The Czechoslovak Legion (Czech: Československé legie; Slovak: Československé légie) were volunteer armed forces consisting predominantly of Czechs and Slovaks fighting on the side of the Entente powers during World War I and the White Army during the Russian Civil War until November 1919. Their goal was to win the support of the Allied Powers for the independence of the Lands of the Bohemian Crown from the Austrian Empire, and of Upper Hungary from the Kingdom of Hungary, which were then part of the Austro-Hungarian Empire. With the help of émigré intellectuals and politicians such as the Czech Tomáš Garrigue Masaryk and the Slovak Milan Rastislav Štefánik, they grew into a force of over 100,000 troops.
In Russia, they took part in several victorious battles of the war, including the Zborov and Bakhmach against the Central Powers, and were heavily involved in the Russian Civil War fighting Bolsheviks, at times controlling the entire Trans-Siberian railway and several major cities in Siberia.