The Ordnance BL 15-pounder, otherwise known as the 15-pounder 7 cwt, was the British Army's field gun in the Second Boer War and some remained in limited use in minor theatres of World War I. It fired a shell of 3-inch diameter with a maximum weight of 15 pounds, hence its name which differentiated it from its predecessor '12-pounder' 3-inch gun which fired shells weighing only 12.5 pounds. Wikipedia