Tank
With World War II the multi-turreted tanks proved impracticable, and as the single turret on a low hull design became standard, crews became standardized around a crew of four or five. In those tanks with a fifth crew member, usually three were located in the turret (as described above) while the fifth was most often seated in the hull next to the driver, and operated the hull machine gun in addition to acting as a co-driver or radio operator. Well-designed crew stations, giving proper considerations to comfort and ergonomics, are an important factor in the combat effectiveness of a tank, as it limits fatigue and speeds up individual actions.
Troop commander
A troop commander is an officer in the British Army, who commands 15 other soldiers (a "troop") and their vehicles. A troop usually consists of four or sometimes more armoured vehicles such as tanks and APCs. While serving in the Household Cavalry, Prince Harry was a reconnaissance troop commander, commanding six scimitar LRV-Cs.