He returned to Germany in 1931 and was arrested in 1935 after the Nazis had come to power ("Machtübernahme"). In 1937, he was sentenced to ten years for Communist activities and remained in captivity until the end of World War II. At the end of the war, Honecker started working for the communist party again under leader Walter Ulbricht. In 1946, he became one of the first members of the new Socialist Unity Party of Germany ("Sozialistische Einheitspartei Deutschlands", SED), made up of the old KPD and the Social Democrats of eastern Germany.