When Britain required manufacturing muscle in World War 2 (1939-1945) it turned to American factories and relied on Lend-Lease for its supply as it faced the might of the Axis powers on battlefields across the world. In February of 1941, the United States Army set about adopting the British 6-pounder Anti-Tank (AT) gun using American production lines and this gave birth to the "57mm Gun M1". Manufacture of the gun began a year later and all of this early supply was shipped overseas.
The effectiveness of the design was not lost on American warplanners who found themselves requiring an effective tank-killing weapon all their own as the existing 37mm models were beginning to show their limitations against stouter enemy armor. Changes were introduced to the 57mm M1, mainly in the carriage component that utilized American wheels and tires, and this gave rise to the "M1A1" model. An improved "free-traverse" capability added in mid-1942 generated the "M1A2" designator and an all-new carriage design greeted the "M1A3" of 1943. This model featured a new towing hook and became the initial M1 version to be officially taken into service by the U.S. Army. The carriage component saw further changes to produce the "M2" of 1944 and "M2A1" of 1945 - the former had caster wheels on the right trail arm, relocated trail handles and an all-new utility box while the latter introduced an improved elevation gear arrangement.
The series eventually superseded the existing stock of 37mm M3 guns still in service with the U.S. Army and saw their first combat actions in North Africa. AP projectiles were the only ammunition available to M1 crews and this limited the flexibility of the armament against softer targets. It proved only marginally effective against most of the frontline German armor which had graduated from light-and-medium tanks to medium-and-heavy tanks as the war rolled into 1944-1945.
Nevertheless, the weapon saw service through to the end of the war with about 15,000 of the type produced in all. After the war, the 57mm M1 line was quickly retired as more effective measures for stopping enemy tanks became available.