In the course of this successful venture into colonialism (for it was nothing else), the Vietnamese state decided to institutionalize the process, and in 1481, the don-dien were created. Like the Roman coloniae 1500 years earlier or the Israeli nakhal settlements 500 years later (or the Austro-German Wehrbauern in the 1700's) the don-dien were agricultural settlements given to farmers who were for the most part army veterans and who, in return for free land, defended the new frontier. The members of the don-dien were a tough hardy lot, not only willing to defend what they already had, but usually not loath to push the border farther west-this time at the expense of the decaying Khmer (Cambodian) state. It was obvious such a situation was fertile in border incidents, which were further exploited to round out the Vietnamese domain. In 1658, all of South Viet-Nam north of Saigon (then that the fishing village of Prey Kor) was in Vietnamese hands; Saigon itself fell in 1672.
Excerpt from “The Two Viet-Nams: A Political and Military Analysis”, Chapter 2: A Glimpse of the Past
By Bernard B. Fall (Praeger Publishers, New York, 1971), pp 10-19
In 111 B.C., the victorious Han crushed the young Vietnamese state, and save for a few brief but glorious rebellions, it remained a Chinese colony for more than 1,000 years.
Viet-Nam became a Chinese protectorate ruled by a governor and subdivided into military districts. By the beginning of the first century A.D., the country had absorbed along with many Chinese settlers – a great many of them the refugees from the Han dynasty – much of what was worthwhile in the culture of the occupying power: the difficult art of rice planting in artificially irrigated areas, Chinese writing skills, Chinese philosophy, and even Chinese social customs and beliefs. But – and in this the Vietnamese are unique – they succeeded in maintaining their national identity in spite of the fact that everything else about them had become “Chinese.” Opposition to the Chinese rule built up as the Chinese presence became more ubiquitous and brutal. Finally, what could be called a routine “occupation incident,” the execution of a minor feudal lord, brought about a configuration. In 39 A.D., Trung Trac, the wife of the slain lord, and her sister Trung Nhi raised an army that, in a series of swift sieges, overwhelmed the Chinese garrisons, which had grown careless over the years. In 40 A.D., the Vietnamese, much to their surprise, found themselves free from foreign domination for the first time in 150 years and the Trung sisters were proclaimed queens of the country.
Naturally in so large an empire, Chinese reaction was slow, but when it came, it was effective. Old general Ma Yuan began his counterattack in 43 A.D., and the Vietnamese troops of the two queens made a fatal error: They chose to make a stand in the open field against the experienced Chinese regulars, with their backs against the limestone cliffs at the edge of the river Day – not far from the place where General Vo Nguyen Giap was to pit his green regulars against French Marshal de Lattre’s elite troops 1,908 years later.
The result was the same in both cases: The more experienced regulars destroyed the raw Vietnamese levies. The two queens, rather than surrender to the enemy, chose suicide by drowning in the nearby river. “Sinization” now began in earnest, with Chinese administration taking the place of traditional leaders. Two more rebellions took place. One in 248 A.D., also led by woman, Trieu Au, collapsed almost immediately, and like the Trung sisters, Trieu Au committed suicide. The second led by Ly Bon lasted from 544 to 547 and was also crushed. With the rise of the strong Tang dynasty in China after 618, resistance became hopeless: Viet-Nam became the Chinese Protectorate General of the "Pacified South" ("An-Nam" in Chinese). It was under the name "Annam," a symbol of humiliation and defeat that the region was to become best known to the outside world.