First generation
1945–1960. Centurion, T-54/55, M48, early M60. One tank replaces lights, mediums, heavies. Steel armor, optical rangefinders, 90–105 mm guns. The idea is new; the sensors are WWII’s children.
Second generation
1960–1975. Leopard 1, AMX-30, T-64, T-72. Stabilizers, the L7 105 mm as NATO standard, the 125 mm and autoloader in the East. A wrong turn: some designers thinned armor because ATGMs seemed to make it pointless (Leopard 1, AMX-30). Composite would prove them half-right.
Third generation
1975–2000. Abrams, Leopard 2, Challenger, T-80, Leclerc. Chobham/composite, 120/125 mm, thermal sights, 1,500 hp class engines. This is still the generation sitting in most sheds. Upgrades (SEP, A7, T-90M) are third-generation hulls with fourth-generation electronics.
Fourth, contested
APS as standard, unmanned or reduced crews, network as a weapon, 130–152 mm studies, drone integration. K2, Type 10, T-14, and the planned M1E3 / MGCS / Challenger 3 argue about what “fourth” means. Combat in Ukraine suggests the next tank is as much a node in an air-defense and EW bubble as it is a gun.