American doctrine
Combined arms, crew survivability, and shooting first at night.
From exploitation to AirLand Battle
WWII U.S. tanks exploited infantry and artillery breakthroughs; tank destroyers were supposed to kill panzers. That split died in the 1950s. AirLand Battle in the 1980s assumed a Soviet echeloned attack in Germany: U.S. tanks would hit the first wave, while air and artillery wrecked the second. The Abrams was bought for that war.
The brigade, not the tank
An Armored Brigade Combat Team is combined arms by default: two combined-arms battalions (tanks + Bradleys), artillery, engineers, a cavalry squadron. The tank platoon (four hulls) never goes without infantry. Desert Storm and the 2003 run to Baghdad rewarded this. Urban 2004 (Fallujah) punished tanks that outran dismounts.
Design as doctrine
Blow-off panels, a human loader, DU armor, and a thirsty turbine are not engineering quirks. They are a written preference: the crew is expensive, fuel is a solvable logistics problem, and the first thermal sight wins. Compare a T-72’s carousel and you can read two philosophies without opening a field manual.