Initially envisioned as a tank that would support infantry engaged in the kind of trench-style fighting seen in World War I, the Infantry Tank Mark IV Churchill evolved into a lighter, well-armoured fighting vehicle, variants of which were deployed throughout World War II. (1) MAIN ARMAMENT A variety of main weapons were mounted on top of the Mark IV chassis, including the QF 2-pounder and 6-pounder guns, the American 75 mm (2.95 in), shown, and 76.2-mm (0.3-in) cannon, and a 95-mm (3.74-in) howitzer. (2) TURRET Both welded and cast construction were used in the production of Churchill Mark IV turrets. The 75-mm (2.95-in) cannon fitted later required a 90-degree rotation for loading from the left because of the crew configuration inside the turret. (3) ARMOUR PROTECTION Original specifications called for armour of 16 to 102 mm (0.6-4 in). However, later versions, beginning with the Mk VII, increased to 25 to 152 mm (0.98-5.98 in). (4) HULL DESIGN The Churchill's hull was divided into four separate compartments, with the driver forward, the engine and gear-box compartments to the rear, and the fighting compartment and turret at the centre. (5) SUSPENSION The coiled spring suspension was contained under panniers on each side with 11 bogeys carrying a pair of 25.4-cm (l Ovin) wheels. The configuration allowed the tank to traverse difficult terrain with relative ease. (6) ENGINES A pair of 261-kW (350-hp) horizontally opposed Bedford twin-six petrol engines remained in service with the Churchill even after heavier armament and armour protection caused greater weight and slowed the tank from its relative top speed of 24 km/h (15 mph).