The Ordnance QF 18 pounder was the standard British field gun of the First World War. It formed the backbone of the Royal Field Artilleryduring 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. This is the 1917 amended edition of the 1916 manual for the gun.