The Battle of Hanoi on 25 April 1882, was the illegal capture by French naval captain Henri Rivière, acting without his superiors' orders. The French handed the city back later.

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).