The brutal plan of "maintaining public order and conducting mopping-up operations" was carried out by the Japanese invading forces from the beginning of 1939 to March 1940 to strengthen their occupation of north China. The plan included the launching of military attacks to destroy the anti-Japanese base areas, establishment of puppet organizations, building up of pro-Japanese armed groups, practice of "self-defense" and "self-government" to bring the masses under their control, and a policy of mollification to deceive the people.