Backed by Imperial Japan, in 1945 the last Nguyễn emperor Bảo Đại abolished protectorate treaty with France and proclaimed the Empire of Vietnam for a short time until 25 August 1945.

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.

In the second year of his rule, he asked the Jiaqing Emperor of the Qing dynasty to confer on him the title 'King of Nam Việt / Nanyue' (南越 in Chinese character) after seizing power in Annam.

[24] The Nguyễn clan, which originated in the Thanh Hóa Province had long exerted substantial political influence and military power throughout early modern Vietnamese history through one form or another.

Nguyễn Kim, who had served as leader of the loyalists throughout the 12 years of the Lê–Mạc War (from 1533 to 1545) and throughout the Northern and Southern dynasties period, was assassinated in 1545 by a captured Mạc general, Dương Chấp Nhất.

[30][31][32] The 17th-century war between the Trịnh and the Nguyễn ended in an uneasy peace, with the two sides creating de facto separate states although both professed loyalty to the same Lê dynasty.

The Tây Sơn received widespread popular support as they presented themselves as champions of the Vietnamese people, who rejected any foreign influence and fought for the full reinstitution of the Lê dynasty.

In 1775, the 13-year-old Nguyễn Ánh escaped and with the help of the Vietnamese Catholic priest Paul Hồ Văn Nghị soon arrived at the Paris Foreign Missions Society in Hà Tiên.

The French purchased and supplied equipment and weaponry, reinforcing the defense of Gia Định, Vĩnh Long, Châu Đốc, Hà Tiên, Biên Hòa, Bà Rịa and training Ánh's artillery and infantry according to the European model.

Nguyễn Hữu Chỉnh wanted to unify the country under Lê rule, and began to prepare the army to march south and attack the Tây Sơn.

[54] In 1788 de Behaine and Ánh's son, Prince Cảnh, arrived in Gia Định with modern war equipment and more than twenty Frenchmen who wanted to join the army.

[62][63] The Nguyen dynasty was founded as a tributary state of the Qing Empire, with Gia Long receiving an imperial pardon and recognition as the ruler of Vietnam from the Jiaqing Emperor for recognizing Chinese suzerainty.

[70] In 1808, a British fleet led by William O'Bryen Drury mounted an attack on the Red River Delta, but was soon driven back by the Vietnamese navy and suffered several losses.

[74][75][69] In 1811, a coup d'état broke out in the Kingdom of Cambodia, a Vietnamese tributary state, forcing the pro-Vietnamese King Ang Chan II to seek support from Vietnam.

[90] A second revolt began the following year, led by a Muslim clergy named Ja Thak with support from the old Cham royalty, highland people, and Vietnamese dissents.

[92] The rebellion lasted for two years, gathering much support from Vietnamese Catholics, Khmers, Chinese merchants in Saigon, and even the Siamese ruler Rama III until it was crushed by the government forces in 1835.

[78] Minh Mạng also expanded his empire westward, putting central and southern Laos under Cam Lộ Province, and collided with his father's former ally – Siam, in Vientiane and Cambodia.

In 1845, the American warship USS Constitution landed in Đà Nẵng, taking all local officials hostage with the demands that Thiệu Trị free imprisoned French bishop Dominique Lefèbvre.

[113] Tự Đức, or Prince Hồng Nhậm was Thiệu Trị's youngest son, well-educated in Confucian learning, he was crowned by minister and co-regent Trương Đăng Quế.

[112] In the 1850–70s, a new class of liberal intellectuals emerged in the court as persecution relaxed, many of them Catholics who had studied abroad in Europe, most notably Nguyễn Trường Tộ, who urged the emperor to reform and transform the Empire following the Western model and open Vietnam to the west.

[124][125] In June 1862, the Treaty of Saigon was signed, resulting in Vietnam losing three southern provinces; Gia Định, Mỹ Tho, Biên Hòa which became the basis of French Cochinchina.

Tự Đức immediately sent delegations to negotiate with Garnier, but Prince Hoàng Kế Viêm, governor of Sơn Tây, had enlisted the Chinese Black Flags militia of Liu Yongfu to attack the French.

In September 1882, 17 Chinese divisions (200,000 men) crossed the Sino-Vietnamese borders and occupied Lạng Sơn, Cao Bằng, Bac Ninh, and Thái Nguyên, under the pretext of defending against the French aggression.

Tôn Thất Thuyết excoriated Phan Đình Phùng and sent him from the court to his home territory, where later he led a nationalist resistance movement against the French for ten years.

In November, Emperor Hiệp Hòa and Trần Tiễn Thành were executed by Nguyễn Văn Tường and Tôn Thất Thuyết for their perceived pro-French sympathies.

[60] The leader of the pro-war faction, Tôn Thất Thuyết and his supporters revolted against the French in July 1885, but were forced to retreat to the Laotian highlands with the young emperor Hàm Nghi (Nguyễn Phúc Ưng Lịch.)

[171] From this period onwards any imperial edicts issued by the Emperors of Đại Nam had to be confirmed by the Resident-Superior of Annam giving him both legislative and executive power over the Nguyễn government.

[178] Frequently, there were twelve governor-generals and eleven governors, although, in some periods, the Emperor would appoint a "commissioner in charge of patrolled borderlands" (kinh lược sứ) that supervising entire northern of the southern part of the kingdom.

[221] Emperors Minh Mạng, Thiệu Trị and Tự Đức, were opposed to French involvement in Vietnam, and tried to reduce the country's growing Catholic community.

[239] The Mường people inhabited the hills west of the Red River Delta, and although subordinate to the central authority, they were permitted to bear arms, a privilege not accorded to any other subjects of the court of Huế.