1862年越法簽訂〈壬戌和約〉後，嗣德帝企圖通過修約談判，希望贖回割讓的土地，可是他失敗了。法國在1867年趁勢把南圻全境占領。當時越南未承認法人占領的事實，一直沒有與法國簽訂新約，直至1874年才與法國簽訂〈甲戌和約〉，承認法人占領南圻。本文的研究重點在分析嗣德帝為何在1874年願意與法國簽訂和約，並論述及分析嗣德帝簽訂和約後，企圖以自主外交擴大越南的國際空間，希望藉此擺脫法國的羈絆，尋找越南的國際地位。當嗣德帝企圖走出法國的掣肘時，他才清楚的認知在西方條約體系下，表面的尊重只是一種文字遊戲，對弱勢者而言條約就好像一把利劍橫架在脖子上。在法國的千般阻撓下，越南的企圖失敗了。為了阻止法人繼續北侵，嗣德帝又回到傳統的朝貢體系下，尋求清廷的保護。

The intention of the Emperor Tu-duc in Vietnam to redeem the ceded territory by the way of reforming old treaty finally failed after the French occupied the rest of Coch-China in 1867. The Vietnamese did not admitted the fact until 1874 when the government signed the treaty of Sigon with the French. The focus of this article is to analyze the reason why the Emperor Tu-cuc signed the Treaty of Saigon in 1874. In addition, how the Emperor expanded Vietnam's surviving space and raised its international status after he signed this treaty are also parts of this discourse. The Emperor eventually returned to the traditionally tributary protection by China after he realized that the international treaty system was just like a sword putting on the neck of a weak nation such as Vietnam.