On this day, 84 years ago, on August 12, 1941 (June 20, the lunar calendar, 1941), the anti-"mopping up" began in the Shanxi-Chahar-Hebei Border Region. On August 12, 1941, under the leadership of the Communist Party of China, the anti-"mopping struggle" between the military and civilians in the Shanxi-Chahar-Hebei Border Region kicked off. After suffering a heavy blow in the Hundred Regiments War, the Japanese invading army was unwilling to lose. In 1941, they began to implement the "Public Security Strengthening Movement" and carried out crazy "mopping up" and "crusade" against the anti-Japanese base areas. From 1941 to 1942, when "sweeping" the North China base areas, more than 1,000 troops were used at a time, about 150 times; sometimes "sweeping" was repeated in the same area for three or four months, and the three-light policy of "burning everything, killing everything, and robbing everything" was also implemented. In the face of the enemy, the Shanxi-Chahar-Hebei Military Region carried out political mobilization and military preparations against "mopping up" in accordance with the orders of the Eighth Route Army Headquarters and changes in the enemy's situation, and mobilized militia and masses in the base areas to participate in the struggle. During more than two months of anti-"mopping up" operations, the military and civilians in Shanxi, Chahar and Hebei fought more than 800 times, eliminating more than 5500 Japanese and puppet troops. Many world-shaking and weeping heroes such as the "Five Heroes of Langya Mountain" emerged. On September 25, 1941, five soldiers from the 7th Company of the First Regiment of the Shanxi-Chahar-Hebei First Military Division led the enemy to the top of Langya Mountain in order to cover the relocation of troops and the masses, killing and wounding more than 90 enemy people. After running out of ammunition and food, the five soldiers would rather die than surrender and resolutely jumped off the cliff. On May 25, 1942, Zuo Quan, deputy chief of staff of the Eighth Route Army, died in battle. He was the highest-ranking military cadre of the Communist Party of China who died in the Anti-Japanese War. In the extremely arduous anti-"mopping up" struggle, the military and civilians behind enemy lines created many extremely effective methods to annihilate the enemy, such as sparrow warfare, tunnel warfare, mine warfare, and assault warfare, and developed the strategies and tactics of the people's war. The enemy was submerged in the vast sea of people's war. While the Shanxi-Chahar-Hebei base area won the anti-"mopping-up" campaign, it also made huge sacrifices. There were more than 2000 officers and soldiers and more than 4500 people killed or injured. The base area has shrunk by more than 4000 square kilometers. The North China Anti-Japanese Base Area has entered its most difficult stage. Comment: No matter how great the difficulties are, the Communist Party of China will not be defeated. There is a rectification movement in politics and self-reliance in economy.