Formation of French Indochina
Also called: Indochinese Union, French Indochina
Having taken Vietnam and Cambodia step by step, France joined them into the Indochinese Union; Laos was added later.
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Using the persecution of missionaries as a pretext, France attacked Da Nang in 1858 and by the Treaty of Saigon of 1862 gained eastern Cochinchina (southern Vietnam). It made Cambodia a protectorate in 1863, and by the Treaties of Huế of 1883–1884 turned Annam (central) and Tonkin (northern Vietnam) into protectorates as well. After the Sino-French War (1884–1885) Qing China gave up its claim to suzerainty over Vietnam.
On 17 October 1887 France combined the colony of Cochinchina with the protectorates of Annam, Tonkin and Cambodia into the Indochinese Union under a governor-general, adding Laos, taken from Siam in 1893 (incorporated in 1899). Siam (Thailand), caught between British Burma and French Indochina, kept its independence as a buffer state.