In September 1939, Kott fought in the Polish army in its futile campaign against the German invasion and then, after a period in Lvov, returned to Nazi-occupied Warsaw. After World War II he became known initially as the editor-in-chief of the literary magazine "Kuźnica" and as Poland's leading theorist of Socialist realism. In 1949, as the communist authorities tightened their control over all aspects of life, Kott obtained a position as a professor in Wrocław and moved away from political life. He praised Joseph Stalin, but mostly concentrated on theater. In 1951, during the darkest period of Soviet terror, Kott published an ideological manifesto about the role of theater, entitled "O teatr godny naszej epoki" (For theater worthy of our times), in which he demanded a "new" theater subservient to the Party and its ideology. Historian Teresa Wilniewczyc noted, that his zeal for totalitarian control over the world of Polish culture was "far more than was required". Only after the Stalin era came to an end, did he become its ardent critic (March 1956). He renounced his membership of the communist party in 1957. In 1964 he was one of the signatories of the so-called Letter of 34 to Prime Minister Józef Cyrankiewicz regarding freedom of culture.