Introduction to the first part: The main exhibition in the first exhibition hall is that after the Marco Polo Bridge Incident on July 7, 1937, Chiang Kai-shek was forced to abandon the idea that "we must first pacify the interior before resisting foreign aggression" and agreed to adapt the Red Army guerrillas from the eight southern provinces into The historical background of the newly formed Fourth Army of the National Revolutionary Army, the New Fourth Army.