The Americans met the start of WWII with about a dozen Convertible Medium Tanks T4 and a handful of Medium Tanks M2. Despite this poor state of readiness, American industry made some important steps even before the war that let them make up this gap very quickly. While battles were raging in Europe, the US launched first the Medium Tank M2A1 then the Medium Tank M3 into production. Solutions worked out on these vehicles allowed the development of a new generation medium tank: the Medium Tank T6. This vehicle was standardized as the Medium Tank M4 on September 5th, 1941.
Gun in a turret
The situation only changed during the development of the Medium Tank T5, the precursor to the Medium Tank M2. This tank was quite good for its time, but was not mass produced for a number of reasons. First of all, Americans also kept an eye on the situation in Europe and made proper conclusions. Second, the tank was built at Rock Island Arsenal, a factory intended to build artillery. It was simply not suited for building even the 17.3 ton Medium Tank M2, let alone the 18.7 ton M2A1.
|The first experience in building a fully cast turret platform and engine deck. Areas where bolts were to be installed can be seen. This is a feature inherited from the SOMUA S 35.
A decision to build a tank factory in Detroit was made in mid-June of 1940. However, the Medium Tank M2A1 did not remain a priority product for long. The Ordnance Committee developed requirements for a new medium tank with a 75 mm gun on June 13th, 1940. The tank was based on the M2A1 chassis, but this time the weapon was not fitted in a rotating turret. American industry was not ready for such a task, in part due to the cutting equipment required to make the turret ring. The largest turret ring they could provide was a 1380 mm wide. As a result, the Medium Tank M3 accepted into service on July 11th was in many ways a compromise. This tank was standardized before it was ever built in metal since the task was urgent and the army was in desperate need of medium tanks. The 75 mm M2 gun was located in a sponson on the right side of the hull. The tank's turret mounted a 37 mm M5 gun. Despite this strange design, the M3 was not a bad tank. It was quite an adequate vehicle for its time, especially if you compare it to what the British were building.
|The final design for a cast upper hull. The influence of the Ram tank can be seen. The same overall concept was used for the Medium Tank T6.
|A full scale model of the future Medium Tank T6. This model shows an exotic set of armaments: coaxial 75 and 37 mm guns.
|The final mockup. Work on the real thing began in May of 1941.
|This model used the M3 gun, but the prototype had the shorter M2. No other option was available.
|The Medium Tank T6 was built with a cast hull, but Rock Island Arsenal also prepared a welded design.
|The bottom part of the hull was unchanged compared to the Medium Tank M3.
|Chassis of the Medium Tank T6 in the process of assembly. The driver's seat allowed him to look out of his hatch while driving.
|The driver had two vision devices: a direct vision slit and a periscope.
|The assistant driver's station. The SCR 506 radio to his right partially covered the evacuation hatch.
|The experimental prototype only had a hatch for the driver.
|Turret of the Medium Tank M4A1. The T6 had a nearly identical one. The turret basket greatly hampered access to the driver's compartment.
|SCR 508 radio in the turret bustle.
|The cast upper hull.
|The Medium Tank T6 was shown at the Aberdeen Proving Grounds like this on September 3rd, 1941.
|The tank changed by mid-September. The commander's cupola disappeared and a counterweight was added to the gun.
|The rear of the experimental vehicle was identical to the model.
|Mobility trials continue, fall 1941.
|Medium Tank T6 in February of 1942. Instead of the M2 gun it now had the M3 with a longer barrel.
|Medium Tank T6 at the end of its life, 1947.