The M4 Sherman, officially Medium Tank, M4, was the most numerous battle tank used by the United States and some other Western Allies in World War II. In spite of being surpassed by German medium and heavy tanks late in the war, the M4 Sherman proved to be very reliable, cheaper to produce and available in greater numbers. Thousands were distributed through the Lend-Lease program to the British Commonwealth and Soviet Union. The tank was named by the British for the American Civil War General William Tecumseh Sherman.

The M4 Sherman evolved from the interim M3 Medium Tank, which had its main armament in a side sponson mount. The M4 retained much of the previous mechanical design but put the main 75 mm gun in a fully traversing turret. One controversial feature, a one-axis gyrostabilizer, was not precise enough to allow firing when moving but did help keep the reticle on target, so that when the tank did stop to fire, the gun would be aimed in roughly the right direction. The designers stressed mechanical reliability, ease of production and maintenance, durability, standardization of parts and ammunition in a limited number of variants, and moderate size and weight. These factors, combined with M4 Sherman's then-superior armor and armament, outclassed German light and medium tanks of 1939–42. The M4 went on to be produced in large numbers. It spearheaded many offensives by the Western Allies after 1942.