$Nguy{\tilde{\hat{e}}}n$ Cư Trinh has two faces in the history of territorial expansion of Vietnam into the Mekong delta. One is his heroic contribution to the $Nguy{\tilde{\hat{e}}}n$ family gaining control over the large part of the Mekong delta. The other is his role to make the eyes of readers of Vietnamese history be fixed only to the present territory of Vietnam. To the readers, $Nguy{\tilde{\hat{e}}}n$ Cư Trinh's achievement of territorial expansion was the final stage of the nam $ti{\acute{\hat{e}}n$ of Vietnam. In fact, however, his achievement was partial. This study pays attention to the King $V{\tilde{o}}$ instead of $Nguy{\tilde{\hat{e}}}n$ Cư Trinh in the history of the territorial expansion in the Mekong delta. King's goal was more ambitious. And the ambition was propelled by his dream to build a new world, and its order, in which his new capital, $Ph{\acute{u}}$ $Xu{\hat{a}}n$ was to be the center with his status as an emperor. To improve my assertion, three elements were examined in this article. First is the nature of $V{\tilde{o}}$ Vương's new kingship. Second is the preparation and the background of the military operation in the Mekong Delta. The nature of the new territory is the third element of the discussion. In 1744, six years after this ascending to the throne, $V{\tilde{o}}$ Vương declared he was a king. Author points out this event as the departure of the southern kingdom from the traditional dynasties based on the Red River delta. Besides, the government system, northern custom and way of dressings were abandoned and new southern modes were adopted. $V{\tilde{o}}$ Vương had enough tributary kingdoms such as Cambodia, Champa, Thủy $X{\tilde{a}}$, Hoả $X{\tilde{a}}$, Vạn Tượng, and Nam Chưởng. Compared with the $L{\hat{e}}$ empire, the number of the tributary kingdoms was higher and the number was equivalent to that of the Đại Nam empire of the 19th century. In reality, author claims, the King $V{\tilde{o}}^{\prime}s$ real intention was to become an emperor. Though he failed in using the title of emperor, he distinguished himself by claiming himself as the Heaven King, $Thi{\hat{e}}n$ Vương. Cambodian king's attack on the thousands of Cham ethnics in Cambodian territory was an enough reason to the King $V{\tilde{o}}^{\prime}s$ military intervention. He considered these Cham men and women as his amicable subjects, and he saw them a branch of the Cham communities in his realm. He declared war against Cambodia in 1750. At the same time he sent a lengthy letter to the Siamese king claiming that the Cambodia was his exclusive tributary kingdom. Before he launched a fatal strike on the Mekong delta which had been the southern part of Cambodia, $V{\tilde{o}}$ Vương renovated his capital $Ph{\acute{u}}$ $Xu{\hat{a}}n$ to the level of the new center of power equivalent to that of empire for his sake. Inflation, famine, economic distortion were also the features of this time. But this study pays attention more to the active policy of the King $V{\tilde{o}}$ as an empire builder than to the economic situation that has been told as the main reason for King $V{\tilde{o}}^{\prime}s$ annexation of the large part of the Mekong delta. From the year of 1754, by the initiative of $Nguy{\tilde{\hat{e}}}n$ Cư Trinh, almost whole region of the Mekong delta within the current border line was incorporated into the territory of $V{\tilde{o}}$ Vương within three years, though the intention of the king was to extend his land to the right side of the Mekong Basin beyond the current border such as Kampong Cham, Prey Vieng, and Svai Rieng. The main reason was $V{\tilde{o}}$ Vương's need to expand his territory to be matched with that of his potential empire with the large number of the tributary kingdoms. King $V{\tilde{o}}^{\prime}s$ strategy was the variation of 'silkworm nibbling' and 'to strike barbarians by barbarians.' He ate the land of Lower Cambodia, the region of the Mekong delta step by step as silkworm nibbles mulberry leave(general meaning of $t{\acute{a}}m$ thực), but his final goal was to eat all(another meaning of $t{\acute{a}}m$ thực) the part of the Mekong delta including the three provinces of Cambodia mentioned above. He used Cham to strike Cambodian in the process of getting land from Long An area to $Ch{\hat{a}}u$ Đốc. This is a faithful application of the Dĩ Man $C{\hat{o}}ng$ Man (to strike barbarians by barbarians). In addition he used Chinese refugees led by the Mạc family or their quasi kingdom to gain land in the region of $H{\grave{a}}$ $Ti{\hat{e}}n$ and its environs from the hand of Cambodian king. This is another application of Dĩ Man $C{\hat{o}}ng$ Man. In sum, author claims a new way of looking at the origin of the imperial world order which emerged during the first half of the 19th century. It was not the result of the long history of Đại Việt empires based on the Red River delta, but the succession of the King $V{\tilde{o}}^{\prime}s$ new world based on $Ph{\acute{u}}$ $Xu{\hat{a}}n$. The same ways of Dĩ Man $C{\hat{o}}ng$ Man and $T{\acute{a}}m$ Thực Chi $K{\acute{\hat{e}}}$ were still used by $V{\tilde{o}}^{\prime}s$ descendents. His grandson Gia Long used man such as Thai, Khmer, Lao, Chinese, and European to win another man the '$T{\hat{a}}y$ Sơn bandits' that included many of Chinese pirates, Cham, and other mountain peoples. His great grand son Minh Mạng constructed a splendid empire. At the same time, however, Minh Mạng kept expanding the size of his empire by eating all the part of Cambodia and Cham territories.