HMS L55 (Lt Cdr CMS Chapman) was deployed to the Baltic in 1919 during the Russian Intervention .

During operations against the Russian Fleet on 4 June 1919, L55 was sunk in action with destroyers Gavril and Azard (near Kronstadt in the Gulf of Finland). L55 fired two torpedoes at the destroyers which missed; then the submarine inadvertently surfaced and was hit by shellfire from the Russian warships. The pressure hull was not penetrated but the L55 then struck a mine on the edge of a British laid minefield and was lost with all hands. L55 was reported missing on 9 June 1919.

In 1928, the wreck of L55 was recovered; the bodies of the 42 crew members were returned to England aboard MV Truro, then transferred to HMS CHAMPION at Reval, Estonia, on 30 August 1928. An Estonian Guard of Honour fired three volleys and Royal Marine buglers sounded the Last Post. All shipping in the Port and government offices lowered their flags. HMS CHAMPION left the jetty with the band playing Chopin’s Funeral March. The coffins were buried in a mass grave in Haslar Royal Naval Cemetery. The funeral service was conducted by Bishop Southwell, Bishop of Lewes, the father of the First Lieutenant, Lieutenant Henry Southwell.

The submarine was refitted and incorporated into the Russian Fleet as a training submarine, and formed the basis of the Russian L Class mine-laying submarines. The submarine had a chequered career under Russian control, sinking for a second time, along with 50 men, in 1931. She was damaged in 1941 and was finally broken up in 1953.