Editor-in-Chief: Cui Xiaohan Chief Writer: Xu Yan Question: Mao Xinyu's 1941 to 1942 was the most difficult period for the military and civilians behind enemy lines, and the base areas were drastically reduced in the Japanese army's frenzied "sweeping", "encroachment" and "law and order strengthening campaign", why did it enter a period of recovery in 1943? After the Japanese army entered 1943, with the victory of the Soviet Army in the Battle of Stalingrad, the Allied forces were about to open a second battlefield in Europe, and the Japanese army suffered successive defeats in the Pacific theater and lost the strategic initiative, shifting from strategic offensive to strategic defense. In order to get rid of the unfavorable situation in the Pacific Ocean, the Japanese authorities concentrated their forces on dealing with the attack from the US forces and were anxious to end the war against China. The invading Japanese army attempted to suppress and induce the Chiang Kai-shek regime by supporting the Wang puppet regime, so as to promote the convergence of the two major political forces of Chiang and Wang and rule China, so as to achieve the goal of striking at and dividing the anti-Japanese forces and stabilizing the Japanese battlefield situation in China. At this time, the Japanese army emphasized ensuring the security of important resource development areas, central cities, and major communication lines on the Chinese battlefield, and replaced part of the Japanese army as a garrison with a puppet army, so as to draw out troops for the Pacific theater and to carry out mobile combat missions in the Chinese theater. In order to fill the gap left by the transfer of troops, the Japanese army in North China expanded some brigades and regiments into divisions, but its total strength was still somewhat reduced, and its combat effectiveness began to decline. Although the puppet army has been increasing due to the large number of Kuomintang troops "saving the country from curves" and defecting to the enemy, their morale is not high and their combat effectiveness is low. 
Behind enemy lines in North China, under the leadership of the Northern Bureau of the CPC and the headquarters of the Eighth Route Army, the military and civilians in the base areas resolutely implemented a series of important principles and policies of the CPC on overcoming difficulties and overcoming difficulties; through the implementation of streamlining the administration of the army and launching a large-scale production campaign, they have already passed the most arduous period from 1941 to 1942, basically stopped the enemy's "encroachment" on the base areas, and thwarted the enemy's five "public order strengthening campaigns" in a row. In 1942 alone, the enemy carried out 77 "sweeps" with more than 1,000 troops in various anti-Japanese base areas in North China, of which 15 were large-scale "sweeps" with more than 10,000 troops. Although the base areas have suffered great losses, they have been tempered and have accumulated rich experience in struggle. From the winter of 1942, the anti-Japanese base areas in southern Hebei, central Hebei, and eastern Hebei began to recover, and by 1943, the entire anti-Japanese base areas in North China behind enemy lines had entered a new stage of recovery and redevelopment.
In view of the new situation in the battlefield behind enemy lines, the Eighth Route Army implemented the principle of "the enemy advancing and we advance," and the armed engineering teams that came and went without a trace behind enemy lines were a major creation of the military and people in the base areas in the struggle against "encroachment." Initially, the 129th Division organized armed propaganda teams and small units to carry out struggles in enemy-occupied areas to "burrow into the enemy's belly to fight." Because of the good results, it was quickly spread in various base areas, and was called light cavalry active in the enemy's heartland. In the course of encroaching on base areas and guerrilla areas, the Japanese army was equipped with "tight forces at the front and loose at the back, strong at the front and weak at the back." Due to the vertical and horizontal fortresses, the large forces of the Eighth Route Army could not enter the enemy-occupied areas, and the armed engineering team was capable of going freely behind enemy lines, and was able to effectively mobilize the masses, uproot strongholds, punish traitors, blow up bridges and roads, collect intelligence, and truly become the "sword in the arms and dagger in the sleeve" of the anti-Japanese army and people. 
In April 1943, the Japanese army carried out the last large-scale "sweep" of the Taihang base area, first forcing Pang Bingxun and Sun Dianying of the Kuomintang 24th Group Army in northern Henan to surrender, and then invading the Taihang base area in an attempt to encircle and annihilate the headquarters of the Eighth Route Army and the main force of the 129th Division on both sides of the Qingzhang River. The Eighth Route Army promptly ascertained the enemy's intentions, and the headquarters and the main forces jumped to the outer line in time before the enemy's encirclement was completed, and the troops left behind on the inner line, with the cooperation of the militia, used the method of combining mine warfare with cold guns to greatly deplete and delay the enemy. The troops of the outer line and the troops of the Taiyue and Southern Hebei subdivisions carried out offensive actions against the enemy, forcing the Japanese troops to retreat along the Pinghan, Zhengtai, and Tongpu railways.
