page_title: Tanks in the Soviet Union
section_title: World War II
hierarchical_section_title: Tanks in the Soviet Union / General developments influencing Soviet tank design / World War II
caption_attribution_description: T-50 WW2 tank
context_section_description: The participation by Soviet 'volunteer' tank units in the Spanish Civil War was decisive in forming Soviet tank designs for World War II. Soviet tanks dominated their foreign rivals in Spain due to their firepower, but their thin armour, in common with most tanks of the period, made them vulnerable to the new towed antitank guns being supplied to infantry units. This finding led directly to a new generation of Soviet tanks. In 1939 the most numerous Soviet tank models were the T-26 light tank, and the BT series of fast tanks.
  On the eve of World War II, the Red Army had around 8,500 T-26s of all variants.  The T-26 was a slow-moving infantry tank, originally designed to keep pace with soldiers on the ground. The BT tanks were cavalry tanks, fast-moving light tanks designed to fight other tanks but not infantry. Both were thinly armoured, proof against small arms but not anti-tank rifles and 37 mm anti-tank guns, and their gasoline-fuelled engines (commonly used in tank designs throughout the world in those days) were liable to burst into flames "at the slightest provocation." (Zaloga & Grandsen 1984:111) Development of various tank designs to find a replacement was begun, such as the T-50 light tank which was intended to replace the T-26 infantry tank. In prewar planning, the T-50 was intended to become the most numerous Soviet tank, operating alongside the BT fast tank. The sophisticated T-50 was developed keeping in mind the experience gained in the Winter War and Soviet tests of the German Panzer III tank. But because of technical problems, only a total of 69 T-50 tanks were built (only 48 of them armed), and the much simpler T-60 light tanks replaced it. In the meantime, a replacement for the BT fast tanks was being designed which would develop into the very capable and economical T-34 medium tank.
  In 1937, the Red Army assigned the engineer Mikhail Koshkin to lead a new team to design a replacement for the BT tanks at the Kharkiv Komintern Locomotive Plant (KhPZ) in Kharkiv. The prototype tank, designated A-20, was specified with 20 millimetres (0.8 in) of armour, a 45 mm (1.8 in) gun, and the new model V-2 engine, using less-flammable diesel fuel in a V12 configuration. The A-20 incorporated previous research (BT-IS and BT-SW-2 projects) into sloped armour: its all-round sloped armour plates were more likely to deflect anti-armour rounds than perpendicular armour. Koshkin convinced Soviet leader Joseph Stalin to let him develop a second prototype, a more heavily armed and armoured "universal tank" which could replace both the T-26 and the BT tanks.
  The second prototype Koshkin named A-32, after its 32 millimetres (1.3 in) of frontal armour. It also had a 76.2 mm (3 in) gun, and the same model V-2 diesel engine. Both were tested in field trials at Kubinka in 1939, and the heavier A-32 proved to be as mobile as the A-20. A still heavier version of the A-32 with 45 millimetres (1.8 in) of front armour and wider tracks was approved for production as the T-34. Resistance from the military command and concerns about high production cost were finally overridden by anxieties about the poor performance of Soviet tanks in Finland and the effectiveness of Germany's Blitzkrieg in France, and the first production tanks were completed in September 1940, completely replacing the production of the T-26, BT, and the multi-turreted T-28 medium tank at the KhPZ.
  The T-28 medium tank was deployed in the Invasion of Poland and later during the Winter War against Finland. In the course of these operations it was found that the armour was inadequate and programs were initiated to upgrade it. According to Russian historian M. Kolomietz's book T-28. Three-headed Stalin's Monster, over 200 T-28s were knocked out during the Winter War. Frontal plates were upgraded from 50 mm to 80 mm and side and rear plates to 40 mm thickness. With this up-armoured version, the Red Army broke through the main Finnish defensive fortification, the vaunted Mannerheim Line. The Soviets thus began to upgrade their T-28 tanks for the coming war with Germany, but 
caption: Up close with T50 light tank
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