"Weeping in mourning, the three armies are all in plain clothes, and being angry makes beauty beautiful", a famous saying from Wu Meicun, a poet in the late Ming and early Qing dynasties, refers to the events of Wu Sangui and Chen Yuanyuan. Li Zicheng besieged Beijing, but Wu Sangui first surrendered and revolted. "History of the Ming Dynasty" records: "At the beginning, Sangui was ordered to come in for reinforcements. When he arrived at Shanhaiguan, the capital was trapped and he hesitated to advance. Zicheng robbed his father Xiang and wrote a letter to recruit him. Sangui wanted to When he arrived in Luanzhou, he was very angry when he heard that his concubine Chen Yuan was captured by Liu Zongmin.

In the spring of 1644, the strategic location of Shanhaiguan became particularly important. The Dashun Army captured Beijing, and Li Zicheng seemed to have conquered the Central Plains. At this time, Sanhaiguan was guarding the throat of the Qing army entering the customs. The guard Wu Sangui had a heavy army and was an elite force among the Ming Dynasty's border guards. Wu Sangui's decision was of great importance to the situation in North China at that time. If Wu Sangui turns to Li Zicheng and restrains the Qing army from going south, then the Dashun army will basically complete the pacification of the north, and then it will be just around the corner to send troops south, drink from the Yangtze River, and dominate the world. In fact, Li Zicheng only brought a small number of troops with him when he entered Beijing, while a large number of elite troops were deployed in Shanxi, Shaanxi, and Hubei, preparing to pacify the south in one fell swoop after capturing Beijing and demarcating the north.

At this moment, Wu Sangui's rebellion did not attract enough attention from Li Zicheng. Li Zicheng did not expect that Wu Sangui would collude with the Qing court and lead the Jin soldiers into the Central Plains. The counter-insurgency work was therefore very sloppy. Only 100,000 troops who entered Beijing were brought to Shanhaiguan, and no elite troops were mobilized from the west to join the battle of Shanhaiguan. In terms of military strength alone, Wu Sangui's army of 50,000 was obviously at a disadvantage against Li Zicheng's army of 100,000. However, due to the danger of the pass and the fact that the Shanhaiguan garrison itself was a capable soldier, it could also resist stubbornly. This is indeed the case. On May 18, Li Zicheng and Liu Zongmin led the Dashun Army to send troops to the capital, with their troops directed at Shanhaiguan. On May 26, the Dashun Army arrived at Shanhaiguan, surrounded Wu Sangui, and began to attack Shanhaiguan. If nothing happens, Shanhaiguan can be launched soon. The situation changed dramatically the next day. On May 19, Dorgon threw all the country's elite troops into battle. The Dashun army was defeated and corpses were everywhere. "Manuscripts of the History of the Qing Dynasty" records this incident, "Zicheng led a crowd of more than 200,000 people, stretching from Beishan to the sea, and prepared a strict formation. That day, there was a strong wind, and the sky was covered with dust and sand. Prince Rui Dorgon ordered to attack the rear of the formation, with Sangui He was on the right wing and shouted loudly. The wind swirled and the rebels were defeated. They chased for more than 40 miles and returned to Yanjing. (Note: The number of "two hundred thousand" for Zicheng's army is not correct. According to Gu Cheng's research, it is ten. Wan.)

Wu Meicun, the former poet, was a survivor of the Ming Dynasty. He was ranked second in the rankings at the age of twenty-three. Emperor Chongzhen was kind to him. After entering the Qing Dynasty, he became a second minister. He suffered a lot in his later years. I have a lot of regrets about the mountains and rivers. The first two sentences of this article are really incomprehensible. "Three armies are in full bloom" refers to Wu Sangui's army guarding the festival for his father Chongzhen. The reason for raising the army is "to avenge his father", which is natural for kings and ministers; and "to get angry" is specifically for Chen Yuanyuan. From then on, he surrendered and then rebelled against the Dashun regime. He was capricious and had no courtesy at all. According to the history, after Wu Sangui rebelled against the Dashun Peasant Army, he devoted himself to the Qing court, forgetting the righteousness of the world for his own selfish interests, and caused China to fall into the hands of the Yi Di. Wu Sangui was the first to take the blame. This sentence of Wu Meicun is not intended to be confusing, but actually contains an ironic meaning.

Of course, blaming all the Shanhaiguan defeat on Wu Sangui seems to be too harsh. We might as well apply Bradley's famous saying about the United States' participation in the Korean War. The Dashun Army "fought the wrong battle with the wrong enemy at the wrong time and in the wrong place!" However, this was not a "wrong war". Wrong enemies”, but “two wrong enemies”. However, history cannot be taken for granted.