The Empire of Vietnam (; Literary Chinese and Contemporary Japanese: ; Modern Japanese: ) was a short-lived puppet state of Imperial Japan governing the former French protectorates of Annam and Tonkin between March 11 and August 25, 1945. At the end of its rule, the empire also successfully reclaimed Cochinchina as part of Vietnam. History During World War II, after the fall of France and establishment of Vichy France, the French had lost practical control in French Indochina to the Japanese, but Japan stayed in the background while giving the Vichy French administrators nominal control. This changed on 9 March 1945 when Japan officially took over. To gain the support of the Vietnamese people, Imperial Japan declared that it would return sovereignty to Vietnam. On 11 March 1945, Emperor Bảo Đại was permitted to announce the Vietnamese "independence", this declaration had been prepared by Yokoyama Seiko, Minister for Economic Affairs of the Japanese diplomatic mission in Indochina and later advisor to Bảo Đại Bảo Đại declared the Treaty of Huế made with France in 1884 void. Trần Trọng Kim, a renowned historian and scholar, was chosen to lead the government as prime minister. Policies Constitutional issues Kim and his ministers spent a substantial amount of time on constitutional matters at their first meeting in Huế on 4 May 1945. One of their first resolutions was to alter the national name to Việt Nam. This was seen as a significant and urgent task. It implied territorial unity; "Việt Nam" had been Emperor Gia Long's choice for the name of the country since he unified the modern territory of Việt Nam in 1802. Furthermore, this was the first time that Vietnamese nationalists in the northern, central and southern regions of the country officially recognized this name. In March, activists in the North always mentioned Đại Việt (Great Việt), the name used before the 15th century by the Lê dynasty and its predecessors, while those in the South used Vietnam, and the central leaders used An Nam (Peaceful South) or Đại Nam (Great South, which was used by the Nguyễn Lords). Kim also renamed the three regions of the country—the northern (former Tonkin or Bắc Kỳ) became Bắc Bộ, the central region (former Annam or Trung Kỳ) became Trung Bộ, and the southern areas (former Cochinchina or Nam Kỳ) became Nam Bộ. Kim did this even though at the time the Japanese had