When the Tay Son rebellion overthrew Le Chieu Thong, the Chinese Emperor, Qianlong, saw it as both his duty to restore the legitimate ruler as well as an opportunity to expand the Great Qing Empire, which was at its peak during his reign. However, as had often happened in the past, the Chinese were defeated and driven out of Viet Nam by Nguyen Hue. Afterwards though, peace was restored and the relationship between Hanoi and Peking continued in the traditional way. The situation did improve further in 1802 with the enthronement of Emperor Gia Long and the start of the Nguyen dynasty.
Gia Long was an admirer of China, and it was his goal to use the methods proven in China to build a strong and stable empire that could withstand the test of time. In the early part of the Nguyen reign China was the first example for the establishment of the new government. Everything from building style, the Imperial City in Hue, court costumes and Confucian ethics were inspired by Ming Dynasty China. The civil service and legal code were almost exact copies of those used by the Qing Empire at that time. Emperor Gia Long wanted to use Chinese methods, but also surpass them. He wanted an empire with more mandarins working in the populace, stricter adherence to the Confucian principles and to the rites of the various religious beliefs.
Throughout the reign of Gia Long there developed a division among the court which had been described as a French faction, focused around the family of Crown Prince Canh (who had visited France as a boy) and the French officials Gia Long had appointed since the war; and a Chinese faction which was focused on the Confucian mandarins and Prince Nguyen Phuc Dam (later Emperor Minh Mang). Eventually, the encroachment of France pushed Gia Long to favor the Chinese camp and name Prince Dam as his successor. The Chinese sent an imperial seal for the use of the Emperor and the Qing ambassador was always treated as the first guest in importance in the country. Throughout the reigns of Minh Mang, Thieu Tri and Tu Duc, Vietnam drew closer to China, which despite being an ancient enemy was nonetheless the cultural forefather of the country. Tribute was paid and humble language used, but this did not bother the Nguyen in the least as China never attempted to directly control their country. The humiliation of China in the Opium War shocked Vietnam and encouraged the Nguyen to adopt a more defensive and isolationist foreign policy.
The arrival of France considerably complicated the situation however. Access to southern China was the primary purpose behind the French invasion of Vietnam and when it became clear that Vietnam would be defeated, Emperor Tu Duc called on the Qing Empire for assistance. Chinese troops moved into northern Vietnam and the result was the Sino-French War and a period of chaotic conflict in the Tonkin region. Ultimately however, the French were victorious and forced China to recognize France as the "protector" of Vietnam. Furthermore, the French destroyed the Imperial seal from China and forced the Vietnamese to make a new one in recognition of the fact that they now had a new master.
