袁崇焕
The last decades of the Ming saw famines, floods, economic chaos, rebellions, and invasions. In 1618, the upstart Jianzhou Jurchen leader Nurhaci united the tribes of Manchuria and declared war on the Ming. After the Fushun garrison within the Liaodong Wall surrendered to Nurhaci the next year, the Ming court assembled a Chinese–Korean army numbering above 100,000 men to contain him, but they were catastrophically defeated at the Battle of Sarhu. Nurhaci made substantial progress in his conquest of Liaodong until he was mortally wounded at the 1626 Battle of Ningyuan by Yuan Chonghuan. He was succeeded by his son Hung Taiji, who worked to undermine Yuan Chonghuan by spreading rumours of Yuan's collaboration with the Jurchens. To drive the point home, Hung Taiji sent an army around Ningyuan through Mongol territories to breach the Great Wall pass at Xifengkou in the fall of 1629, taking advantage of a rift in the Ming ranks due to Yuan Chonghuan's execution of his fellow commander Mao Wenlong. This breach, known as the Jisi Incident, was the first time the Jurchens had broken through the Great Wall into China proper since the troubles in the northeast began. Yuan Chonghuan hastily sent an army to drive off the raiders from the walls of Beijing, but political damage had already been done. Yuan Chonghuan was accused of treason for letting this happen, and in 1630 he was executed by slow dismemberment while his family were exterminated or exiled.