Born in Thai Binh province in northern Vietnam, he completed his primary and secondary studies at the Collège du Protectorat and at the Lycée Albert Sarraut in Hanoi. He then graduated from the École des hautes études indochinoises in Hanoi and joined the mandarinate in Thai Binh province. He became a magistrate in Ha Dong province and assumed the post of president of the Tribunal at Nam Dinh, then Hung Yen. When the Viet Minh took power in mid-August 1945, he resigned his position as provincial governor of Thai Binh, which he had held since the Japanese coup de force of 9 March 1945. He was hostile to French attempts to rebuild their colonial state in Indochina but distrustful of Vietnamese communist intentions in the Democratic Republic of Vietnam (DRV). Though he briefly served as director of the cabinet of the minister of the Interior in the DRV in late 1945, he was a member of the Greater Vietnam Nationalist Party (Dai Viet Quoc Dan Dang). He refused to take part in the Bao Dai Solution, disappointed by the French refusal to grant real independence to non-communist Vietnamese. He agreed, however, to serve as governor of North Vietnam on two occasions as part of the emerging Associated State of Vietnam (between July 1949 and April 1951 and again between November 1952 and July 1954). He accepted the post of minister of Defense in the second cabinet of Tran Van Huu, constituted on 18 February 1951. He was an energetic and capable administrator, non-communist, and no French stooge.