Phương had risen quickly in military ranks after recapturing Hà Tiên and defeating the Siamese army at Châu Đốc. He succeeded Trương Minh Giảng in 1841 as viceroy of Thiệu Trị (reigned 1841–1847) in Southern Cochinchina. He then became a senior advisor to the next emperor Tự Đức (reigned 1847–83). He was wounded and captured by the French in 1873. He refused to be treated by French and began a hunger strike, dying shortly afterwards. His ceremonial dress was taken as a trophy by Francis Garnier.