The Legion joined one of the White Armies in the Russian Civil War. Janoušek fought in battles against the Red Army at Bugulma, Melekess, Braudina, Simbirsk and Kazan. On 7 August 1918 he took command of the 3rd Company of the 1st Regiment. In September the Red Army forced the Legion to retreat from Kazan. In October Czechoslovakia declared independence from Austria-Hungary, and in November the First World War ended with the armistices of Villa Giusti and Compiègne. But the Czechoslovak Legion was trapped in Russia, with the Red Army blocking its escape to the west.