Tanks in World War I
The continued need for four men to drive the tank was solved with the Mark V which used Wilson's epicyclic gearing in 1918. Also in 1918 the French produced the Renault FT, the result of a co-operation between Estienne and Louis Renault. As mentioned before, it had the innovative turret position, and was operated by two men. At just 8 tons it was half the weight of the Medium A "Whippet" but the version with the cannon had more firepower. It was conceived for mass production, and the FT became the most produced tank of World War I by a wide margin, with over 3,000 delivered to the French Army. Large numbers were used by the Americans and several were also lent to the British.
United States Army enlisted rank insignia
In terms of command, the rank of a person typically determines what job and command the soldier has within a unit. For personnel in US Army mechanized infantry, a Bradley infantry fighting vehicle (M2A2) is commanded by a Staff Sergeant, the gun is manned by a Specialist or Sergeant and the driver is Specialist or below. For armor, the Abrams main battle tank (M1A2) is commanded by a captain, lieutenant, sergeant first class or staff sergeant; the gunner is a staff sergeant or sergeant; the driver is a specialist, private first class, PV2 or PV1; and the loader is a specialist or below.