A reference to the period from November 1937, around the time of the fall of Taiyuan, to October 1938, around the fall of Wuhan, when the Japanese aggressors launched a frontal attack against north China as Kuomintang troops retreated southwards. In order to persevere in the war of resistance in areas behind enemy lines in north China, the Chinese Communist Party and the Eighth Route Army under its leadership penetrated the enemy's rear area, waged guerrilla warfare independently there, recruited Party members in great numbers, established and consolidated Party organizations, vigorously expanded anti-Japanese armed forces, set up anti-Japanese governments and built anti-Japanese base areas.