Cyclops served during the
First World War as a repair ship with the
Grand Fleet where she served the entire conflict based at
Scapa Flow. She was paid off on 1 April 1919, then was recommissioned for White Sea duty at
Archangel. She returned to Chatham in October 1919 and on 31 January 1920 went into reserve for refit and conversion to a submarine depot ship, commissioning for the
1st Submarine Flotilla, Atlantic Fleet, on 21 December 1922 at
Chatham Dockyard. Between the wars HMS
Cyclops served in
Malta and was in reserve at the start of the Second World War before returning to Home Waters in late 1939 as the depot ship for the Royal Navy's
7th Submarine Flotilla based in
Rothesay. Between November 1939 and May 1940
Cyclops was the depot ship for the
3rd Submarine Flotilla, based at Parkeston Quay, Harwich Harbour. Her six S-class submarines reconnoitred and raided in the Heligoland Bight and off Denmark. She was nicknamed "Cycle Box". In December 1939 she used her 4-inch guns to engage a German seaplane attacking the harbour. On 6 May 1942, , and conducted practice attacks on a convoy made up of the submarine tenders
Cyclops, HMS
Titania and their escort
HMS Breda, and . She was commanded by Cdr.
Benjamin Bryant DSO, DSC, RN, from 30 October 1944 to 4 February 1945. ==Facilities==