The 1920 Defense Act restricted tanks to the infantry. To allow the cavalry to have tanks of it's own, they were called "combat cars." In 1934-35 3 prototypes were developed. They were designated the T2, T2E1, and T2E2. The T2 was inspired by the British Vickers Armstrong 6 ton tank. The T2 was developed as an infantry tank and Rock Island Arsenal produced a similar tank for the calvary called the T5 Combat Car. It had vertical volute spring suspension instead of leave spring suspension. Modifications were made and soon it became the T5E2 which was eventually standardized as the M1 Combat Car.
It entered service with the US Army in 1937.
In July 1940 the new Armored Force was created and it abolished the distinction between infantry and cavalry tanks. These tanks were then renamed to Light Tanks.
The .50 cal MG fired at 2,850'/sec. The .30 cal MG at 2,800'/sec.
The Combat Car M1 was the basis for all following light tanks in the United States Army until 1944.
The hull was made from flat plates.
The Combat Cars used the vertical volute suspension. These were selected as it was much easier to maintain them than the Christie torsion bar suspension. Instead of a raised idler the M2 had a trailing idler wheel.
The first 58 had a D shaped turret that had 2 machine guns installed. Then they had octagonal turrets which sometimes had a machine gun installed for anti-aircraft protection.