Empire of Vietnam in the context of "August Revolution"

The Nguyễn dynasty (Vietnamese: Nhà Nguyễn or Triều Nguyễn, chữ Nôm: 茹阮, chữ Hán: 朝阮) was the last Vietnamese dynasty, preceded by the Nguyễn lords and ruling unified Vietnam independently from 1802 until the start of the French protectorate in 1883. Its emperors were members of the House of Nguyễn Phúc. During its existence, the Nguyễn empire expanded into modern-day Southern Vietnam, Cambodia, and Laos through a continuation of the centuries-long Nam tiến and Siamese–Vietnamese wars. With the French conquest of Vietnam, the Nguyễn dynasty was forced to give up sovereignty over parts of Southern Vietnam to France in 1862 and 1874, and after 1883 the Nguyễn dynasty only nominally ruled the French protectorates of Annam (Central Vietnam) as well as Tonkin (Northern Vietnam). Backed by Imperial Japan, in 1945 the last Nguyễn emperor Bảo Đại abolished the protectorate treaty with France and proclaimed the Empire of Vietnam for a short time until 25 August 1945.

The House of Nguyễn Phúc established control over large amounts of territory in Southern Vietnam as the Nguyễn lords (1558–1777, 1780–1802) by the 16th century before defeating the Tây Sơn dynasty and establishing their own imperial rule in the 19th century. The dynastic rule began with Gia Long ascending the throne in 1802, after ending the previous Tây Sơn dynasty. The Nguyễn dynasty was gradually absorbed by France over the course of several decades in the latter half of the 19th century, beginning with the Cochinchina Campaign in 1858 which led to the occupation of the southern area of Vietnam. A series of unequal treaties followed; the occupied territory became the French colony of Cochinchina in the 1862 Treaty of Saigon, and the 1863 Treaty of Huế gave France access to Vietnamese ports and increased control of its foreign affairs. Finally, the 1883 and 1884 Treaties of Huế divided the remaining Vietnamese territory into the protectorates of Annam and Tonkin under nominal Nguyễn Phúc rule. In 1887, Cochinchina, Annam, Tonkin, and the French Protectorate of Cambodia were grouped together to form French Indochina.

Tonkin (chữ Hán: 東京), or Bắc Kỳ (北圻), was a French protectorate encompassing modern Northern Vietnam from 1883 to 1949. Like the French protectorate of Annam, Tonkin was still nominally ruled by the Vietnamese Nguyễn dynasty. In 1886, the French separated Tonkin from the Nguyễn imperial court in Huế by establishing the office of "Viceroy" (經略衙, Kinh lược nha). However, on 26 July 1897, the position of Viceroy was abolished, officially making the French resident-superior of Tonkin both the representative of the French colonial administration and the Nguyễn dynasty court in Huế, giving him the power to appoint local mandarins. In 1887, Tonkin became a part of the Union of Indochina.

In March 1945, the emperor Bảo Đại rescinded the Patenôtre Treaty, ending the French protectorates over Annam and Tonkin, establishing the Empire of Vietnam, a Japanese-backed state. Following the surrender of Japan, ending World War II, the Việt Minh launched the August Revolution which led to the abdication of Bảo Đại and the declaration of independence of the Democratic Republic of Vietnam.

Bảo Đại (Vietnamese: [ɓa᷉ːw ɗâːjˀ], chữ Hán: 保大, lit. "keeper of greatness", 22 October 1913 – 31 July 1997), born Nguyễn Phúc (Phước) Vĩnh Thụy (chữ Hán: 阮福永瑞), was the 13th and final emperor of the Nguyễn dynasty, the last ruling dynasty of Vietnam. From 1926 to 1945, he was de jure emperor of Annam and Tonkin, which were then protectorates in French Indochina, covering the present-day central and northern Vietnam. Bảo Đại ascended the throne in 1932.

The Japanese ousted the Vichy French administration in March 1945 and ruled through Bảo Đại, who proclaimed the Empire of Vietnam. He abdicated in August 1945 after Japan surrendered.

The declaration of independence of the Democratic Republic of Vietnam (Vietnamese: Tuyên ngôn độc lập Việt Nam Dân chủ Cộng hòa) was written by Hồ Chí Minh, and announced in public at the Ba Đình square in Hanoi on 2 September 1945. It led to the foundation of the Democratic Republic of Vietnam (DRV), replacing the Empire of Vietnam under the Nguyễn dynasty and Emperor Bảo Đại, who abdicated on August 25.

This declaration was a declaration of independence from France, but France had initially never recognized the DRV. France formed the independent and unified State of Vietnam within the French Union when the Élysée Accords took effect on 14 June 1949, as an alternative method to solve the Vietnam question. This associated state would become the Republic of Vietnam. The declaration is also considered the foundation of the Socialist Republic of Vietnam although this state was actually formed on 2 July 1976.

Southern Vietnam (Vietnamese: Nam Bộ) is one of the three geographical regions of Vietnam, the other two being Northern and Central Vietnam. It includes 2 administrative subregions, which in turn are divided into 19 First Tier units, of which 17 are provinces and 2 are municipalities.

