During China's War of Resistance Against Japan (1917-1941), the Japanese invaders in 1942 launched barbarous "mopping-up" campaigns against the Communist-led base areas in central Hopei Province. But the people there, every man, woman and child, inspired by Chairman Mao's thinking on people's war, joined in the war effort, closely co-ordinating with the Eighth Route Army units to develop guerrilla warfare over a large area, and creating the "tunnel warfare" that has become so well known. Making good use of tunnels, the army and people fought the Japanese aggressors and their local puppets, using various stratagems to wipe out the enemy's effectives. From an inferior force they grew into a strong one, going from the defensive over to the offensive at a time when the enemy was strong and we were weak. In the end the enemy "mopping-up" campaigns were smashed and the aggressors suffered decisive defeats.
