Wu Sangui lends Qing troops

In 1644 A.D., Li Zicheng formally established his regime in Xi'an with the state name Da Shun. Then, Li Zicheng led one million rebel soldiers to cross the Yellow River and attacked Beijing in two ways. The two armies were so powerful that they met under the city of Beijing in March of that year. The three most elite battalions of the Ming army stationed outside the city all surrendered.

The uprising army stormed Beijing. The next night, Emperor Chongzhen climbed up Coal Hill (behind the imperial palace, now Beijing Jingshan) and looked around, only to see the fire reflected in the sky. After waiting for a long time, there was no one in sight. Only then did he realize that the end was near and returned to the coal mountain, where he hanged himself under an acacia tree by the Shouhuang Pavilion. The Ming Dynasty, which had ruled China for two hundred and seventy-seven years, was declared extinct.

The Datsun insurgent army broke through Beijing, and the general Liu Zongmin led the procession into the city first, followed by Li Zicheng, the king of Dasun, wearing a hat and green cloth, straddling a steed, and slowly entering the Forbidden City. The people of Beijing welcomed the uprising army with lights and colors as if it were a festival.

The Datsun regime issued a list of people to live and work in peace; on the other hand, they severely punished the Ming Dynasty's royal relatives and corrupt officials. Li Zicheng sent Liu Zongmin and Li over and ordered those powerful people to hand over the money they usually scraped from the people, as the military paid for the uprising army, and refused to deliver a heavy sentence. A few imperial relatives with great public anger were arrested and killed by the insurgents.

A big bureaucrat, Wu Xiang, had his family property raided by Liu Zongmin and was arrested to recover the loot. Someone told Li Zicheng that Wu Xiang's son, Wu San Hang, was the chief soldier of the Ming Dynasty's Shanhaiguan and had hundreds of thousands of troops under him. If Wu Sangui was recruited and surrendered, it would not be a threat to the Dasun regime.Li Zicheng thought the idea made sense and asked Wu Xiang to write to his son to persuade him to surrender to the rebel army.

Wu Sangui was originally sent by the Ming Dynasty to fight the Qing Dynasty outside of China and was stationed in the area of Ningyuan for defense. When the uprising army was approaching Beijing, Emperor Chongzhen gave orders to Wu Sangui to bring troops into the customs to deal with the uprising army. Wu Sangui arrived at Shanhaiguan, Beijing had been overrun by the uprising army. After a few days, Wu Sangui received a letter from Wu Xiang to persuade him to surrender, but hesitated. He was reluctant to surrender to the rebel army, but if he didn't, the rebel army was so brave and powerful that he was no match for them. Besides, there are still his family possessions in Beijing, and he can't afford to lose them. Since Li Zicheng was invited to surrender, why not go to Beijing to see the situation before?

Wu Sangui led his troops to Lanzhou, closer and closer to Beijing, they met some people who had escaped from Beijing. Wu Sangui found a question, at first, heard that his father Wu Xiang was captured, the family fortune was copied, already hate gnashing teeth; then, heard that his favorite singer Chen Yuan Yuan was also captured by the rebel army, and angrier, immediately ordered to return to the Shanhai Pass, and asked the soldiers to change into white helmets and white armor, said to avenge the dead Chongzhen Emperor.

Li Zicheng learned that Wu Sangui refused to surrender and decided to personally bring more than 200,000 troops and attack the Shanhai Pass. Wu Sangui was already afraid of the peasant army, and when he heard the news, he was scared out of his soul. He couldn't care less about his national integrity, wrote a letter, and sent his men flying out of the customs to ask the Qing Dynasty to help him suppress the rebellion.

Qing Dynasty Prince Dorgon received Wu Sangui's letter of help, felt that the opportunity came, and immediately wrote back to agree. Then, he led more than 100,000 Qing troops, day and night to the Shanhai Pass.

The Qing army arrived at the Shanhai Pass, Wu Sangui has been eager to greet Dorgon with 500 of his soldiers out of the customs. He met with Dorgon and begged Dorgon to help him take revenge. Dragon naturally agreed to go along with it. Wu Sangui invited Dorgon into the pass, hosted a banquet, killed the white horse and cattle, worshipped heaven and earth, and entered into an alliance.