Iranian orders for an improved Chieftain led to what were initially relatively minor upgrades, but the development of Chobham armour in the 1960s led to the design of a new tank combining a wide variety of improvements, the Challenger. Among its many improvements, the Challenger used a laser rangefinder in a highly automated fire control system, an improved engine, a greatly improved suspension that offered far better off-road performance. Entering service in 1983, it was beaten into NATO service by the M-1 Abrams, which also used Chobham armour.
