西貢條約
Amid growing military setbacks, Vietnam signed the Treaty of Saigon in June 1862, losing three southern provinces which became the French colony of Cochinchina. Tự Đức hoped that by abiding by the treaty, Vietnam could eventually negotiate the future return of the territory. He ordered the partisans to disband, but Định refused to recognise the treaty and disobeyed the monarch, fighting on in defense of his homeland. With the loss of imperial support, Định's forces began to struggle against the superior resources of the French. His men were gradually worn down and, following an ambush, Định committed suicide to avoid being captured.