The Ordnance QF 18-pounder, or simply 18-pounder gun, was the standard British Empire field gun of the First World War-era. It formed the backbone of the Royal Field Artillery during the war, and was produced in large numbers. It was used by British Forces in all the main theatres, and by British troops in Russia in 1919. Its calibre (84 mm) and 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. The first versions were introduced in 1904. Later versions remained in service with British forces until early 1942. During the interwar period, the 18-pounder was developed into the early versions of the equally famous Ordnance QF 25-pounder, which would form the basis of the British artillery forces during and after the Second World War in much the same fashion as the 18-pounder had during the First. History During the Second Boer War, the British government realised that its field artillery was being overtaken by the more modern "quick-firing" guns of other major powers, and investigated replacements for its existing field gun, the BL 15-pounder 7 cwt. In 1900, General Sir Henry Brackenbury, the then director-general of ordnance, sent officers to visit European gun makers. At Rheinische Metallwaren und Maschinenfabrik in Düsseldorf, they found a quick firing gun designed by Heinrich Ehrhardt with a recoil system that totally absorbed all the recoil of firing, 108 guns plus spares, were secretly purchased and entered service as the Ordnance QF 15-pounder in June 1901. At the same time, the British Cabinet ordered Field Marshal Lord Roberts, the Commander-in-Chief in South Africa, to send home artillery brigade and battery commanders "selected for their eminence and experience" to form an Equipment Committee. The committee was chaired by General Sir George Marshall, who had been artillery commander in South Africa. It formed in January 1901 with a wide-ranging area of study from horse-drawn mobile guns and the larger more static field guns, to harness design, and even binoculars. They swiftly established the "conditions to be fulfilled by proposed new equipment"; the most important were the "weight behind the team", then ballistics, rapidity of fire, weight of shell, provision of shield and number of rounds carried. British gun manufacturers were invited to propose designs. Of the many entries, five for the horse artillery gun and