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.

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.

These operations, carried out in July 1945, were intended to cut the undersea telephone cables connecting Singapore, Saigon, Hong Kong and Tokyo.

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.

XE3s commander, Lieutenant Ian Edward Fraser RNR, and diver 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, 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).

[2] Author Douglas Reeman featured XE craft in two of his novels, the 1961 Dive in the Sun and Surface with Daring published in 1976.