It was during the reign of Emperor Tu Duc that the era of monarchial independence ended and the era of French colonialism began. Himself, Tu Duc was a highly educated man, renowned as the greatest classical scholar in East Asia. However, the country remained somewhat unstable, uprisings were a constant problem and international pressure, mostly from France, was increasing. Tu Duc intended to deal with this problem, but tried to do so at a time when France would be unable to respond.
          In 1848, when France and the rest of Europe, were in the midst of liberal revolution, Emperor Tu Duc began a new campaign against foreigners and Christians in Vietnam. He wrote, "
These barbarians enter every land without fear nor weariness; they conquer all peoples, regardless of expense. What is their aim here, if not to seize the land and poison it with their perverse doctrines? ....Therefore, we must not make peace with them, neither must we wage war but hold ourselves on the defensive, and to do that we must surround ourselves with obstacles". However, Tu Duc had seriously mistaken the attitude of France, and retribution was to be swift and brutal.
         The French were ready to focus on Vietnam much sooner than anyone in Hue thought possible. Emperor Napoleon III was eager to expand his territory and win the glory of his famous uncle, and the Empress Eugenie saw herself as a protector of the Church and deeply sympathized with the martyred Christians in Vietnam. Yet, two things must also be kept in mind. Much like the Qing dynasty in China, after whom the Nguyen took so much of their example, the persecution of Christians did not apply to high-placed converts, or those who were deemed too valuable to be without. Likewise, on the French side, there was a great deal of independent and often unauthorized action on the part of local military commanders, anxious to grab any territory in the colonial race against the British.
          Ultimately, France did strike back and did so with considerable force. The Vietnamese though, did manage to put up a spirited resistance with a military which the Emperor had recently reorganized. The French were not prepared for the Vietnamese climate and many died behind their fortifications from heat and disease. However, they still had their enemies outmatched in firepower, technology and above all disciplined organization to accomplish the goal at hand. Even now, the Nguyen Dynasty was still plagued by internal unrest. In the preceding years there had been around 500 minor to moderate rebellions and uprisings against the dynasty, all of which were defeated, but took considerable time and attention. When another rebellion broke out just as the French were gaining ground, Tu Duc became hopeless and called upon his nominal overlord, the Qing Emperor of China, for help. It was a desperate act, but by the late 1850's Tu Duc was very desperate.
         In the Franco-Chinese war that followed, centered around Hanoi in north Vietnam, the French were again victorious and forced China to recognize them as the masters of "the Great South". Emperor Tu Duc felt he could resist no longer and came to terms with France, giving up south Vietnam to Paris, which became the French colony of Cochinchina, and sending the venerable mandarin Phan Thanh Gian to work out the details. When Phan Thanh Gian arrived in Paris for his audience with the French imperial couple he was reverent, humble and meek, even going so far as to kowtow to the foreign rulers, which absolutely no Frenchman would ever lower himself to doing to the Emperor of Vietnam. This act impressed the compassion of Empress Eugenie and the notions of chivalry of Napoleon III, who then decided to take a softer approach in dealing with the Vietnamese. Sadly however, this policy was not to last long.
         Over time, the demands of the French, and the liberties taken by their forces and officials in Vietnam grew larger and larger. To make matters worse, the Vietnamese were lacking a strong voice of leadership. In July of 1883, at the age of 56, after 35 years on the throne, the longest reign of any Nguyen dynasty emperor, Tu Duc died, according to his attendants, cursing the French with his final breath. The French did not keep within the limits of the agreements and Phan Thanh Gian committed suicide after pledging his sons to fight the French for the rest of their lives. To make matters worse, due to an illness early in life, Tu Duc was unable to have children and a succession crisis followed after his death concerning three nephews he adopted, three regents he appointed and the ladies of the court harem. First to be enthroned was Emperor Duc Duc, but after only three days of nominal rule he was deposed and killed by the regents on grounds of depravity and failure to adhere to Confucian tradition.
         Next, the regents and Empress Dowager Tu Du enthroned the older Prince Nguyen Hong Dat as Emperor Hiep Hoa. At over thirty years old, he could see who held real power in Hue and was reluctant to accept, but was persuaded finally by the Empress Dowager to ascend the Golden Throne. However, Hiep Hoa soon clashed with the regents and powerful court mandarins. There was also an attack by the French navy on the Vietnamese coast. Hiep Hoa was warned that he must accept the role of a French "protectorate" or he and his dynasty would be totally destroyed.
          Seeing no alternative, Hiep Hoa signed a treaty which recognized France as "protector" and surrendered to Paris all rights of defense and foreign relations. To many, for the Emperor to give up any of his power to another entity was nothing less than the revocation of the "Mandate of
Heaven". Ton That Thuyet, the most powerful of the three regents, insulted the Emperor to his face and refused to prostrate himself in his presence. Emperor Hiep Hoa felt a coup coming on and, perhaps fearing the same fate Emperor Duc Duc had suffered at the hands of the regents, he went to the only force he felt he could turn to for safety against his officials -the French. Here, he was firmly placing his position and person in the hands of France. However, it was not enough to save him. When Thuyet found out, in an unprecedented action, he had the Emperor himself arrested on November 28, 1883.
          Charged with wasting public funds, ignoring the advice of his officials and of selling out to a foreign power by signing the Harmond Treaty, Hiep Hoa was forced to kill himself the following day after reigning for only six months. With his death, the final end had come to Viet Nam as an independent monarchy. The era of French colonialism in Indochina had begun.