Known as Nam Bộ today in Vietnamese, it was historically called Gia Định (1779–1832), Nam Kỳ (1832–1945, during Nguyễn's Lục tỉnh and French Cochinchina), Nam Bộ (1945 to the present, encompassing the Empire of Vietnam and the Democratic Republic of Vietnam), and Nam Phần, sometimes Nam Việt (1948–1975, during the State of Vietnam and the Republic of Vietnam). Cochinchina is a historical exonym for this region during the colonial period, which referred to the entire domain of Đàng Trong in the feudal period. A more accurate term for the southern region is Lower Cochinchina, or Basse-Cochinchine in French.

During the aftermath of World War II and the Cold War, the Indochina wars (Vietnamese: Chiến tranh Đông Dương) were a series of wars which were waged in Indochina from 1945 to 1991, by communist forces (mainly ones led by Vietnamese communists) against the opponents (mainly the Vietnamese nationalists, Trotskyists, the State of Vietnam, the Republic of Vietnam, the French, American, Laotian royalist, Cambodian and Chinese communist forces). The term "Indochina" referred to former French Indochina, which included the current states of Vietnam, Laos, and Cambodia. In current usage, it applies largely to a geographic region, rather than to a political area. The wars included:

• The First Indochina War (called the Indochina War in France and the French War in Vietnam) began after the end of World War II with the War in southern Vietnam (1945–1946), which acted as the precursor to the First Indochina War. The conflict officially began in 1946 and lasted until the French defeat in 1954. After a long campaign of unsuccessful resistance against the French and the Japanese, Viet Minh forces claimed a victory in the August Revolution after Japanese forces surrendered to the Allies on 15 August 1945, leading to the fall of the Empire of Vietnam and Nguyễn dynasty. In the War in southern Vietnam (1945–1946), British forces temporarily occupied the South with the objective of disarming Japanese forces, starting from 13 September 1945, only to restore French colonial control in 1946. Meanwhile, the communist Viet Minh sought to consolidate power by terrorizing and purging rival Vietnamese nationalist groups and Trotskyist activists. In the United Nations, and through their alliance with the United Kingdom and the United States, the French demanded return of their former Indochina colony prior to agreeing to participate in the NATO alliance (founded in 1949) opposing Soviet expansion beyond the countries of the Warsaw Pact (founded in 1955) in the Cold War. With support from China and the Soviet Union, the communist Viet Minh continued fighting the French Union, including the anti-communist State of Vietnam, ultimately forcing the NATO-backed French out of North Vietnam as a result of 1954 Geneva Conference.
• The Second Indochina War (called the Vietnam War in the United States and the Anti-American War by North Vietnam) began as a conflict between the United States-backed South Vietnamese government and its opponents, both the North Vietnamese-based communist Viet Cong (National Liberation Front) and the People's Army of Vietnam (PAVN), known in the West as the North Vietnamese Army (NVA). The conflict began in 1955 and lasted until 1975 when the North Vietnamese army conquered South Vietnam. The United States, which had supported France and its native vassal during the First Indochina war, backed the Republic of Vietnam government in opposition to the communist Viet Cong and PAVN. The North benefited from military and financial support from China and the Soviet Union, members of the communist bloc, Fighting also occurred during this time in Cambodia between the US-backed government, the PAVN, and the communist-backed Khmer Rouge, which also fought alongside deposed King Sihanouk's government in exile (known as the Cambodian Civil War, 1967–1975) and in Laos between the US-backed government, the PAVN, and the communist-backed Pathet Lao (known as the Laotian Civil War or Secret War, 1959–1975).
• The Third Indochina War was a period of prolonged conflict following the Second Indochina War. The conflict began in 1978 and lasted until the 1991 Paris Peace Agreements on 23 October 1991, in which several wars were fought:

The abdication of Bảo Đại (Vietnamese: Chiếu thoái vị của Hoàng Đế Bảo Đại) took place on 25 August 1945 and marked the end of the 143-year reign of the Nguyễn dynasty over Vietnam ending the Vietnamese monarchy. The fall of the Nguyễn dynasty also led to the fall of its Empire of Vietnam, de facto controlled by Japan. Emperor Bảo Đại abdicated in response to the August Revolution. A ceremony was held handing power over to the newly established Democratic Republic of Vietnam, which was established during the end of World War II in Asia as Vietnam had been occupied by French and later Japanese imperialists.

After the Việt Minh sent a telegram to the Imperial City of Huế demanding the abdication of Emperor Bảo Đại, he announced that he would abdicate and officially abdicated on 25 August. After a representative of the Việt Minh convinced Bảo Đại to hold a public abdication ceremony, he did so on 30 August 1945. The passing of the ceremonial seal and sword had been seen as symbolically "passing the Mandate of Heaven over to the government of the Democratic Republic of Vietnam". Following his abdication Emperor Bảo Đại became "citizen Vĩnh Thụy" (公民永瑞, công dân Vĩnh Thụy) and would become an advisor to the new Democratic Republic of Vietnam government in Hanoi.