In 1881, China declares sovereignty over Annam or Vietnam, sending troops down the Red River to occupy its northern region, Tonkin.

France, angered by continuing Vietnamese persecution of Christian missionaries, renews its colonial expansionism in Indochina (Vietnam, Laos, and Cambodia), which China opposes.

French captain Henri Laurent Riviere (1827-83) is sent with a small force to Tonkin's administrative center, Hanoi, to evict the Chinese and to subdue the rebel "Black Flag Pirates."

He captures the Hanoi fortress, Nam Dinh's coast, and the Hon Gay coal mine.

During a Vietnamese counterattack, Riviere is killed.

French reinforcements are sent to the area, and France obtains a Vietnamese agreement on a treaty ceding Tonkin (1882).

When China renounces the agreement, the French seize Haiphong and Hanoi and bombard the Vietnamese capital of Hue (1883).

During the fighting, both sides negotiate and finally sign a treaty (August 25, 1883) that recognizes French protectorates over northern Vietnam (Tonkin) and central Vietnam (Annam); southern Vietnam (Cochin China) is already under French control.

Ten years later, Siam will relinquish to the French its claims to Laos, which is incorporated into a federation known as French Indochina.