet mine s which were attached to the target by the 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 . Operations " Sabre " and " Foil " . These operations , carried out in July 1945 , were intended to cut the undersea telephone cables connecting Singapore , Saigon , Hong Kong and Tokyo . The intention was to oblige the Japanese to use radio and render themselves open to message interception . Operation " Sabre " was directed at the Hong Kong to Saigon telephone cable , and carried out by " XE4 " , which was towed to within of the Mekong Delta by the submarine HMS " Spearhead " , where she looked for the two telephone cables by using a towed grapnel . She eventually snagged the first cable , and managed to haul it about off the seabed . " XE4 ' s " diver , Sub - Lieutenant K . M . Briggs , used the net / cable cutter to sever it . The second cable was soon found as well , and was severed by the second diver , Sub - Lieutenant A . Bergius . Two divers were carried due to the operating rule that a diver should not spend more than 20 minutes in depths over and no more than 10 minutes over . " XE4 " and " Spearhead " returned to Labuan on 3 August 1945 . Operation " Foil " was directed at the Hong Kong to Singapore telephone cable and carried out by " XE5 " against the Hong Kong end of the cable , after being towed into position by the submarine HMS " Selene " . Operating close inshore near to Lamma Island , working conditions were poor , " XE5 ' s " divers having to work in thick mud under the constant threat of oxygen poisoning . Despite repeated attempts it was not completely certain that the cable had in fact been severed , and it was not until after the Japanese surrender that it was confirmed that " XE5 " had succeeded in doing so . " XE5 " and " Selene " returned to Subic Bay on 6 August 1945 . Operation " Struggle " . In August 1945 , HMS " XE1 " and " XE3 " executed a joint attack on Japanese warships within Singapore harbour . " XE3 " was tasked with mining the heavy cruiser " Takao " while " XE1 " was to attack the heavy cruiser " Myōkō " . The approach of " XE3 " along the Straits of Johor and through the various harbour defences took 11 hours plus a further 2 hours to locate the camouflaged target . Despite several opportunities for Japanese defenders to spot the vessel , " XE3 " successfully reached the " Takao " , fixed limpet mines and dropped its two , 2 - ton side charges . The withdrawal was successfully made and " XE3 " safely contacted HMS " Stygian " , the escort submarine . Meanwhile the crew of " XE1 " had failed to find their target . Instead , and knowing that the explosives already laid could explode , " XE1 ' s " own charges were also laid under the " Takao " . " XE1 " escaped successfully . The " Takao " was severely damaged and never sailed again . Lieutenant Ian Edward Fraser RNR , and Leading Seaman James Joseph Magennis were awarded the Victoria Cross ( VC ) for their part in the attack ; whilst Sub - Lieutenant William James Lanyon Smith , RNZNVR , who was at the controls of " XE3 " during the attack , received the Distinguished Service Order ( DSO ) ; Engine Room Artificer Third Class Charles Alfred Reed , who was at the wheel , received the Conspicuous Gallantry Medal ( CGM ) . " XE1 " ' s C / O , Lieutenant John Elliott Smart RNVR received the DSO , and Sub - Lieutenant Harold Edwin Harper , RNVR received the Distinguished Service Cross ( DSC ) ; and ERA Fourth Class Henry James Fishleigh and Leading Seaman Walter Henry Arthur Pomeroy received the Distinguished Service Medal . ERA Fourth Class Albert Nairn , Acting Leading Stoker Jack Gordan Robinson , and Able Seaman Ernest Raymond Dee were Mentioned in Despatches for their part in bringing the two midget submarines from harbour to the point where the crews that took part in the attack took over .