The Gun Carrier Mark I was a British vehicle of the First World War. The gun carrier was designed to transport a 6-inch howitzer or a 60-pounder gun forward soon after an attack to support infantry in advanced positions. Gun carriers were first used in the Battle of Pilckem Ridge (31 July – 2 August 1917) during the Third Battle of Ypres (31 July – 10 November 1917). The carriers moved guns and equipment but were used for the rest of the war mainly for carrying equipment and supplies through areas under fire, where porters in the open would have suffered many casualties. The 6-inch howitzer could be fired while mounted, making the Gun Carrier Mark I the first modern self-propelled gun, a weapon capable of independent action and having tactical mobility on the battlefield.