HMS J2 (later HMAS J2) was a operated by the Royal Navy and the Royal Australian Navy.
Design and construction
The J class was designed by the Royal Navy in response to reported German submarines with surface speeds over . They had a displacement of 1,210 tons surfaced, and 1,820 tons submerged.
Operational history
J2 torpedoed and sank the German submarine between the Orkney Islands and Norway on 7 July 1917.
After the war, the British Admiralty decided that the best way to protect the Pacific region was with a force of submarines and cruisers.