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 . At the end of the war , Honecker resumed activity in the party under leader Walter Ulbricht , and , in 1946 , became one of the first members of the Socialist Unity Party of Germany ( Sozialistische Einheitspartei Deutschlands , SED ) , which was formed by the merger of the KPD and the Social Democratic Party ( SPD ) in the Soviet occupation zone of Germany .