World War 2 In Review: M2 Medium Tank

Medium Tank M2, 1939.

The Medium Tank M2 was a United States Army tank that was first produced in 1939 by the Rock Island Arsenal, just prior to the commencement of the war in Europe. Production was 18 M2 tanks, and 94 slightly improved M2A1 tanks, for a total figure of 112. Events in Western Europe rapidly demonstrated that the M2 was obsolete, and it was never used overseas in combat; it was, however, used for training purposes throughout the war.

The M2's unique features included an unusually large number of machine guns, bullet deflector plates, and sloped armor on the hull front (glacis plate). The main armament was a 37 mm (1.5 in) gun, with 32 mm (1.3 in) armor; the M2A1 had a 51 mm (2.0 in) gun mantlet. The features of the M2 series development, both good and bad, provided many lessons for U.S. tank designers that were later applied with great success in the M3 Lee, M4 Sherman and many other armored fighting vehicles.

Rock Island Arsenal started work on a new medium tank, based on the design of the M2 Light Tank. Initially designated the T5, the redesigned model (with a 350 hp R-975 radial engine) was re-designated as the M2 Medium Tank in June, 1939. After the first 18 units had been produced at Rock Island Arsenal and evaluated by the army, the upgraded M2A1 specification was approved with a redesigned turret and a more powerful engine.

The medium tank M2 was a larger development of the M2 Light Tank. Many components were common or used a similar design, including the vertical volute spring suspension which would be used in later tanks as well. Twin-wheeled bogies were mounted externally, and rubber-bushed and rubber-shod track proved durable on roads. The initial M2 model was powered by an air-cooled Wright R-975 radial engine. For the M2A1, this engine was supercharged to provide an extra 50 hp (37 kW) for a total of 400 horsepower (300 kW), and designated as the R-975 C1 radial engine.

The M2 had a high superstructure, with a sponson-mounted machine gun in each corner. In addition, two more machine guns were fixed in the glacis plate and fired by the driver. Surmounting the superstructure was a small revolving turret armed with a 37 mm Gun M3 and a coaxial machine gun. The 37 mm gun could penetrate 46 mm of face-hardened armor sloped 30° at a range of 500 yards (457 meters), and 40 mm at 1,000 yards (914 meters). This armament configuration was a hybrid between the sponson-mounted weapons of the Mark VIII Liberty tank of World War I vintage, and the combination of turreted cannon, coaxial machine gun and glacis-mounted machine gun that was almost universal in World War II medium tanks. (Two additional .30-caliber machine guns could be mounted on pintles on either side of the turret for anti-aircraft use, bringing the total to nine—surely a record for any tank brought into service by any army.) The crew consisted of the tank commander, a driver and four gunners. The vehicle provided internal stowage for 200 rounds of 37 mm ammunition and up to 12,250 rounds of .30-caliber.

Bullet deflector plates were installed over the rear fenders. The idea behind these plates was that the tank could drive over a trench, and the rear sponson machine guns could then fire onto the plates; the bullets would deflect into the trench or the area directly behind the tank. Like the sponson machine guns themselves, the deflector plates turned out to be useless in modern warfare, since shooting at enemy troops in open trenches as a tank passed directly over proved to be a fairly unusual occurrence and a distinctly secondary manifestation of tank capabilities, with most engagements occurring at longer ranges.

Chrysler was appointed to manage a new tank plant, the Detroit Arsenal Tank Plant, to manufacture the M2, and the US Government contracted in August 1940 for 1,000 vehicles to be produced. Events in Europe made it obvious that the M2 was obsolete, and the government modified the contract two weeks later, before production began. Instead of M2 medium tanks, the plant would now build 1,000 M3 Grant tanks once they had been designed. In the interim production of the M2 was given to the Rock Island Arsenal, where 94 M2A1s were built up to August 1941. The M2A1 had slightly better armor and a slightly larger turret than the original M2, since it had the turret from the M3 Light Tank, with gun mantlet armor 2 inches (51 mm) thick.

