The silent smoke of gunpowder in the south is filling, for their own interests, many people do not care about the survival of the country, the national righteousness, they will only care about one issue, that is, their own interests, even when the interests are redivided, they do not get much, and they are not willing to lose a little, if anyone violates their vested interests, that is the enemy, this is most of human nature, especially the people in the deep political whirlpool, they like to sing a gentleman's high profile, in front of a despicable villain.

However, the north is also constantly staging great changes and great turbulent turns.

After Li Zicheng entered Beijing, in order to disintegrate the remnants of the Ming army, he repeatedly sent envoys to recruit Wu Sangui, the chief soldier of Shanhaiguan, and the news of Chongzhen's hanging heralded the fall of the Ming Dynasty, so that Wu Sangui lost his reliance, in order to find a new master, after more than a month, Wu Sangui carried out speculative activities among various political forces. Later, when he heard that his concubine Chen Yuanyuan was taken captive by Li Zicheng's subordinates, he gave up and counterattacked Shanhaiguan, officially breaking with the Dashun regime.

After Wu Sangui learned the news that Li Zicheng personally led the army to the east, he immediately sent six people, including the gentry of Shanhaiguan, Confucian scholars Li Yousong, Tan Dihuan, Liu Tailin, Liu Taishan, Huang Zhen'an, and Gao Xuan, to "light up the thieves" to greet Li Zicheng's army in Sanhe County, expressing his intention to surrender, so as to delay time and wait for the movement of the Qing army outside the Guan.

"Wu Sangui just came to borrow troops to suppress thieves, and he didn't mean to surrender to our court, right?" When Dolgon, who was stationed in Jinzhou and was ready to reap the benefits of the fisherman, saw Wu Sangui's letter asking for help and borrowing troops, he felt very funny, did he have such a good friendship with him, why did he lend him troops, it was simply a big joke, what Wu Sangui said The conditions for the division of the north and south of the Yellow River are also nonsense in his opinion, and now the north of the Yellow River is in Li Zicheng's hands, and it is not his Li Zicheng's territory, he will beat the abacus too loudly, as if he is a fool.

Dolgon threw the letter aside, turned to Hong Chengchou and asked, "Hong Chengchou, you know the situation in the pass best, Wu Sangui sent someone to borrow troops, how do you think we should deal with it?" ”

Hong Chengchou also hurriedly bowed down and said: "According to the judgment of Wu Sangui's letter, it must be that Wu Sangui has broken with Li Zicheng, and it is Li Zicheng who has already marched to Shanhaiguan, and now Wu Sangui knows that his troops are insufficient. The conditions he said were actually not worth believing at all, but this was a good opportunity for our Korean soldiers to enter the Central Plains, and Wu Sangui wanted to be tactful and profitable, so we forced him to take a position. ”

Dolgon is naturally strategic, and already has a way to deal with Wu Sangui, hearing Hong Chengchou say this, he also smiled slightly, and said with a sneer: "Hmph! He Wu Sangui has Wu Sangui's calculations, and I have my plans. I, Dolgon, am the regent of the Qing Dynasty in the Qing Dynasty, and I am not his friend of Wu Sangui, nor is it his friend of the Ming Dynasty, how can I listen to his dispatch of Wu Sangui! He said that if he borrowed soldiers, he would borrow soldiers, which is ridiculous! ”

Fan Wencheng next to him also asked Hong Chengchou: "Lord Hong, according to your understanding of Wu Sangui's person, do you say that Wu Sangui will surrender to my Qing Dynasty?" ”

Hong Chengchou thought for a while, and replied with a frown: "It's hard to say, Wu Sangui is repetitive, good at speculation, if the situation is unfavorable, it is possible to surrender, but we also need to seize the opportunity and use it properly, Wu Sangui can hope to submit to my Qing Dynasty." He surrendered to Li Zicheng, and then rebelled, and now he must be wary! Hong Chengchou didn't dare to pack the ticket, after all, Wu Sangui's personality is not particularly clear to him, his understanding is limited, according to his impression, when there is half a chance, after all, there is a precedent for him to surrender to Li Zicheng, whether he will be now, it is really hard to say.

