John D’Aeth was born in Benenden in Kent on 7 February 1899, the son of Reginald Hughes D’Aeth and Lady Selina Hughes D’Aeth.  He joined the Royal Navy in January 1912.  

He served in submarines from Acting Lieutenant to Lieutenant Commander from August 1920 in HMS L33 as the Navigator, then L19 and H31 as First Lieutenant, before completing his Commanding Officers’ Qualifying Course in January 1924.  

He commanded submarines HMS H52, H24, L56 and REGENT.  D’Aeth was promoted to Commander in June 1934 and in December 1934 was appointed to HMS DOLPHIN as Staff Officer (Operations).  He was appointed to the Cruiser HMS GLOUCESTER as the Commander in July 1938.  Commander James D’Aeth died whilst serving in HMS GLOUCESTER in the Mediterranean on 8 July 1940.  The ship was hit by bombs from Italian aircraft.  The bridge was hit and D’Aeth was killed, alongside the Captain and sixteen others of the crew.  

He was the husband of Mary Winifred Hughes D’Aeth and is commemorated on the Plymouth Naval War Memorial on Panel No. 36 Column No 1.