Wu Sangui Admits the Qing Army Through the Pass

Timeline

1. 1644Shanhaiguan · North ChinaAfter the fall of Beijing, Wu Sangui led the Guanning army in holding Shanhaiguan; he at one point considered submitting to the Dashun, but the Dashun forces detained his family in the capital and pressed him to surrender, prompting Wu Sangui to change his stance.
2. 1644Shanhaiguan · North ChinaWu Sangui wrote to the Qing regent Prince Dorgon seeking aid; Dorgon led the Eight Banners westward from Ningyuan, and Wu Sangui opened the pass to admit the Qing army, the two sides forming a military alliance.
3. 1644Shanhaiguan area · North ChinaLi Zicheng personally led the Dashun army eastward in pursuit of Wu Sangui; the allied Qing and Guanning forces met them outside Shanhaiguan, and the Dashun army was decisively defeated. Li Zicheng retreated to Beijing, and the Qing army was able to drive straight into the Central Plains.