The M103 heavy tank, officially designated 120mm gun combat tank M103 was a heavy tank that served in the U.S. Army and the U. S. Marine Corps during the Cold War. Initially blueprinted by the U.S. Army as a heavy tank in late 1950, Chrysler was awarded the contract and produced the first prototype, T43, in November 1951. The M103 was designed to counter Soviet heavy tanks if conflict with the Warsaw Pact nations occurred. It was produced with a long-range 120mm cannon to destroy tanks at extreme distances.
Approximately 300 T43 heavy tanks were produced between 1953 and 1954. Unable to meet Continental Army Command standards, the heavy tank was put into storage in August 1955. Following the approval of nearly 98 upgrades the tank was redesignated the M103 Heavy Tank in April 1956. Of the 300 T43E1s built, 80 went to the US Army (some 74 of which were rebuilt to M103 standard), and roughly 220 were accepted by the US Marine Corps, to be used as infantry support, rebuilt successively to improved M103A1 and then later M103A2 standards.
The M103 heavy tank was considered obsolete when the US Army shifted to the concept of a single main battle tank optimizing firepower, protection, and mobility in a single medium tank design. In 1963 the U.S. Army inactivated all heavy armor units for newer main battle tanks. It was realized Soviet heavy tanks were not as effective as suspected, and the M103s were overkill and expensive against T-54 and T-55 tanks. The M103 heavy tank continued in service with the U.S. Marine Corps until 1973. The M103 heavy tank was never used in combat.
