Chatham Dockyard was kept very busy with emergency shipbuilding programmes during the Second World War. Of the eleven warships built between 1939 - 1945, nine were submarines: Umpire (1940); Una (1941); Splendid (1942); Sportsman (1942); Tradewind (1942); Shalimar (1943); Trenchant (1943); Turpin (1944) and Thermopylae (1945).
Wartime economies ensured that at the launch of HMS Turpin in 1944 - for the first and only time at Chatham - the submarine's launch cradle was hauled back up the slipway for re-use.
All but Thermopylae were completed in time to see active wartime service with the Royal Navy. Their operational successes included HMS Splendid's six wartime patrols in the Mediterranean between November 1942 - April 1943, during which she sank the Italian destroyer Aviere and over 30,000 tons (30,480 tonnes) of Axis shipping. On the 8th June 1945, HMS Trenchant, commanded by Commander A.R. Hezlet, R.N., sank the Japanese cruiser, Ashigara in the Banka Strait, Java. This was the largest warship to be sunk by a British submarine during the war.
