John Shepard was born on 26 May 1875 at Edinburgh where his father, Thomas William Shepard, was serving in the Army with the Royal Scots.  His mother was Sarah Ann (née Fincham).  John was the second eldest of seven children and his siblings were born in India, Ireland, Glasgow and Aldershot.

He joined the Royal Navy on 15 September 1892 at the Boys’ Training Ship HMS ST VINCENT at Haslar, when his date of birth was recorded as 26 May 1876. He was rated Able Seaman in March 1895 and served in a variety of surface ships including the protected cruiser HMS INTREPID on the North America station and the Southampton Coastguard ships HMS AUSTRALIA and VENUS, also qualifying as a Torpedoman.  From October 1903 to November 1905 he served in the pre-dreadnought battleship HMS DUNCAN in the Mediterranean.

In December 1905 he joined the submarine depot ship HMS THAMES, and the following April transferred to the Portsmouth submarine depot ship HMS MERCURY, where he was rated Leading Seaman in September 1906. He remained with MERCURY until June 1909, when he transferred for a couple of months to HMS VULCAN, at that time the depot ship at Chatham, before returning to MERCURY where he was promoted Petty Officer in February 1910.  It is not known which, if any, submarines he served in during this period. In February 1911 he started four months at HMS VERNON followed by a year in HMS RACER, tender to the Royal Naval College at Osborne.  Then he had a year in the dreadnought HMS ST VINCENT, flagship of the newly formed 1st Battle Squadron. 

He returned to HMS DOLPHIN in June 1913, subsequently alternating with the new depot ship HMS MAIDSTONE which on the outbreak of war became the main depot ship for the Eighth Submarine Flotilla at Harwich. Although E15 is not mentioned in his record until April 1915, it seems likely that he would have joined her around her commissioning and joining the Eighth Flotilla in October 1914.  On 27 March 1915, the depot ship HMS ADAMANT left the Eighth Submarine Flotilla 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 Petty Officer Shepard, were taken prisoner. His service record notes that he died on 29 May 1916 at Sivas, Turkey, whilst a prisoner of war, from fever resulting from exposure to the sun.  

He left a widow, Amelia Jane (née Hinks), and two daughters. He is commemorated on the Basra Memorial, Iraq.