This differs from a cavalry troop or infantry platoon, in which the highest-ranking non-commissioned officer (NCO) is usually a sergeant.
It was introduced in 1813 to replace the quartermaster as the senior NCO of a troop, and was roughly equivalent to a colour sergeant in the infantry.
It was revived in 1938 as an appointment of the short-lived rank of warrant officer class III (WOIII).
The new troop sergeant major, and his infantry counterpart, the platoon sergeant major, were part of an experiment in giving experienced NCOs command of units (troops and platoons) formerly reserved for commissioned officers.
The experiment was not considered a success, and no promotions were made to the rank after 1940; most existing WOIIIs were commissioned as lieutenants.