[1] The flotilla brought together the newer, longer range 'overseas' submarines for the purpose of carrying out offensive operations.

On 5 August 1914, the Eighth Submarine Flotilla was based at its war station at Harwich and was constituted as follows:[3] Submarines Depot ships Attached Destroyers HMS D.1 was also notionally part of the flotilla, but was transferred to the Dover Patrol when war broke out.

It participated in the First Battle of Heligoland and the Cuxhaven Raid and covered the passage of the British Expeditionary Force to France.

Vessels based at Harwich were transferred to the re-established 9th Submarine Flotilla in August 1916 and only those submarines based at Yarmouth remained in 8th Flotilla[6] As at 1 October 1916 the flotilla was based at Yarmouth and formed part of the Harwich Force:[7] Submarines Depot ship As at 1 January 1919 the flotilla remained part of the Harwich Force, but following the suspension of hostilities had moved to Dover and was constituted as follows:[8] Submarines Depot ship Service summary:[9] Re-established on the East Indies Station at Colombo September 1939, disestablished again May 1940.

Principal events during 1944 in addition to the sinking of three merchant ships and 59 small coastal craft were as follows: Zwaardvisch torpedoed and sank U-168, 6 October 1944 Zwaardvisch torpedoed and sank the Japanese minelayer Itsukushima, 17 October 1944 Stoic returned home for refit and was replaced by HMS Spirit from 2nd Submarine Flotilla in December Operations continued from Fremantle in 1945, but up to the end of April enemy vessels proved hard to find.