The M4 Sherman, officially Medium Tank, M4, was the most widely used
The M4 Sherman evolved from the
When the M4 tank went into combat in
The relative ease of production allowed large numbers of the M4 to be manufactured, and significant investment in tank recovery and repair units allowed disabled vehicles to be repaired and returned to service quickly. These factors combined to give the Allies numerical superiority in most battles, and many infantry divisions were provided with M4s and tank destroyers. [N 3] 
After World War II, the Sherman, particularly the many improved and upgraded versions, continued to see combat service in many conflicts around the world, including the UN forces in the
The U.S. Army Ordnance Department designed the M4 medium tank as a replacement for the M3 medium tank. The M3 was an up-gunned development of the
The Sherman's reliability resulted from many features developed for U.S. light tanks during the 1930s, including
The T6 prototype was completed on 2 September 1941. The upper hull of the T6 was a single large casting. It featured a single overhead hatch for the driver, and a hatch in the side of the hull. In the later M4A1 production model, this large casting was maintained, although the side hatch was eliminated and a second overhead hatch was added for the assistant driver. The modified T6 was standardized as the M4, and production began in February 1942  The cast hull models would later be re-standardized as M4A1, with the first welded hull models receiving the designation M4.
As the United States approached entry into World War II, armored employment was doctrinally governed by
The armored division is organized primarily to perform missions that require great mobility and firepower. It is given decisive missions. It is capable of engaging in all forms of combat, but its primary role is in offensive operations against hostile rear areas. 
The M4 was, therefore, not originally intended primarily as an
United States doctrine held that the most critical anti-tank work (stopping massed enemy tank attacks) was primarily to be done by towed and self-propelled anti-tank guns, both of which were referred to as "tank destroyers", with friendly tanks being used in support if possible.  Speed was essential in order to bring the tank destroyers from the rear to destroy incoming tanks. This doctrine was rarely followed in combat, as it was found to be impractical. Commanders were reluctant to leave tank destroyers in reserve; if they were, it was also easier for an opposing armored force to achieve a breakthrough against an American tank battalion, which would not have all of its anti-tank weapons at the front during the beginning of any attack.