Adapted to meet the warmer conditions encountered in tropical climes, the XE class of midget submarines, developed by the Royal Navy during WWII, were slightly larger than the X-craft used in the attack on the German Battleship, ‘Tirpitz’, in 1943.
Carrying a crew of four – two of whom were designated as divers – the Royal Navy’s midget submarine, XE-4, under the command of Australian, Max Shean, was, in July 1945, tasked with disrupting Japanese communications by cutting the Vietnamese submarine telephone cables running north from Saigon to Hong Kong and south between Saigon and Singapore in an area of shallower water close to the Vietnam coast; an undertaking that would help hasten an end to the war in the Pacific.
Because of the water depths and the fact that the divers were breathing pure oxygen, dive times to depths below 33-feet were restricted. Using a grapnel, the small submarine discovered what was thought to be the Saigon-Singapore submarine cable at a depth of 50-feet. Max Shean reports that XE-4’s diver, fellow Australian S/Lt Ken Briggs, exited the submarine through the cramped W&D (wet and dry) compartment, and – because of oxygen toxicity issues – was not to remain at depth for more than 15-minutes.
“The understanding between us was that the diver should attach himself to the cutter hose.” – the pneumatic tool used to cut through nets and other obstacles that was kept in a compartment on the XE-craft’s upper casing – “Then, if he were overdue, we would surface, pull him aboard, dive immediately, revive him, and await any reaction from the Japanese.”
Five minutes later, Briggs re-entered the submarine to report that there was no cable, merely a patch of hard clay. Success came ten-minutes later with the discovery of the Saigon-Singapore cable lying at a depth of 44-feet and its subsequent cutting by Briggs.
Less than an hour later, the Saigon-Hong Kong cable was snagged at a depth of 45-feet. Exiting the submarine, S/Lt Adam Bergius, of the Royal Navy Volunteer Reserve, returned to report that although he had twice cut the cable, it had not parted. Armed with a second cutter, Bergius again exited the submarine, returning eleven minutes later with a length of the severed cable.
Armed with a full cargo of limpet mines, XE-4’s secondary target was to have been an attack on ships in the Mekong River. However, the two divers – having already had an exhausting day – the decision was taken to return to the mother submarine for the three-day tow back to their base in Brunei.
In his later report of the mission, Max Shean wrote: “The greatest risks were taken by the divers. Working at depths down to thirty feet was reasonably safe, despite the fact that three had been drowned when no deeper than this. Cutting the cables at the depths encountered did involve a real risk of loss of consciousness. Ken and Adam were aware of this and worked accordingly.”