The Churchill MK IV was first fielded in 1943 by the British Army.  They were widely used from Normandy to the end of the war; over a thousand were in service.  Over three hundred saw service with the Soviet Union.  Although the Australian Army ordered Churchills, not enough of them were shipped for them to see service before the end of the war.  The Churchill saw many variations, including bridge launchers, and engineer vehicles.  The MK IV was the most numerous mark of the Churchill tanks and was nearly identical to the older MK III.  Some MK IV had the main gun replaced with the 75mm gun from knocked out Sherman tanks.  The MK IV was such a stable gun platform that the 75mm Sherman gun actually had a longer range when mounted in the Churchill!  The MK V Churchill carried the short barreled 95mm howitzer in the main turret.  It had one of the lowest crew casualty rates of any Allied tank in World War Two.