When the Red Army needed to mechanize its cavalry branch in the 1930s, the BT fast tank was its solution. Channeling the American Christie high-speed tank, the Red Army began a program to adapt the design to its own needs. Early versions were mechanically unreliable and poorly armed, but by the mid-1930s, the BT-5 emerged, armed with an excellent dual-purpose 45mm gun. It saw its combat debut in the Spanish Civil War in 1937 and was later used in the border battles with the Japanese Kwantung Army in the late 1930s. The final production series, the BT-7, was the most refined version of the family.

One of the most common types in Red Army service at the beginning of the Second World War, BT tanks saw extensive combat in Poland, Finland, the opening phases of Operation Barbarossa in 1941, and the 1945 campaign against the Japanese in Manchuria. This is the story of their design and development history.

Steven J. Zaloga received his B.A. in history from Union College and his M.A. from Columbia University. He has worked as an analyst in the aerospace industry for over two decades, covering missile systems and the international arms trade, and has served with the Institute for Defense Analyses, a federal think tank. He is the author of numerous books on military technology and military history, with an emphasis on the U.S. Army in World War II, as well as Russia and the former Soviet Union.

Henry Morshead is a design consultant in the European automotive and aerospace sectors, with clients including Jaguar, Bentley, Citroën and Airbus. He is also a technical sponsor of the Bloodhound supersonic car, contributing digital surfacing and design services. A former officer in the Royal Engineers and illustrator for Jane's, he maintains a keen interest in the design and use of military land and air vehicles.