Understanding the worsening health situation of King Tu Duc, in a letter sent to the Governor General of the South on December 10.12.1882, XNUMX, Resident General Rheinart wrote: "There is a very important point to pay attention to, that is, after King Tu When Germany died, we (the French side) had to be the ones to execute the king's will. This event will be extremely important for us (France), but it will be very difficult for us in the role of executors of the will, we must take away such status (execution of the will) from hands of the great mandarins (of the Hue court)".
According to the work Treasures of Hue Citadel after the fall of the capital by Francois Thierry (translated and written by translator Le Duc Quang and afterword, published by Thai Ha Books and Hanoi Publishing House): “Commander Rivière arrived in Hanoi on April 2.4.1882, XNUMX. The French campaign caused great insecurity to the Hue court. In addition, King Tu Duc's health condition had been serious for many months. Minister Nguyen Van Tuong immediately suggested many possibilities to pacify the French, in particular he suggested disarming Hanoi. In fact, while Rheinart was negotiating with Nguyen Van Tuong, Vietnamese forces were consolidating a defensive fort that was considered to be of extremely high caliber at Thuan An port.
The worrying thing is that while everything is "burning hot oil", the king is seriously ill. There has been no final decision on who to succeed. “Since three months ago, the King of Annam has had edema all over his body and is bedridden. On July 17.7, the king summoned three great ministers of the cabinet. Mr. Tran Tien Thanh, Nguyen Van Tuong and Ton That Thuyet to announce the king's will about his successor," the book cited.
Why think of Ung Dang but King Tu Duc chose Prince Ung Chan?
According to author Francois Thierry: "At first the king thought that Ung Dang, a nephew and adopted son of the king, would be capable of assuming the kingship, but then he realized that he was too young to hold the kingship. dynasty, in a difficult situation with the events that were taking place in July 7.1883. The king had to turn to designate his successor as one of his other adopted grandchildren, Prince Nguyen Phuc Ung Chan, whose other name according to his private residence is Duc Duc. This latter character is not the right person at the right time, because he has an easy-going lifestyle with many flippant behaviors... But Duc Duc has the advantage of being 34 years old, and the kingship is in need of a senior king. wall".
Finally, before his death, King Tu Duc also arranged for his successor, Duc Duc. King Duc Duc also received spiritual support from Queen Mother Tu Du - King Tu Duc's mother and First Queen Trang Y, to be able to avoid unpredictable dangers during an uncertain transition period. Therefore, the king also assigned the chief mandarins such as Tran Tien Thanh, Nguyen Van Tuong and Ton That Thuyet along with prince Tho Xuan and prince Tuy Ly to become supervisors of the Royal Council.
In the hereditary decree, there is a passage where the king worriedly wrote: "Ung Chan has a defect in his eyes, so his actions are shady. He is afraid that in the future he will not be clear-headed, considering that lust is also not a good thing, he may not be able to handle it." big deal. A country with an elderly king is a good thing for the commune, if we leave, what will we do?" (Nguyen Phuc family genealogy, 1995, p. 371).
Also according to the book Treasures of Hue Citadel after the fall of the capital by Francois Thierry, at this time King Tu Duc assigned Mr. Hoang Ta Viem full military command in the North, promoting him to the position of President of the Northern Military Service. On July 19.7.1883, XNUMX, King Tu Duc passed away, ending his days of painful struggle with illness and also worrying about his successor.