Adventures in joint ventures - the Tank Mark VIII

Known as the Liberty or the International, the Tank Mark VIII was intended to be a pan-Entente joint venture, primarily designed by England, built in France using machinery and parts supplied by the United States. The plan was to build at least 1,500 tanks during 1918 in preparation for the 1919 offensive, with production starting in April and building up to a rate of 300 per month, with the factory being capable of expanding to 1,200 per month. This was a very ambitious plan, given that Britain's total tank production was around 150 per month.
The plan was not nearly adhered to. The factory was not complete until November (seven months after it was supposed to begin producing tanks), which was after the war had ended. The first engine (a modified Liberty aeroplane engine) wasn't complete until October, and the prototype hull didn't leave its factory in England until July. After the war, 100 were produced in the United States; total British production was 31, most of which were almost immediately scrapped.

Physically, the Mark VIII was an improved hybrid of the early Marks and the cancelled Mark VI. It had the rhomboid shape, but had an improved driver's position, rounded tracks to improve handling, and the first compartmentalization, isolating the engine from the crew and improving the quality of crew ergonomics.

The side sponsons contained the usual 6pdr L/23.5 cannon that had been standard since the Mark IV. However, there were no machineguns in the sponsons. Instead, one was mounted in the side of each hull behind the sponson. The box-shaped superstructure also had five machineguns; two forward and one on each other face. The British used the 7.7mm Hotchkiss machineguns. The Americans modified their tanks, removing the side superstructure guns (reducing the number of machineguns to five - two in the superstructure forward, one in the superstructure aft, and one on each side of the hull) and using Browning M1917s instead of the Hotchkiss.

Armor was barely improved, at only 16mm thickness on the hull and 6mm on the roof and floor. While a little better protected on the sides, it was still vulnerable to close-range armor-piercing fire.

The crew was either 12 (British) or 10 (American), consisting of the commander, driver, two gunners, two loaders, either five or three machinegunners (the loaders managed the hull machineguns), and a mechanic. They were also intended to carry a squad of 20 infantry.

This would be the last of the rhomboid heavy tanks. The trench-crossing requirements that led to their development wouldn't exist in the future, and future tanks would develop down a different path.

Survivors: Three of these tanks survive, one each at Fort Meade, Fort Benning, and Bovington. A mock-up made from an excavator and with a turret added was used in Indiana Jones and the Last Crusade.

Tank Mark VIII
Fire Control: 0
Armament: All: 57mm L/23.5 in left sponson, 57mm L/23.5 in right sponson
British: Hotchkiss Mk 1 left hull, Hotchkiss Mk 1 right hull, 2x Hotchkiss Mk 1 forward, Hotchkiss Mk 1 left, Hotchkiss Mk 1 right, Hotchkiss Mk 1 rear
American: Browning M1917 left hull, M1917 right hull, 2x M1917 forward, M1917 rear
Ammo: 208x57mm, 13,848x7.7mm (British) or .30-06 (American)
Fuel Type: G, A
Veh Wt: 37 tonnes
Crew: 12 or 10 (driver, commander, 2 gunners, 2 machinegunner/loaders, 5 or 3 machinegunners, mechanic)
Maint: 19
Tr Mov: 9/4
Com Mov: 4/2
Fuel Cap: 600
Fuel Cons: 50

Config: Veh
Susp: T: 6
HF 3
HS 3
HR 3