 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.