John Ackery was born in Lambeth, London on 5 November 1912, the son of Mr A P and Mrs Ackery. He joined the Royal Navy as a Midshipman (E) on 17 September 1931 and was appointed to the Engineering College at Keyham on the same date. He was promoted to Sub Lieutenant on 1 November 1933. Promotion to Lieutenant (E) followed on 1 November 1935 and, on 28 May 1936 he was appointed to aircraft carrier HMS HERMES.

He was appointed to HMS DOLPHIN for submarine training on 30 August 1937. On completion of the submarine course, he was appointed to HMS DOLPHIN to date 11 December 1937. He was then appointed to HMS NARWHAL as Engineer Officer on 29 November 1938. He was awarded the DSC – see London Gazette dated 23 February 1940.

HMS NARWHAL was lost with all hands after an attack by a Dornier aircraft, off Norway on 23 July 1940. John Ackery was the husband of Betty Ackery (née Gladstone).  He is commemorated on the Portsmouth Naval Memorial, Panel 37 Column 1.