西貢條約
Despite his prominent position in the Nguyễn Dynasty, little is known about Phan's personal stance on Vietnamese relations with France, which was in the process of colonising Vietnam. France had first invaded in 1858, beginning the colonisation of southern Vietnam. Three provinces were ceded under the 1862 Treaty of Saigon, and a further three in 1867 to form the colony of Cochinchina. During the period, there was debate in the Huế court on the best strategy to regain the territory. One group advocated military means, while another believed in the use of diplomacy in addition to financial and religious concessions. By the time of Tự Đức's death in 1883, the whole of Vietnam was colonised, henceforth incorporated with Laos and Cambodia into French Indochina.