After the Second World War, Zhu encouraged his students in Kunming to oppose Chiang Kai-shek for starting the Chinese Civil War. In 1946, he returned to Beijing and was appointed the Head of the Chinese Language Department in Tsinghua University. When he heard of the assassination of patriotic authors Li Gongpu and Wen Yiduo, Zhu disregarded his own safety to attend the funeral of both men.
