Qing China invaded Vietnam to reinstall the deposed emperor Lê Chiêu Thống. Ngô Văn Sở ordered Cận to write a letter to the Qing viceroy Sun Shiyi. Cận described himself as a popular ruler and tried to persuade Sun to retreat. But it was rejected by Sun. On 22 December 1788, Nguyễn Huệ proclaimed himself emperor Quang Trung and formally declared that the Lê dynasty had ended. Huệ then led an army march north, defeated the Qing army, and banished Lê Chiêu Thống again. Cận's name was not mentioned in the later history records.