The tank entered service too early before the design flaws had been ironed out and the Mk 1 and 2 were hardly battle worthy as the few used at Dieppe and in Tunisia in company with the more advanced Mk 3 proved. The Mk 3 was an altogether better design with a 6 Pdr gun replacing the original 2 Pdr in the redesigned turret, plus mechanical improvements, new tracks etc. The Mk 4 had a new cast turret again with the 6 pdr. The Mk 5 had a 95mm howitzer as a CS tank and the Mk 6 was a Mk 4 with the British 75mm QF gun (a re-bored 6 Pdr firing the same US ammunition as used in the Sherman&#8217;s M3 gun). The Mk 7 became the definitive Churchill with a new hull with greater armour protection and was slightly wider. It was slower than the earlier vehicles, but the combat mobility was just as good. It mounted the 75mm gun in a new fabricated turret with an all round vision cupola (common in German designs, but a rarity on Allied vehicles).