The BT-5 improved on the previous BT-2, such as a new turret fitted with a 45 mm anti-tank gun that was also used on the T-26 and the BT-5's younger brother, the BT-7.

[1][2] The BT-5 would enter service in 1933, with the Red Army first seeing action with the Second Spanish Republic in the Spanish Civil War in 1937 until the end of World War II, with between 1884 and 2108 units being produced with production of the tank beginning in March 1933 with production ending in 1935.

When he failed to get the United States Army interested, he sold the design to the USSR.

Due to American sanctions on the USSR, Christie sold the design as tractors.

The BT-5 played a major role in the Battle of Khalkin Gol, as they were so fast that Japanese anti-tank gunners could not hit them.

The first real challenge for the BT-5 was the Winter War against Finland, where the BT-5 was unable to get past the Finnish defensive line, the Mannerheim Line, where their thin armor was easily penetrated by Finnish anti-tank guns.

Soviet losses, including tanks, were appalling at the beginning of the invasion.

The BT-5 would be used throughout the rest of the war, but not as much as its younger brother, the BT-7, or the new T-34, due to a lack of spare parts for the tank.

The BT-5 was used the most at the beginning of the invasion of the Soviet Union and near the end of the war when spare parts were available.