Ernest Mitchell was born at Wells, Somerset, on 11 August 1877, the eldest of three children of John Mitchell, a railway porter, and his wife Mary Jane (née Hayes).

He joined the Royal Navy as a Stoker 2nd Class at Portsmouth on 29 April 1898, giving his previous occupation as porter. After a short period in the pre-dreadnought battleship HMS PRINCE GEORGE, and then various harbour service roles, he joined the new battleship HMS LONDON in June 1902, serving in the Mediterranean until April 1905.

On 1 October 1905 he joined the submarine depot ship HMS THAMES and over the next six years moved to depot ships HMS FORTH, HMS MERCURY and HMS ARROGANT, being rated Leading Stoker in August 1907, and Stoker Petty Officer in November 1909.  No details are held of the actual submarines he served in.  In April 1910 he re-engaged to complete 22 years service.

In December 1911 he returned to the surface Navy, and served in the training cruiser HMS MELPOMENE, before being drafted back to Portsmouth barracks in July 1913.  At the start of WW1, he was drafted to HMS DOLPHIN and then HMS MAIDSTONE, the principal depot ship of the Eighth Submarine Flotilla at Harwich. In April 1915 he was transferred to HMS ADAMANT for E15. Although this is the first mention of E15 in his record, it seems likely that he would have joined her around the date of her commissioning and joining the Eighth Flotilla in October 1914.  On 27 March 1915, the depot ship HMS ADAMANT left Harwich in company with HMS E11, E14 and E15 to join the Mediterranean Submarine Flotilla. E15 was the first submarine to attempt to penetrate the Dardanelles in order to be able to disrupt the Turkish supply lines to the Gallipoli peninsula.  The attempt failed when unexpected currents forced the boat aground, and she came under Turkish attack. The Commanding Officer and five of the crew were killed on 17 April 1915 and the remainder of the crew, including Stoker Petty Officer Mitchell, were taken prisoner. His service record notes that he died from malaria on 26 November 1916 at Belemedik, Turkey, whilst a prisoner of war. He was buried locally at the time, but after the Armistice was subsequently re-interred at Baghdad (North Gate) War Cemetery, Iraq.  He left a widow, Mary M (previously Wilson).