Thirdly, the state of Vietnam under Nguyen Dynasty: The Hoang Sa and Bac Hai Flotillas were assigned to exploit and safeguard Hoang Sa and Truong Sa archipelagoes. In July 1803, King Gia Long re-established Hoang Sa Flotilla and asked captain Vo Van Phu, Chief of Sa Ky seaport to recruit people from other localities to form the Hoang Sa Flotilla (according to the “Dai Nam Thuc Luc”, Vol. 12, the first year of Gia Long reign). In January 1815, King Gia Long decided to send Pham Quang Anh of Hoang Sa Flotilla to set off for Hoang Sa to survey sea route” (according to “Dai Nam Thuc Luc”, Vol. 50, page 6a, the first year of Gia Long reign).
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China has no legal basis to claim sovereignty over Hoang Sa, Truong Sa -- Vietnam+ (VietnamPlus)