The M2 was already obsolete when it entered service. It compared poorly with contemporary European tanks, such as the French S-35 and German Panzer III which could withstand 37 mm (1.5 in) anti-tank guns. The 37 millimeters (1.5 in) main armament of the M2 was equivalent to the 37 mm (1.5 in) the Panzer III, 47 mm (1.9 in) S-35 had more powerful guns. By 1941, Germany had upgunned the Panzer III with a 50 mm (2.0 in) L/42 gun, and the Soviets had fielded the vastly superior T-34, with a 76 mm (3.0 in) gun and a sloped 52 mm (2.0 in) glacis plate. Given this, the M2 was essentially a stopgap measure until more capable tanks like the M3 Lee and M4 Sherman came along in 1942-43. Although 18 M2s and 94 M2A1s were produced, the Ordnance office recommended in January 1942 that they should only be used for training purposes, and they were never sent overseas to combat areas. The U.S. Army fielded the M2 and M2A1 with the 67th Infantry Regiment (Medium Tanks) and, subsequently, the 1st Armored Division's 69th Armored Regiment during intensive training maneuvers in the United States in 1941, and the M2 design continued to prove useful in a basic training role for tank crewmen. The trained crewmen from the 69th Armored were scattered to provide cadres to several new armored divisions and independent M4 tank battalions, as U.S. armored forces were rapidly expanded in 1942-44.

For combat the M2 was generally a poor design, with thin armor, inadequate main armament and a high profile. The four sponson-mounted machine guns proved to be completely unnecessary and ineffective. But the design provided a few important lessons that were used for the later M3 and M4 medium tanks. In particular, the M2's sloped frontal hull (glacis plate) was extremely advanced for a 1939 design — the one bright spot in an otherwise dismal design — and a sloped glacis plate with substantially heavier armor would become a permanent feature of U.S. tank design. The next medium tank would have to match the German Panzer IV's 75 mm (3.0 in) turret gun. Since no suitable turret had been designed in the US, the Lee was designed first to mount a 75 mm (3.0 in) gun in the right sponson, which had been tested on an M2; the experimental vehicle was designated T5E2. The Lee's gun was mounted in a conventional turret on a modified M3, to produce the first Sherman eight months after the first Lee.

Specifications

Type: Medium tank

Place of origin: United States

Manufacturer: Rock Island Arsenal

Number built: 18 M2s; 94 M2A1s

Variants: M2; M2A1

Weight: 41,000 lb (18.7 metric tons)

Length: 5.38 m (17.7 ft)

Width: 2.59 m (8 ft 6 in)

Height: 2.82 m (9 ft 3 in)

Crew: 6 (commander, driver, 4 gunners)

Armor: M2 6.4–32 mm (0.25–1.26 in); M2A1 6.4–51 mm (0.25–2.01 in)

Main armament: 1× 37 mm Gun M3; 200 rounds

Secondary armament: 7× (maximum 9) .30-06 Browning M1919 machine guns; 12,250 rounds

Engine: Wright R975 EC2 air-cooled radial gasoline; 400/340 hp (298/253 kW)

Suspension: Vertical Volute Spring Suspension (VVSS)

Fuel capacity: 473 liters (125 U.S. gal)

Operational range: 210 km (130 mi)

Speed: 42 km/h (26 mph)

T5 Medium Tank Phase I.

T5 Medium Tank Phase III (M2 Pilot).

T5E1 Medium Tank.

Medium Tank T5E1.

Medium Tank T5 Phase 1.

M2 medium tanks.

M2A1 Medium Tank.

Medium Tank M2A1.

The M2 Medium Tank with E2 Flame Projector was an experimental mounting of the E2 Flamethrower unit upon the M2 Medium Tank.

An M2A1 Medium Tank (late production series).

The plethora of machine guns arming the Medium Tank M2 is well illustrated here. Each corner of the fighting compartment, each side of the bow, and the sponson roof anti-aircraft mounts all featured a .30 cal machine gun. Bullet deflector plates were installed over the rear fenders. The idea behind these curious additions was that the tank could roll over a trench, and the rear sponson machine guns could then fire onto the plates and the fire would deflect into the trench or the area directly behind the tank.

The turret on the M2A1 featured vertical sides to increase working room. The bullet splash deflectors on the hull front slope and rotor shields and sights on the sponson machine guns are also readily visible. The M2 family featured cooling fins on the final drive housings; these were dropped when the medium tank M3 was designed.

The T5E2 Medium Tank was the Phase III model reworked, mounting a 75mm Pack Howitzer in the modified right front of the vehicle, with the bow and rear corner machine guns being retained. A small six-sided cupola with rangefinder and machine gun replaced the turret. This was a test vehicle in the development of the Medium Tank M3.

T5E2 Medium Tank.

E2 Flame Thrower mounted in the M2 Medium Tank. Note the length of the flame thrower and its vulnerability when moving through wooded areas. Fort Knox, 11 June 1941.