In 1920 he joined the Independent Social Democratic Party of Germany: he then joined the Communist Party of Germany in 1922. Between 1920 and 1924 he undertook a succession of jobs in various places, at one stage working as a miner at Hindenburg in Oberschlesien (as Zabrze had been renamed in 1915). In 1922/23 he was actively involved in opposition to French occupation of the Ruhr region. In 1923 the French authorities took him into "protective custody".