Although larger and more powerful than previous British submarines, the J class could not keep up with surface vessels, and operated independently during the war.

They retained the 14.5-by-15-inch (368 by 381 mm) bore and stroke of these previous engines and produced 1,200 shaft horsepower at 380 revolutions per minute.

[3] The first boat, HMS J4 was commissioned at the height of the war on 17 July 1916 and assigned to the 11th Submarine Flotilla at Blyth in Northumberland, where it was soon joined by the others.

On 7 July 1917, HMS J2, sighted a U-boat and fired a four-torpedo salvo, of which one apparently hit, sinking SM U-99.

[4] The Australian government had a strong desire to include submarines in its new navy before the outbreak of the war and ordered AE1 and AE2 of the E class.

[5] At the end of the war, the Royal Navy looked to consolidate its large wartime construction program by retiring older ships or ships armed with 18-in torpedoes in favour of the units of the L-class patrol and H-class coastal submarines, which were armed with 21-inch (533 mm) torpedoes.

The J class, with their older pattern torpedoes and obsolete tactical concept were surplus to requirements and offered to the Australian government as a part of the gift fleet.

[6] The six submarines and the depot ship left Britain on 8 April 1919, and sailed via Gibraltar, Malta, Suez, Aden, Columbo, Singapore, Thursday Island and Moreton Bay.

Practice returns show that in the last quarter of 1920, the four operational boats made eighty submerged simulated attacks with 39 calculated to have hit.

This plan was authorised in August, and dredging, wharf construction, and reserve crews were performed at Flinders Naval Depot.

Four of the submarines, J1, J2, J4, and J5, were scuttled in Bass Strait, approximately 4 kilometres (2.2 nmi) west-southwest of the entrance to Port Phillip Bay, and are currently popular scuba diving sites.

The remaining two submarines were scuttled as breakwaters inside Port Phillip Bay, with J3 located near Swan Island in Queenscliff.