The Ordnance QF 6-pounder 6 cwt Hotchkiss Mk I and Mk II was a shortened version of the original QF 6 pounder Hotchkiss naval gun, and was developed specifically for use in the sponsons of the later marks of British tanks in World War I, from Mark IV onwards.

The muzzles of the long barrels sometimes dug into the mud or struck obstacles when the vehicle crossed trenches or shell craters.

The shortened barrel incurred a reduction in muzzle velocity, but as tank guns in World War I were used against unarmoured or lightly armoured targets such as machine gun nests and artillery pieces at relatively short ranges of a few hundred yards, this was not a major disadvantage.

[1] The gun was reused in the Second World War, being fitted to the 12 Armoured Trains operated in the United Kingdom.

In 1940 as part of the British anti-invasion preparations, a large number of pillboxes were built to a design, known as Type 28 or FW3/28, intended for the modern 2-pounder anti-tank gun.