Marshall's Horse was a South African cavalry unit formed in 1899 at the start of the Second Boer War to provide military support for the British campaign. The unit was created from the Uitenhage Rifles and 1st City (Grahamstown) Volunteers. They formed in Grahamstown, initially comprising 244 members before rising to 500 in late 1899. The unit's first commanding officer was Major George Marshall CMG.