When did chiang Kai shek start to fight japan?

Chiang Kai-shek began to fight Japan in earnest after the Marco Polo Bridge Incident on July 7, 1937, which marked the start of the Second Sino-Japanese War. Prior to this, he had been engaged in efforts to unify China and combat internal threats, but the invasion by Japan prompted a full-scale military response against the aggressors. Chiang led the Nationalist government in its resistance against Japanese forces throughout the conflict, which lasted until the end of World War II in 1945.