The Ordnance QF 13-pounder[a] (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 intended as a rapid-firing and highly-mobile, yet reasonably powerful, field gun for Royal Horse Artillery (RHA) batteries supporting Cavalry brigades, and was expected to be engaged in mobile open warfare.

It was used by "L" Bty, Royal Horse Artillery in the defensive action at Néry, France, on 1 September 1914, for which three Victoria Crosses were awarded.

In 1940, some 13-pounders were brought out of store for use as emergency anti-tank guns, mounted in pill boxes,[11] for the home defence of Britain against possible German invasion.

[1] This was a pedestal-mounted adaptation by Vickers Limited of the Mark I horse artillery gun, intended to arm the Royal Navy's new Motor Launches in World War I.