The 37mm Gun M3 was the first dedicated anti-tank gun fielded by United States forces. Introduced in 1940, it became the standard anti-tank gun of the U.S. infantry with its size enabling it to be pulled by a jeep. However, the continuing improvement of German tanks quickly rendered the 37 mm ineffective, and by 1943 it was being gradually replaced in the European and Mediterranean theaters by the more powerful British-developed 57mm Gun M1. In the Pacific, where the Japanese tank threat was less significant, the M3 remained in service until the end of the war.
Like many other light anti-tank guns, the M3 was widely used in the infantry support role and as an anti-personnel weapon, firing high-explosive and canister rounds.
The M5 and M6 tank mounted variants were used in several models of armored vehicles most notably in the Light Tank M3/M5, the Medium Tank M3 and the Light Armored Car M8. In addition, the M3 in its original version was mated to a number of other self-propelled carriages.