As the projected main user of the weapon, the Infantry Branch was chosen to oversee the work. In January 1937, the Ordnance Committee recommended development of such a weapon two PaK 36 guns were acquired for study. Combat experience from Spain suggested that a light anti-tank gun, such as the German 37 mm PaK 35/36, was capable of neutralizing the growing threat posed by tanks. Although some consideration had been given to replacing the machine guns with a more powerful anti-tank gun, the situation began to change only after the outbreak of the Spanish Civil War. In the mid-1930s, the United States Army had yet to field a dedicated anti-tank artillery piece anti-tank companies of infantry regiments were armed with. The inability of the 37mm round to penetrate the frontal armor of mid-war tanks severely restricted the anti-armor capabilities of units armed with them. In addition, the M3 in its original version was mated to a number of other self-propelled carriages. The M5 and M6 tank mounted variants were used in several models of armored vehicles most notably in the Stuart Light Tank M3/M5, the Lee Medium Tank M3, and Greyhound Light Armored Car M8. 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. In the Pacific, where the Japanese tank threat was less significant, the M3 remained in service until the end of the war, but some 57mm guns were issued.

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 57 mm gun M1. infantry with its size enabling it to be pulled by a jeep. Introduced in 1940, it became the standard anti-tank gun of the U.S. The 37 mm gun M3 is the first dedicated anti-tank gun fielded by United States forces in numbers.

Manhandling a gun into position during training at Fort Benning, 1942. M3 on display at Fort Sam Houston, Texas.

Us modern anti tank weapons