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The Medium Tank M2 was the first US medium tank to be produced in reasonable numbers, but was already obsolete by the time it entered production in 1939, and was soon replaced by the M3, itself seen as an interim design while work was completed on the M4 Sherman.
In 1936 work began on the Medium Tank T5. This marked a break with recent American medium tank designs, which had all used Christie suspension, with the ability to use tracks or wheels. The T5 used a number of components from the Light Tank M2, most notably its vertical volute spring suspension.
The T5 had three VVSS bogies on each side, each carrying two road wheels. The road wheels were attached to a central strut on almost horizontal pivoting arms. These were suspended from the top of the bogie on vertical volute springs (made by winding up a strip of sheet metal to produce a spring where the coils could slide over each other, thus increasing the range of movement). The T5 was armed with four machine guns mounted in sponsons at the corner of the fighting compartment, one 37mm high velocity gun and one machine gun in the turret, two machine guns in the bow front and could carry two anti-aircraft machine guns.
In June 1939 the T5 was standardized as the Medium Tank, M2. Eighteen M2s were authorised in Fiscal Year 1939, with production starting in the summer of 1939. Another 54 M2s were authorised for Fiscal Year 1940, but none of these would be built. Tests on the second M2 suggested that improvements were needed, leading to the M2A1, which was given a new larger turret, increased armour and a more powerful engine, but retained the 37mm main gun and multiple machine guns.
After the fall of France in the summer of 1940 the M2A1 was ordered into mass production. The Rock Island Arsenal was too small to produce the number of tanks required, and so in June 1940 Chrysler was asked if they could build the tanks. Chrysler agreed, and on 17 June 1940 received a full set of blueprints for the M2A1. On 15 August 1940 they were given a contract for the production of 1,000 M2A1s by August 1942. This would require the construction of a new Detroit Arsenal Tank Plant, which was to be complete by 15 September 1941. Production was to get underway within twelve months of the contract being issued, and reach 100 tanks per month within 15 months.
At the same time the US Army was studying the campaign in the Low Countries and France, and had come to the conclusion that the M2A1 was already obsolete. New Panzer IIIs were already armed with a 50mm gun, while the Panzer IV used a 75mm gun. Work had already been carried out on installing a 75mm gun in the chassis of the Medium Tank T5, and on 28 August 1940, only 13 days after it had been issued, the M2A1 contract was cancelled, and replaced with one for 1,000 of the yet to be designed Medium Tank M3s.
This didn't end production of the M2A1. The US Army was still desperately short of tanks, and the Rock Island Arsenal had the capacity to build a reasonable number. A contract was issued for the production of 126 M2A1s, and the first of this batch was completed in December 1940. By August 1941 a total of 94 had been completed, but by then production of the M3 had already reached 80 per month, making the M2A1 surplus to requirement and the remaining 32 tanks were cancelled.
The M2 and M2A1 were used as training vehicles in the Armored Force, before being declared obsolete late in 1942.
M2
The M2 was something of a compromise design. During the 1930s designs had been considered that carried most of their armament in a fully traversing turret and others that carried a heavy armament of machine guns carried in a fixed barbette superstructure. The M2 combined both of these features. The fighting compartment was a squashed octagon, with machine guns mounted on the four diagonal faces. These were carried in sponsons that resemble armoured barrels, with the gun in the front and an open back inside the fighting compartment.
A turret was mounted on top of this fighting compartment, and carried a high velocity 37mm M3 gun and another .30in machine gun. The turret had sloped sides and was also roughly octagonal in shape.
Two more machine guns were installed in the front of the hull, and there were fitting for two anti-aircraft machine guns, for a potential total of nine machine guns.
In order to operate all of these guns the M2 had a crew of six - commander, driver and four gunners!
The M2 was powered by a 350hp Wright air-cooled radial engine in the rear, with the final drive in the front. The driver sat above the drive, just in front of the turret, with sloping armoured plates running to the front and sides (resembling half a pyramid). Behind the superstructure was a flat engine deck. Steering was by a controlled differential system, which was far more effective at high speeds than the clutch and brake system used on earlier tanks.
One of the odder features of the M2 were the deflection plates fitted at the rear of the tank. The idea was that the M2 could drive over a trench, and the rear machine guns would be fired at the deflection plates, which would send bullets down into the space behind and below the tank. Perhaps unsurprisingly these plates weren't terribly effective.
M2A1
The M2A1 was largely similar to the M2, but with a more powerful 400hp engine, thicker armour, improved protection for the machine gun sponsons and a new turret. The new turret retained the roughly octagonal layout of the original (although with an increase in size), and had vertical rather than sloped sides, increasing the internal space. The M2A1 was standardized in 1940, but by then it was already obsolete, and plans for large scale production were massively scaled down.
Experimental Versions
The M2 was used for a number of experiments. The M2 with E-2 flame projector took a standard M2 and replaced the 37mm gun with an E-2 flame projector. Two flame fuel tanks were carried inside the tank.
The M2 was also used to test out extra armour kits, adding up to 3in to the existing armour at the cost of 9,500lb of extra weight.
Stats M2
Production: 15
Hull Length: 17ft 8in
Hull Width: 8ft 7in
Height: 9ft 4.5in
Crew: 6
Engine: Wright air-cooled 9-cylinder radial, 350hp
Max Speed: 26mph
Armament: One 37mm gun, eight machine guns
Stats M2A1
Production: 94
Crew: 6
Weight: 23 tons
Engine: Wright air-cooled 9-cylinder radial engine, 400hp
Max Speed: 30mph
Armament: One 37mm gun and eight machine guns
Armour: 1 1/4in