French and Vietnamese troops clashed in Tonkin, when Commandant Henri Rivière seized the citadel of Hanoi with a small force of marine infantry.

The French Third Republic was the system of government adopted in France from 4 September 1870, when the Second French Empire collapsed during the Franco-Prussian War, until 10 July 1940, after the Fall of France during World War II led to the formation of the Vichy government. The French Third Republic was a parliamentary republic.

The Nguyễn dynasty was the last Vietnamese dynasty, preceded by the Nguyễn lords and ruling unified Vietnam independently from 1802 until 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 as well as Tonkin. 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.

Tonkin, also spelled Tongkin, Tonquin or Tongking, is an exonym referring to the area surrounding the Red River Delta of Northern Vietnam. During the 17th and 18th centuries, this term referred to the domain Đàng Ngoài under Trịnh lords' control, including both the Northern and Thanh-Nghệ regions, north of the Gianh River. From 1884 to early 1945, this term was used for the French protectorate of Tonkin, composed of only the northern region.

Henri Laurent Rivière (1827–1883) was a French naval officer and a writer who is chiefly remembered today for advancing the French conquest of Tonkin in the 1880s. Rivière's seizure of the citadel of Hanoi in April 1882 inaugurated a period of undeclared hostilities between France and Dai Nam that culminated one year later in the Tonkin campaign (1883–1886).