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.
Horses in World War II
The 1944 Cavalry Corps, in turn, had up to 103 tanks and tank destroyers in addition to three Cavalry Divisions that once again were made lean and light and dependent on horse alone (4,700 men with 76-mm field guns and no armor). By the end of the war with Germany, Soviet cavalry returned to its pre-war nominal strength of seven cavalry corps, or one cavalry corps per each tank army. The CMGs of the period (one Tank Corps and one Cavalry Corps) were regularly weapons of choice in operations where terrain prohibited the use of fully deployed Tank Armies.