Dolgon is very confident, he and Wu Sangui are also old rivals, and they also know Wu Sangui quite well, and said disdainfully at the moment: "This time, that time." At that time, although the Ming Dynasty died, Wu Sangui had a supply of food and salary, so Wu Sangui still had the capital to waver, but now he is trapped on both sides, he is unwilling to submit to our dynasty, then he Wu Sangui can only be trapped in the lonely city, there is no reinforcements, and there is no food and salary to help, and the army is not as strong as Li Zicheng, sooner or later it will be a dead end, so he will ask for help from our dynasty. For decades, our dynasty always wanted to enter the Central Plains and rebuild the prosperous situation of the Great Jin Dynasty, all because Shanhaiguan was not in my hands, cutting off the way for my army to enter and exit, so this is a once-in-a-lifetime opportunity, even if he Wu Sangui has no new surrender, he has to force Wu Sangui to surrender to our dynasty and sacrifice Shanhaiguan, this is a once-in-a-lifetime opportunity, and it must not be missed. ”

"Then reply to Wu Sangui like this, agree to borrow troops, and when we arrive, we will force him to surrender, otherwise our army will take advantage of the defeat of him and Li Zicheng to wipe them out in one fell swoop." Fan Wencheng also suggested first.

Dolgon nodded, got up and said: "The discussion is over, don't delay any longer, pass down the military order: the third watch to make food, the fourth watch to set up the camp, go straight to Shanhaiguan, two white flags in front, and the other Manchurian, Mongolian, and Han banners are still unchanged according to the original marching sequence." After a pause, he added an order: "All the banners and horses must march lightly." Carry the heavy mules and horses, and then catch up! ”

Li Zicheng was slow to move against the Qing army, and only arrived at Shanhaiguan on 21 April, where he confronted Wu Sangui's troops on the west bank of the Shihe River. On the same day, Li Zicheng's Dashun army and Wu Sangui fought a vicious battle in Yibianshi and Xiluo City, and the Wu army won a small victory over Xiluo City, and then Li Zicheng's army stormed Dongluo and the two cities on the north flank.

Customs north by the corner mountain, south of the Bohai Sea, the city high wall is strong, outside the Luo City, the wing city is each other's horns, easy to defend and difficult to attack. In addition to Wu Sangui's department, the defenders also had 10,000 Gaodi troops and about 30,000 Xiangyong. On the day Li Zicheng arrived at the customs, he issued an ultimatum to Wu Sangui to force him to surrender, and after being refused, he ordered nearly 20,000 troops from Tang Tong and Bai Guangen to set up camp from a piece of stone to cut off Wu Sangui's retreat, and on the other hand, he attacked Xiluo, the northern flank, and Dongluo City with a main force of 60,000 respectively. Wu Sangui lined up with the main force on the line west of the Shihe River in Xiluocheng to prevent the Dashun army from attacking the fortifications. The two sides fought fiercely near the city of Xiluo, and in order to get out of the predicament, the defenders lured thousands of Dashun troops to approach the city walls, and artillery burst out on the city, and the Dashun army suffered many casualties and was forced to retreat. In the northern wing of the city, the Dashun army took advantage of the condescending terrain to storm the city wall, and fought fiercely until dawn the next day, forcing the defenders to surrender, but because the other cities were not taken, the Dashun army failed to enter Luocheng.

At this time, Dolgon led the army to the Shanhai Pass, knowing that the Dashun army was storming the Shanhaiguan, but adopted the strategy of waiting for work at ease and taking preemptive action, and wanted to wait for the Dashun army and Wu Sangui's troops to fight tiredly, highlighting the surprise soldiers to win in one fell swoop, so they always stood still, and sent someone to inform Wu Sangui that the soldiers did not borrow, and there was only one way to surrender.

In the early morning of April 20, the Qing army advanced to only two miles away from Shanhaiguan City, Wu Sangui saw that the situation was critical, and led a few light cavalry to break out of the siege, galloped to the Qing army camp of Weiyuan Fort in the east of Guancheng, and knelt down at Dolgon, who saw that Wu Sangui was obedient and not fraudulent, and accepted Wu Sangui's request, Dolgon ordered Wu Sangui to shave his head according to Manchurian customs, and promised to marry Princess Jianning, the princess of the emperor's Taiji daughter, to Wu Yingxiong, the son of Wu. And together with Shuoying King Azig and Doluo County King Duoduo led a strong army of 80,000 soldiers, and entered the Shanhai Pass without blood, making Wu Sangui's department the vanguard and attacking Li Zicheng.