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.
Tank Corps of the American Expeditionary Forces
Brigadier General Samuel D. Rockenbach, as the Chief of Tank Corps for the American Expeditionary Forces under Pershing, organized, trained, equipped and then deployed the first American tank units to the Western Front of 1918 Europe. An initial plan for 2,000 light Renault FT tanks and 200 heavy British Mark VI tanks was changed to 20 battalions of 77 light tanks each and 10 battalions of 45 heavy tanks each. A total of eight heavy battalions (the 301st to 308th) and 21 light battalions (the 326th to 346th) were raised, but only four (the 301st, 331st, 344th and 345th) saw combat.