Wikipedia: The Ordnance QF 13-pounder (quick-firing) field gun was the standard equipment of the British and Canadian Royal Horse Artillery at the outbreak of World War I. It was developed as a response to combat experience gained in the Boer War and entered service in 1904, replacing the Ehrhard QF 15 pounder and BL 12 pounder 6 cwt. It was intended as a rapid-firing and highly-mobile yet reasonably powerful field gun for Royal Horse Artillery (RHA) batteries supporting Cavalry brigades, which were expected to be engaged in mobile open warfare. It was developed in parallel with the QF 18-pounder used by field artillery. The original Mk I barrel was wire wound. Later Mk II barrels had a tapered inner A tube  which was pressed into the outer tube. The first British artillery round on the Western Front in World War I was fired by No. 4 gun of E Battery Royal Horse Artillery on 22 August 1914, northeast of Harmignies in Belgium. It saw action most famously at the Battle of Le Cateau in August 1914 as the British Expeditionary Force retreated from Mons. It was used to great effect by "L" Bty, Royal Horse Artillery in its famous defensive action on September 1, 1914 at Néry, France, for which 3 Victoria Crosses were awarded. The medals, and No. 6 gun and limber involved in this action, are held in the collection of the Imperial War Museum.