This is both the war memoir of a distinguished naval officer and the history of HMS Trenchant, a T Class submarine. Admiral Hezlet was appointed to command Trenchant from her completion in early 1944 until mid–1945 during which time she and her crew worked up, voyaged to the Far East and carried out five highly dangerous and successful operational patrols. On their arrival at Freemantle in July 1945, Trenchant had been at sea for 82 out of the last 94 days and covered 15,000 miles. More than that, she had sunk the Japanese cruiser Ashigara, the largest warship sunk by a British submarine, as well as a minesweeper, a submarine and a mass of miscellaneous enemy shipping. The crew's achievements were honoured by the award of seven DSCs, eleven DSMs and nine Mentioned-in-Despatches.