The Combat Car M1 and M2/ Light Tank M1 was a light tank that was produced for the US Cavalry. Alongside the infantry's Light Tank M2 it was the basis of most American light tanks until 1944, although it was only produced in fairly small numbers and never saw combat.
The combat car designation was intended to bypass the National Defense Act of 1920, which had given responsibility for tanks to the infantry. General MacArthur, chief of staff of the US Army in 1931, decided that the cavalry also needed tanks if it was to be effective on a modern battlefield. As the cavalry wasn't allowed tanks, its new vehicles were designated as Combat Cars.
This pretence can't have been taken all that seriously but it did last for most of these vehicles' active service. In July 1940 the Armored Force was created, merging the infantry and cavalry tank units into a single force. After this the pretence could be dropped. The Combat Car M1 became the Light Tank M1A2 and the Combat Car M2 became the Light Tank M1A1.
The Combat Car M1 entered service with the US Cavalry in 1937. By 1940 when it became the Light Tank M1 it was obsolete, but it was still a useful training vehicle and was used at the training centre at Fort Knox.
The Combat Car M1 emerged from a series of experimental light tanks. The Light Tank T1 of 1926 was a two-man tank with a single 37mm machine gun and the engine at the front. The T1E1 of 1929 was a modified version which was briefly standardized as the Light Tank M1, but that designation was later revolted. The T1E2 was an improved T1E2 and the T1E3 had improved suspension.
Although it was still a member of the T1 series, the T1E4 saw dramatic changes. The engine was moved to the back of the vehicle, with the final drive at the front. The turret was moved to the centre of the tank and the suspension was based on the type used on the Vickers-Armstrong 6ton Tank Mk 'E'. The T1E4 was the basis of the Light Tank T2 of 1934, the start of the family that led to the Light Tank M2.
Work on prototype combat cars began in 1931-31 with the Combat Car T1, based on the Medium Tank T3, and the Combat Car T2, based on the Armoured Car T5. These designs were superseded by the Combat Car T5, which was developed at the same time as the Light Tank T2E1.
The Combat Car T5 had the same basic layout at the light tanks, with a Continental radial engine at the rear and the drive at the front. It used vertical volute suspension, which was retained on the production variants. It was armed with three machine guns, one in the hull and two mounted in two individual turrets mounted side-by-side in the middle of the vehicle. The T5 was built in 1934 at the Rock Island Arsenal. This vehicle was later given a Guiberson diesel engine and redesignated as the Combat Car T5E3.
Next was the T5E1 of 1934-35, in which the twin turrets were replaced with a barbette superstructure, with two machine guns mounted in its front.
The last development vehicle was the T5E2 of 1936. The barbette was replaced by a single turret which carried two machines mounted side by side. It was very similar to the Light Tank T2E1, and the two vehicles were designed to use interchangeable parts. They shared the same basic layout and were the same length, but had different turret designs. The Combat Car T5E1 was standardised as the Combat Car M1. At nearly ten US tons it was twice the weight of the original light tank specification of 1920.
The Combat Car M1 was the first production version of the tank. It had sliding gear transmission, and was armed with one .30 and one .50 machine guns in the turret and one .50 in the body. The M1 entered service in 1937. In 1940 it became the Light Tank M1A2.
The M1A1 had a constant mesh transmission. The turret was offset to the right and a radio was installed. Seventeen were built in 1938.
The Combat Car M2 had a Guiberson T1020 diesel engine, an improved turret and the idler wheel was moved down so that it touched the ground, increasing the vehicle's ground contact and improving the ride. Only seven were built. In 1940 the Combat Car M2 became the Light Tank M1A1.
The M1E1 was a single M1 that was given a Guiberson 250hp engine in
The M1E2 had a modified engine space and the rear bogie moved back by 11in.
The M1E3 was a M1 that was given a continuous band rubber track in 1939. It was later give a rubber block track. Both versions were only used for tests.
The M1A1E1 was an M1A1 with a Guiberson diesel engine. It was produced in 1938 and the same engine was used in the Combat Car M2.
The Combat Car T7 was a version of the Combat Car M1 but with a lengthened chassis and a new wheel and track suspension system that was similar to the type used on early Christie tanks. There were three main road wheels on each side, each of which could be fitted with pneumatic tyres if the tracks were removed.
Production: 90 (M1) 17 (M1A1), 7 (M2)
Hull Length: 13ft 7in
Hull Width: 7ft 10in
Height: 7ft 9in
Crew: 4 (commander, turret gunner, driver, hull gunner)
Weight: 19,644lb/ 9.8 US tons/ 8.8 imperial tons
Engine: Continental W-670 gasoline engine (250hp) in M1, Guiberson T1020 diesel in M2
Max Speed: 45mph (road), 15-20mph (cross-country)
Max Range: 100 miles road radius
Armament: One .5in and one .3in machine gun in turret, one .3in machine gun in hull