Korsch's wartime experiences in Germany had radicalised him, especially the ferment within the leftwing parties of Germany following the Russian Revolution. Korsch focused his studies and writings on working-out a replacement economic system for workers' councils to implement across Germany, published under the title "What is Socialization?" in March 1919. Korsch was part of the USPD faction which joined the German Communist Party in 1920. This was despite his misgivings about the twenty-one Conditions required for adherence to the Comintern. He became Communist Minister of Justice in the regional Thuringian government in October 1923.