About this time, he became a member of a right-wing student group. Soon, in March 1919, he joined the Baden Freikorps and fought against the Bolsheviks as a part of the Baltische Landeswehr during the capture of Riga in May during the Latvian War of Independence. After the Landwehr was defeated in the Battle of Cēsis, he joined the German Legion of the West Russian Volunteer Army led by Pavel Bermondt-Avalov. In December 1919, after Avalov's forces were defeated by the Latvian Army and after a short time in Lithuania, Schlageter returned to Germany.