Everyone knows that the node of the war between the Ming Dynasty and the Qing Dynasty was that Wu Sangui opened the gate of Shanhaiguan and led troops into the customs. Why, then, did Wu Sangui choose to surrender to the Manchus?
It can be said that Wu Sangui was loyal to the Ming Dynasty in the first half of his life, Wu Sangui has been trained in the barracks since he was a child, and he fought with the Qing army in Jinshan, and both sides suffered casualties, showing his military talent.
Huang Taiji wanted to plot against Wu Sangui and sent him a letter, although Wu Sangui did not surrender to the Qing Dynasty, but he had already begun to hesitate.
The Qing army fought more and more fiercely, causing Ningyuan, where Wu Sangui was located, to become a lonely city outside the Shanhai Pass.
In 1644 of the Ming Dynasty, the Dashun army pointed directly at the Beijing Division, and Emperor Chongzhen summoned the world's benevolent and righteous teacher King Qin, but it was still to no avail, and finally hanged himself.
At this time, Wu Sangui seemed to have lost his backbone, and the Ming Dynasty, who had always been loyal, had perished at this time, and where should he go. Li Zicheng has recruited Wu Sangui many times, but Wu Sangui is hesitating, and later it is said that Wu Sangui's concubine Chen Yuanyuan was taken away by Li Zicheng.
Therefore, Wu Sangui could only pretend to surrender to Li Zicheng, negotiate peace with him, and ask Dolgon for help in private. Wu Sangui and Dolgon conspired, causing Li Zicheng to delay the opportunity to seize Shanhaiguan, and the Qing army entered the customs.
Because of the situation that Wu Sangui was in at that time, Li Zicheng's power was quite large, and his family was in the hands of Li Zicheng, threatening Wu Sangui. He could only choose the side with more ability and strength, coupled with Dolgon's persecution, he took advantage of Wu Sangui's hesitation and successfully made Wu Sangui surrender to the Qing army. Therefore, they united to defeat Li Zicheng's army.
(The picture comes from the Internet)