Thiệu Trị
Trị's determination to eliminate all Roman Catholic missionaries from his country could not be reconciled with a peaceful relationship with France. In 1845, this almost prompted a clash between Vietnam and the American warship "USS Constitution" which attempted to force Trị to free the missionary Dominique Lefèbvre, who had repeatedly come to Vietnam illegally multiple times. The French task force reached Tourane on 23 March 1847, and demanded that the safety of French nationals be assured and for Thiệu Trị to cease the persecution of missionaries.