Born in Forest, Guernsey, on 2 February 1878, Ernest Martin Jehan had worked as a plasterer before joining the Royal Navy on 8 February 1894, when he reached the age of eighteen; he signed up for 12 years service initially. At the age of 18, he was described as being with dark brown hair, brown eyes and a "dark" complexion. Jehan's first posting on 4 February 1894 was to the stone frigate HMS Impregnable, then based on the former HMS Howe, where he was ratedboy seaman. He was then moved to HMS Boscawen on 22 February 1895, then HMS Victory I on 10 July 1895 and HMS Australia on 12 September 1895, where on turning eighteen he was rated ordinary seaman. He briefly returned to Victory I from 6 February before being posted to HMS Fox on 14 April 1896. He was rated able seaman on 11 June 1896, when he also began specialist gunnery training. Jehan was posted to HMS Duke of Wellington I on 8 July 1899, and was rated leading seaman on 28 October 1899. He then transferred to the naval gunnery school HMS Excellent on Whale Island on 5 December 1899, and then briefly to the torpedo school HMS Vernon in September 1900, before returning to Excellent on 25 November. He was posted to HMS Duke of Wellington on 2 December HMS Raven on 9 December and back to Duke of Wellington I on 26 March 1901. He joined HMS Eclipse on 30 May 1901 and was rated petty officer 2nd class on 14 October. He returned Excellent 8 April 1903, and was rated petty officer 1st class on 17 June 1904. He briefly went back to Vernon on 28 June before returning to Excellent on 10 November. He was posted to HMS Sappho on 1 December 1904. Jehan was then promoted to acting gunner on 11 April 1905. He served as an interpreter during a visit to Portsmouth by the French fleet in August 1905 but failed a preliminary French exam in October that year. His rank was confirmed on 2 April 1906. He was largely employed on training duties in various establishments around Portsmouth until on 11 July 1910, he was appointed to the crew that took the light cruiser to Canada, one of two warships purchased by Canada from the British Admiralty. There he remained aboard the Canadian cruiser at Esquimalt, British Columbia, until ordered back to England in 1913, arriving back on 19 November. On 4 April 1914, just prior to the outbreak of the First World War, Jehan was posted to HMS Dryad, a torpedo boat converted into a minesweeper. From Dryad he was sent to Inverlyon as the commanding officer.
The Action of 15 August 1915 was a small naval battle involving Ernest Jehan. In 1915, the German Empire had begun its first U-boat campaign of the First World War. U-boats operated all around the British Isles, attacking allied warships and merchant vessels. The allies therefore began conducting counter-submarine activities. One of the first countermeasures to be taken was the deployment of Q-ships, merchant ships armed with hidden heavy weapons to lure out and destroy German submarines. Inverlyon, a fishing smack, was one of these vessels. Fitted with a 3-pounder and commanded by Jehan, Inverlyon sailed for enemy-infested waters. While sailing off the coast of Great Yarmouth on 14 August 1915, Gunner Jehan received news that a merchant ship, the Bona Fide, of 59 tons, had been stopped by the German submarine and subsequently scuttled with explosives by a boarding party. By the next day Ernest had rushed to the Bona Fide's last known position, at about 20:20 hours, The German sub surfaced near the Inverlyon. Then from the submarine's conning tower came the shouts from a German sailor ordering Inverlyons crew to prepare for boarding. Naturally the Q-ship disregarded the German officer's order. Jehan waited until the submarine came to 30 yards away, when he gave the command to raise the White Ensign and open fire. A series of three rounds from the sailing ship's gun struck the U-boat's conning tower and bridge, disabling the German commander. UB-4 then drifted behind Inverlyon, where her gun crew fired another six shots into UB-4s hull while others raked the sub with small arms fire. The U-boat then began to take on water from the bow area; the submarine was almost vertical before slipping beneath the waves and getting caught on Inverlyons fishing net. Because the submarine was caught on Inverlyons net, Jehan sent a message home asking if the submarine should be raised and salvaged. The Admiralty replied with a negative response, so the net was simply cut, allowing UB-4 to finish sinking to the bottom. All of the crew and commanding officer, Lt. Karl Gross, were killed. As result of the battle, Ernest Martin Jehan was awarded the Distinguished Service Cross on 19 November 1915, and promoted to lieutenant.
After ''Inverlyon''s cruise
By 1916, Jehan was relieved of the Inverlyon and sent to HMS Sarpedon as the executive officer. Later he commanded HMS PC-55 from 1919 to 1920 and retired on 29 October 1920. Jehan died on 7 December 1929 aged fifty-one.
