High Quality Content by WIKIPEDIA articles! The Ordnance QF 18 pounder, or simply 18-pounder Gun, was the standard British Army field gun of the World War I era. It formed the backbone of the Royal Field Artillery during the war, and was produced in large numbers. It was also used by British and Commonwealth Forces in all the main theatres, and by British troops in Russia in 1919. Its calibre (84 mm) and hence shell weight were greater than those of the equivalent field guns in French (75 mm) and German (77 mm) service. It was generally horse drawn until mechanisation in the 1930s.