 The Mercantile Marine War Medal was instituted by the Board of Trade and approved by the King to reward the war service of the officers and men of the Mercantile Marine who, while only trained as peacetime mariners, continued to serve while running the risk of being attacked at sea during the war.One or more voyages through a danger zone during the war qualified a mariner for the award of the medal, as did service at sea for not less than six months between 4 August 1914 and 11 November 1918.Men who served in coastal trades, such as pilots, fishermen and lightship and post office cable ship crews could also qualify.