Tank corps (Soviet Union)
A tank corps () was a type of Soviet armoured formation used during World War II. Pre-war development of Soviet mechanized forces. In Soviet Russia, the so-called armored forces (броневые силы) preceded the Tank Corps. They consisted of the motorized armored units (автобронеотряды) made of armored vehicles and armored trains. The country did not have its own tanks during the Civil War of 1918–1920. In January 1918, the Red Army established the Soviet of Armored Units (Совет броневых частей, or Центробронь), later renamed to Central Armored Directorate and then once again to Chief Armored Directorate  (Главное броневое управление). In December 1920, the Red Army received its first light tanks, assembled at the Krasnoye Sormovo Factory. In 1928, it began the production of the MS-1 tanks (Малый Сопровождения -1, where M stands for "small" and S – for "convoy"). In 1929, it established the Central Directorate for Mechanization and Motorization of the Workers’ and Peasants’ Red Army. Tanks became a part of the mechanised corps at this point. During this time, and based on the experience of the Civil War with its sweeping movements of horse-mobile formations, Soviet military theorists such as Vladimir Triandafillov and Konstantin  Kalinovsky elaborated the principles of combat use of armored units, which envisioned a large-scale use of tanks in different situations in cooperation with various army units. In the mid-1930s, these ideas found their reflection in the so-called Deep Operation and deep combat theories. From the second half of the 1920s, tank warfare development took place at Kazan, where the German Reichswehr was allowed to participate. In 1930, the First Mechanised Brigade had its own tank regiment of 110 tanks. In 1932, the first Mechanised Corps had over 500 tanks, and it was probably the first armoured unit of  operational significance anywhere in the world. That same year, the Red Army established the Military Academy of Mechanisation and Motorisation of the Workers’ and Peasants’ Red Army (which became the Malinovskiy Mechanised Force Academy and is today part of the Combined Arms Academy of the Armed Forces of the Russian Federation). In 1931–1935, the Red Army adopted light, medium, and later heavy tanks of different types. By the beginning of the 1936, it had already had four mechanised corps, six separate mechanised brigades, six separate tank regiments, fifteen mechanised regiments within cavalry divisions and considerable number of tank battalions and  companies. The creation of mechanised and tank units marked the dawn of a new branch of armed forces, which would be called armored forces. In 1937, the Central Directorate of Mechanisation and Motorisation was renamed to Directorate of Automated Armored Units (Автобронетанковое управление) and then to Chief Directorate of Automated Armored Units (Главное автобронетанковое управление, Габту, "GABTU"). Soviet armored units gained some combat experience during the Battle of Lake Khasan (1938), Battle of Khalkhin Gol (1939) and Winter War with Finland (1939–1940). In August 1938, the four mechanised corps were converted into tank corps. Each was authorized 12,710 men, between  560 and 600 tanks, and 118 artillery pieces. The corps included two light tank brigades (equipped with BT and T-26 tanks), a motor rifle and machine gun brigade, and a communications battalion. The 5th Mechanized Corps became the 15th Tank Corps, the 7th Mechanized Corps became the 10th Tank Corps, the 11th Mechanized Corps became the 20th Tank Corps, and the 45th Mechanized Corps became the 25th Tank Corps. In the summer of 1939, all three brigades of the 20th Tank Corps were detached from the corps and sent into combat during the Battles of Khalkhin Gol. The 15th and  25th Tank Corps fought in the Soviet invasion of Poland in September 1939. As a result of the Soviet assessment of the tank corps as being unwieldy and difficult to control, shown by repeated traffic jams caused by the tank corps in Poland, the Main Military Council ordered their disbandment on 21 November, replacing the tank corps with 15 motorized divisions, each with two motorized rifle regiments, an artillery regiment, and a tank regiment. The tank corps were not actually disbanded until January 1940, by which time the 10th Tank Corps had seen brief service in the Winter War in  December 1939. Besides the operational armoured and mechanised formations, separate tank battalions within rifle divisions existed. These were meant to reinforce rifle units for the purpose of breaching enemy defenses. They had to act in cooperation with the infantry without breaking away from it and were called tanks for immediate infantry support (танки непосредственной поддержки пехоты). With the fall of France, the People's Commissariat for Defense authorized formation of new mechanized corps. Unlike the corps formed in the 30's (which consisted of brigades), these corps (with over 1000 tanks each on paper) would consist of two tank and  one mechanized division plus support units (Red Army Handbook 1939–1945, Zaloga and Ness, pp. 65–68). These would be the armored formations which would attempt counter strikes against the German invasion. The performance of these corps was generally not good and they were officially disbanded in mid-July, 1941 (Ibid., p. 70). Additional information on these formations can also be found in Soviet Order of Battle World War II, Vol. I, by Charles C. Sharp. Eastern Front of World War II. On 31 March 1942, orders were given for the reformation of the tank corps, as a result of the Soviet  need for massed armored units so that the small tank brigades, which were now the basic armored formation, could be capable of decisive actions. The 1st, 2nd, 3rd, and 4th Tank Corps were to consist of a headquarters, two tank brigades, and a motor rifle brigade, authorized a total of 5,603 men with 20 KV heavy tanks, 40 T-34 medium tanks, and 40 T-60 or T-70 light tanks. The new tank corps lacked artillery, reconnaissance and engineer units, and rear support elements, although its component brigades included such formations. They were the equivalent of small Western armored divisions. The motor  rifle brigade was a new unit type intended to retain captured positions and to neutralize enemy infantry and anti-tank weapons. It was determined that this was too weak, and a third tank brigade was added to increase the offensive power. The final organisation as published in 1944 included an additional heavy tank or heavy self-propelled gun regiment, plus a medium and a light self-propelled gun regiment. A total of 31 tank corps were formed during the war, with 12 of them earning the designation of a Guards Tank Corps. Due to the destruction of the 21st Tank  Corps at the Second Battle of Kharkov and the use of some tank corps to form mechanised corps, no more than 24 of them actually saw combat. The tank corps were the basic building block of the Tank Armies (see List of Soviet armies#Tank Armies). Most tank corps were converted to Tank Divisions in 1945–6. See List of Soviet Army divisions 1989-91.