M4 Sherman in the deserts of North Africa

The M4 Sherman, officially designated as Medium Tank, M4, emerged as the most extensively employed medium tank utilized by the United States and its Western Allies throughout World War II. Renowned for its reliability, cost-effectiveness in production, and widespread availability, the M4 Sherman served as the foundation for various other armored vehicles, including self-propelled artillery, tank destroyers, and armored recovery vehicles. Thousands were supplied through the Lend-Lease program to the British Commonwealth and the Soviet Union. The tank earned its moniker from the British, who named it after the American Civil War General William Tecumseh Sherman.

Originating from the M3 Medium Tank, which initially featured its main armament in a side sponson mount for rapid development, the M4 retained many of the earlier mechanical elements while relocating the primary 75 mm gun to a fully traversing central turret. While a one-axis gyrostabilizer aided in maintaining gun direction when stationary, it wasn't precise enough for firing on the move. Designers prioritized reliability, ease of production and maintenance, durability, standardization of parts and ammunition across a limited number of variants, and moderate size and weight for ease of transport and compatibility with existing bridging equipment restrictions.

These factors, coupled with the Sherman's superior armor and armament at the time, outmatched German light and medium tanks fielded between 1939 and 1942. The M4 holds the distinction of being the most-produced tank in American history, with 49,324 units produced, including variants. Throughout World War II, the Sherman led numerous offensives by the Allies after 1942.

When the M4 entered combat in North Africa with the British Army at the Second Battle of El Alamein in late 1942, it further tilted the balance of power in favor of the Allies in armored warfare, overshadowing the lighter designs of the Germans and Italians. Due to this success, the U.S. Army believed the M4 would suffice to secure victory, leading to limited pressure for further tank development initially. Logistical and transport constraints, such as limitations imposed by roads, ports, and bridges, also complicated the introduction of a more capable but heavier tank. Tank destroyer battalions, utilizing vehicles based on the M4 hull and chassis, with open-topped turrets and more potent high-velocity guns, also became prevalent in Allied armies.

Even by 1944, most M4 Shermans retained their dual-purpose 75 mm gun. By then, the M4 faced tanks with superior firepower and armor among the upgraded German medium and heavy tanks. However, it continued to fight effectively due to numerical superiority, greater mechanical reliability, robust logistical support, and backing from increasing numbers of fighter-bombers and artillery pieces. In the later stages of the war, a more formidable armor-piercing gun, the 76 mm gun M1, was integrated into production vehicles. For anti-tank purposes, the British retrofitted Shermans with a 76.2 mm Ordnance QF 17-pounder gun (known as the Sherman Firefly). Some were equipped with a 105 mm gun for infantry support roles.

The relative simplicity of production enabled the mass manufacturing of the M4, and substantial investments in tank recovery and repair units facilitated the swift restoration of disabled vehicles to operational status. These factors, combined, gave the Allies a numerical advantage in most engagements, with many infantry divisions being furnished with M4 Shermans and tank destroyers. By 1944, a typical U.S. infantry division was equipped with an attached M4 Sherman battalion, a tank destroyer battalion, or both.

Post-World War II, the Sherman, particularly its numerous improved and upgraded versions, continued to see action in various conflicts worldwide. It saw service with U.N. forces in the Korean War, with Israel in the Arab–Israeli conflicts, briefly with South Vietnam in the Vietnam War, and on both sides of the Indo-Pakistani War of 1965.