The designing works of heavy tank KV-1 started at the Leningrad Kirov factory on Feb. 1, 1939 under the leadership of J. Kotin. The first tests of the new tank were held on September 1, 1939. The tank had an anti-shell armour and was armed with two machine guns DT and 2 guns - 45-mm 20-K and 76 mm L-11. Because of the beginning of the Finnish War factory tests were interrupted and the tank was sent to the front, where proved to be very good. For the convenience of the crew the 45-mm gun was removed, and series tanks were armed with one gun, 76 mm.