越南阮朝開國者阮福映（1802－1819在位）因復國時曾得法人之助，在位時採取開放態度，法國傳教士未被排斥，但是明命帝（1820－1840在位）開始，便收緊對傳教士的活動、及至紹治帝（1841－1847在位）和嗣德帝（1848－1883在位）時，一律採行禁教，外國傳教士及本國教眾都受到迫害。法國藉口保護傳教士為由，開始對越南展開入侵的行動。1861年，法國趁參與第二次鴉片戰爭之餘威，一舉攻下南圻北三省（嘉定、邊和、定祥），在1862年迫使越南簽署〈壬戌和約〉。本文就是針對嗣德帝面對法國的入侵，希望通過外交接觸、談判及報紙公論來修改與法國簽訂的和約，企圖收回被占三省。但由於朝廷大臣多是保守的讀書人，包括嗣德帝本人，雖然能運用外交及公論手段來達到目的，但因自信過高及對和談代表潘清簡的不信任，結果修約談判變成嗣德帝的惡夢，不但收不回三省（嘉定、邊和、定祥），且把南圻南三省（永隆、安江、河仙）也賠掉了。本文就是分析及論述嗣德帝在簽約及修約談判過程中所扮演的角色，並對談判結果應負起完全的責任。

After the restoration and unification of Nguyen-phuc Anh in Vietnam in 1802, the Emperor Gai-long carried out an opening policy toward the western priests and other followers because of his receiving military help from the French priest Pigneau de Behaine during the restoration war. However, after the death of Nguyen-phuc Anh, the following Emperors such as Minh-mang, Thieu-tri and also the Younger Emperor Tu-duc carried out a strict policy of prohibiting Christianity activities. The strict policy aroused French ambition to conquer South Vietnam as a French colony in Far East in the name of protecting its people and Christian priests. In the year of 1861, the French Navy attacked Vietnam and conquered three provinces of Gia-dinh, Bien-hao and Dinh-turong which were in the north of Cochinchine. Therefore, Vietnam and France had signed the Treaty of Saigon in 1862. Actually, South Vietnam had been separated into two parts and the central government of Vietnam did not directly administrate the three southern provinces of Vinh-long, An-qiang and Ha-tien. Therefore, Emperor Tu-duc tried to make some means such as diplomatic activities, negotiation of renewal the treaty and using opinion of the west newspapers in order to force France to give back the captured areas. He appointed Phan Thanh-gian to visit France to negotiate with the French officer. In fact, Phan Thanh-gian had tried his best to convince France to renew the treaty of agreeing to return those three provinces. Nevertheless Emperor Tu-duc and -the high court officers did not trust the assigned negotiator Phan Thanh-gian. Ultimately, the negotiation of Viet-French became the nightmare of the Emperor. As a result, France changed its mind, and even conquered the remaining parts of Cochinchine. The purpose of this paper is to discuss and analyze how the Emperor Tu-duc conducted the negotiation and he ought to be responsible for the final result.