In the same year, in order to eliminate the strategic threat of the puppet 24th Group Army to the Taihang District and the Hebei-Shandong-Henan Region, and to remove the obstacles to the next step of opening up the Tainan New Area, the main forces of the Eighth Route Army in Taihang and Southern Hebei launched the Lin (County) South Campaign, and at the same time, the Hebei-Shandong-Henan Military Region launched the Weinan Campaign to cooperate. In this battle, through the successful use of surprise attacks and strong attacks, interspersed with tactics such as division, encirclement and reinforcement, the Japanese puppet army was annihilated1There are more than 20,000 people, and the vast area with a population of more than 400,000 people in the south of Lin County and north of Hui County has been liberated. The victory in northern Henan was the largest battle fought by the Eighth Route Army after the Battle of the Hundred Regiments, which militarily dealt a blow to the encroachment attempts of the Japanese invaders, opened up vast areas in southern Weinan and northern Henan, and politically destroyed the enemy's policy of "governing China with China" and cultivating a puppet army. 
Mass guerrilla warfare blossomed everywhere, repelling the third upsurge of the Kuomintang In 1943, it was also a year of vigorous development of mass anti-Japanese guerrilla warfare, which not only showed universality and extensiveness in scale and scope, but also fully demonstrated diversity and flexibility in tactics. During the most difficult period of the War of Resistance Against Japanese Aggression behind enemy lines, the anti-Japanese base areas in North China combined the streamlining of the administration of the elite army with the localization of the main force, and encouraged and helped the militia and the self-defense forces to persist in the struggle on the spot. The shift in the focus of military construction in all military regions from expanding and consolidating the regular army to strengthening the building of local armies and militias will not only help overcome the financial difficulties in the base areas and reduce the number of non-productive personnel, but will also be of great significance in giving full play to the enthusiasm and creativity of the mass armed forces, enhancing their combat effectiveness, and promoting the extensive development of the anti-Japanese guerrilla warfare of the masses.
The deepest roots of the greatness of war are found in the people". The vast numbers of militia and self-defense forces that do not leave their jobs have given full play to their advantages of being familiar with the terrain of their own region and having flesh-and-blood ties with the masses of the people; they have carried hoes in one hand and knives and guns in the other, and they have not made mistakes in producing and fighting wars; through a protracted struggle against the enemy, they have not only created a form of guerrilla warfare that suits the characteristics of their own regions, but have also greatly improved their own tactics and skills. The militia in the central Hebei region created a "gate-blocking battle" in which the enemy was ambushed near the enemy's pillbox and attacked head-on as soon as the enemy went out, and a "capture war" in which the lone enemy was caught alive in the woods at the edge of the village according to the enemy's activity pattern. The militia in the Jinsui area demarcated a joint defense cordon, set up a sentry post on the cordon, and deployed reconnaissance personnel in front of the outpost to extend the sentry post to the vicinity of the enemy's stronghold, and promptly alerted the police in case of any situation. While carrying out the "sparrow war", the militia in Shandong also carried out the "wheel war" in which the enemy went to the militia to fight, the "push and grind war" in circles with the enemy, and the "honeycomb war" in which a village rushed to help. 
In the spring and summer of 1943, the Chiang Kai-shek clique of the Kuomintang set off the third upsurge. Since March, Wang Zhonglian has been in northern Jiangsu. Han Deqin launched attacks on the Communist-led base areas in Huaibei and Li Xianzhou in Shandong, but they were both repulsed. After a series of military provocations were frustrated, Chiang Kai-shek mobilized hundreds of thousands of troops to intensify the encirclement of the border areas, preparing to occupy the Guanzhong sub-district and then Yan'an. The CCP decided to continue to adhere to the principles and principles of "no one offends me, I will not offend anyone, and if anyone offends me, I will offend others" and "reasonable, beneficial, and modest", on the one hand, politically fully expose Chiang Kai-shek's crimes of launching a civil war and sabotaging the War of Resistance, and on the other hand, militarily make preparations for counterattacks and offensives. ** In addition to transferring the 358th Brigade from the Jinsui Border Region to strengthen the defense forces of the Shaanxi-Gansu-Ningbo Border Region, the Central Military Commission also transferred troops from various military regions in North China to defend the border region. In the face of the Chinese Communist Party's military preparedness and strong pressure at home and abroad, Chiang Kai-shek was forced to stop the military operation to attack the Shaanxi-Gansu-Ningbo border region, and the third ** climax was completely bankrupt.
The upsurge of smashing the Japanese army's "sweeping" and "encroachment" and repelling the Kuomintang authorities, coupled with the smooth development of the large-scale production movement, solved the difficult situation faced by the anti-Japanese base areas. By the end of 1943, the population of the Communist-led base areas had recovered from 50 million the previous year to 80 million. Although the main force has been reduced somewhat after the implementation of localization, the local armed forces have developed considerably, and they are more suitable for waging guerrilla warfare behind enemy lines.