The British Ordnance BL 9.2 inch gun on truck, railway mounted a variety of surplus 9.2 inch naval guns, together with the custom-designed Mk XIII railway gun, on various railway platforms to provide mobile long-range heavy artillery on the Western Front in World War I. Mk XIII remained in service for British home defence in World War II.

The British mounted a 9.2 inch gun from the Cape Town coastal defences on a railway truck and sent it up the railway line to support the British assault on Boer defences at Belfast, north-east of Johannesburg.

The battle ended on 27 August 1900 before the gun arrived, and as the Boers thereafter resorted to guerrilla warfare this innovation was not used in action during the war.

They were mounted on Vavasseur slides, which travelled backwards and upwards to absorb the recoil, on "well-based" trucks, where the base was level with the axles.

The blast wave from the guns could damage civilian infrastructure so the rail spurs were generally in unpopulated areas.