Treaty of Saigon
By the Treaty of Saigon in 1862, on June 5, the Vietnamese emperor ceded France three provinces of southern Vietnam to form the French colony of Cochinchina; France also secured trade and religious privileges in the rest of Vietnam and a protectorate over Vietnam's foreign relations. Gradually French power spread through exploration, the establishment of protectorates, and outright annexations. Their seizure of Hanoi in 1882 led directly to war with China (1883–1885), and the French victory confirmed French supremacy in the region. France governed Cochinchina as a direct colony, and central and northern Vietnam under the protectorates of Annam and Tonkin, and Cambodia as protectorates in one degree or another. Laos too was soon brought under French "protection".