Ernest Martin Jehan DSC (2 February 1878 – 7 December 1929) was a British officer in the Royal Navy during the First World War.

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.

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.

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 UB-4 and subsequently scuttled with explosives by a boarding party.

Jehan waited until the submarine came to 30 yards (27m) 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.

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 Inverlyon's fishing net.

As result of the battle, Ernest Martin Jehan was awarded the Distinguished Service Cross on 19 November 1915,[3] and promoted to lieutenant.

Daniel Herbert Jehan, who was possibly Ernest's twin brother, was also awarded the Distinguished Service Cross for his actions in the war.