T5, the redesigned model (with a 350 hp R-975 radial engine) was redesignated as the M2 Medium Tank in June 1939. T1 Light Tank and T2 Medium Tank The T1 Light Tank and T2 Medium Tank were prototypes that were designed in the 1920s but soon became obsolete, although they would help development with later tanks. Marmon Herrington light tanks The Marmon-Herrington Combat Tank Light was a US light tank produced for the export market at the start of the Second World War. The CTL-3 had a crew of two and was armed with three M1919 Browning machine guns. A few saw combat in the Dutch East Indies campaign against the Japanese invasion. In mid-1942 a batch was diverted to Australia from the Dutch order where they were used for training After the attack on Pearl Harbor, some of these tanks were taken over by the United States Army and employed in Northern Alaska as the T14 and T16 respectively. There were also sent to Chinese Nationalist forces fighting the Japanese as more than 600 of the T16 CTMS tanks were delivered to China under Lend-Lease after Pearl Harbor. M2 Medium tank The M2 Medium Tank was a larger development of the M2 Light Tank and was first produced in 1939 by the Rock Island Arsenal, just prior to the war in Europe. Many components were common or used a similar design to the Light M2, 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-shoed 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 for a total of , and designated as the R-975 C1 radial engine. The M2 Medium Tank's unique features included a total of 7 M1919 Browning machine guns, whereas most tanks only had 1 or 2, bullet deflector plates, and sloped armor on the hull front (glacis plate). The main armament was a 37 mm gun, with 32 mm armor; the M2A1 had a 51 mm 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. Production for the M2 Medium Tanks