Mariner, the son of Mrs A. Wignall was 32 years old, and a private in the 2nd Battalion, The King's Royal Rifle Corps, British Army during the First World War when the following deed took place for which he was awarded the VC.

After climbing on the top of the German parapet he threw a bomb in under the roof of the gun emplacement and- heard some groaning and the enemy running away.

After about a quarter of an hour he heard some of them coming back again, and climbed up on the other side of the emplacement and threw another bomb among them left-handed.

"[1]William Mariner was killed on the evening of 30 June 1916 or the early morning of 1 July 1916 during a large scale raid in the Railway Triangle, south of Loos.

His death was witnessed by Giles E. M. Eyre and others who wrote "that Mariner seemed to lose control during a heavy bombardment, ran down an enemy trench and was last seen bayoneting a German as a shell exploded on him, blowing him to pieces.