He joined the Young Communist League of Germany (KJVD), the youth section of the Communist Party of Germany (KPD), in 1926 and joined the KPD itself in 1929. Between 1928 and 1930 he worked as a roofer, but did not finish his apprenticeship. Thereafter he was sent to Moscow to study at the International Lenin School and for the rest of his life remained a full-time politician.