Tank
Most modern tanks most often have four crew members, or three if an auto-loader is installed. These are the:
Historically, crews have varied from just two members to a dozen. For example, pre-World War II French tanks were noted for having a two-man crew, in which the overworked commander had to load and fire the gun in addition to commanding the tank. First World War tanks were developed with immature technologies; in addition to the crew needed to man the multiple guns and machine guns, up to four crewmen were needed to drive the tank: the driver, acting as the vehicle commander and manning the brakes, drove via orders to his gears-men; a co-driver operated the gearbox and throttle; and two gears-men, one on each track, steered by setting one side or the other to idle, allowing the track on the other side to slew the tank to one side.
Tank Corps, National Army
On 11 November 1918, the Tank Corps had 483 officers and 7700 enlisted men, and the consolidation of tank training had begun at Camp Benning when Dwight D. Eisenhower arrived from Camp Colt on 24 December 1918  (he remained until 15 March 1919,  and about 250 Camp Colt soldiers were transferred to Camp Benning after the armistice.) On 26 December 1918, a portion of the Camp Polk tank school was transferred to Camp Benning "to work in conjunction with the Infantry school". Camp Benning tank troops were moved to Camp Meade from 19–21 February 1919; and Clopton was ordered to Camp Meade on 24 February 1919).