In mid September 1943, Yasuji Okamura, commander of the Japanese Army in North China mustered four divisions and two brigades of the Japanese troops plus six puppet regiments of the public security corps and troops from the peace preservation corps involving more than thirty counties, totaling over 40,000 men, to carry out a mopping-up operation against the Beiyue area where the leading bodies of the Shanxi- Chahaer-Hebei Border Area were located by using the tactics of long-distance raid and diverging advance and converging attack. Xiao Ke, the acting commander of the Shanxi-Chahaer-Hebei Military Region, and Cheng Zihua, the acting political commissar, commanded the army of more than 40,000 soldiers and more than 180,000 militia men to unfold extensive guerilla warfare against the mopping-up operation conducted by the Japanese aggressors and their puppet troops.

　　On September 18, the Japanese and puppet troops of more than 17,000 men occupied the key points of Songshan of Yi County, Jiaotanzhuang, Huikou and Liulingguan of Pingshan County, Tangmei of Tang County, and Xiaguan of Lingqiu County. One third of the troops of the Shanxi-Chahaer-Hebei Military Region moved to the exterior line, and attacked the Japanese and the puppet enemy from the flank, while the rest two thirds stayed in the interior lines, and were dispersed by companies. And these companies integrated with the local militia to deplete and tire out the enemies by resorting to guerrilla warfare. On 25th, the Japanese and puppet troops invaded into the center of the base to carry out key point mopping up and suppression. More than 3,000 Japanese troops, covered by warplanes, tried to besiege the Shanxian Mountain area where the government of the Shanxi-Chahaer-Hebei Border Area and the leading bodies in the rear and the affiliated troops of the military region were located. The four companies of the No. 42 Regiment of the Third Military Sub-Region defended the Shenxian Mountain area by resorting to strategically located places of difficult access. After twelve days and nights of fighting, more than two hundred Japanese and puppet troops were killed or wounded, and the enemy's attack was frustrated.

　　Meanwhile, those troops who had moved to the exterior line cooperated vigorously with those fighting in the interior lines. They ambushed the Japanese troops in Houdang of Meng County. At one time, they broke into Wangdu, the town gate of Xingtang and the railway station of Ding County, and captured or seized over ten strongholds such as Shangchenyi and Xiban Village, forcing the Japanese to send back over 3,000 men to defend their strongholds. Under the constant attacks by the military and civilians in the Beiyue area, the Japanese and puppet troops had to pull back their troops to the major communication lines in early October from where they were dispersed to carry out the mopping up operation.

　　In the middle of October, the Japanese and puppet troops concentrated their main force totaling more than 9,000 men to loot grain and harass the autumn harvest in the grain-producing area along the rivers of Tanghe, Shahe and Hutuohe, and looked for an opportunity to wipe out the leading bodies and the affiliated troops of the Shanxi-Chahaer-Hebei Military Region. The military region concentrated the main force to continuously attack the Japanese and puppet troops that tried to loot grain in Sancha, Yingli, Danli and other places, and protected and helped the farmers to finish harvesting, plowing and sowing. In early November, over 2,000 Japanese and puppet troops assaulted the Shenxian Mountain area for the second time, but ended in having more than 200 men killed or wounded and one aircraft shot down.

　　In the middle of November, the Japanese and puppet troops began to withdraw by batches. The Shanxi-Chahaer-Hebei Military Region adopted the tactics of waging surprise attacks and ambush, and attacked the withdrawing Japanese and puppet troops with landmines. On December 10, the Japanese and puppet soldiers passed by Meng County and Pingshan area on their way of withdrawal. They touched more than 270 landmines in five days, and over 300 men were either killed or wounded. By 15th, all the Japanese and puppet troops were out of the revolutionary base.

　　During the anti-mopping-up operation in Beiyue area, the army and civilians killed, wounded and captured more than 11,000 Japanese and puppet soldiers, and captured more than 200 strongholds and blockhouses. At one time, they broke into thirteen cities and towns such as Baoding, Wangdu and Tang County, blasted eighteen trains, destroyed more than 240 tanks and vehicles, and shot down an aircraft, at the price of 2,400 dead or wounded.