Between 1615 and 1753, French traders also engaged in trade in Vietnam.[86][87] The first French missionaries arrived in 1658, under the Portuguese Padroado. From its foundation, the Paris Foreign Missions Society under Propaganda Fide actively sent missionaries to Vietnam, entering Cochinchina first in 1664 and Tonkin first in 1666.[88] Spanish Dominicans joined the Tonkin mission in 1676, and Franciscans were in Cochinchina from 1719 to 1834. The Vietnamese authorities began[when?] to feel threatened by continuous Christianisation activities.[89] After several Catholic missionaries were detained, the French Navy intervened in 1843 to free them, as the kingdom was perceived as xenophobic.[90] In a series of conquests from 1859 to 1885, France eroded Vietnam's sovereignty.[91] At the siege of Tourane in 1858, France was aided by Spain (with Filipino, Latin American, and Spanish troops from the Philippines)[92] and perhaps some Tonkinese Catholics.[93] After the 1862 Treaty, and especially after France completely conquered Lower Cochinchina in 1867, the Văn Thân movement of scholar-gentry class arose and committed violence against Catholics across central and northern Vietnam.[94]
Between 1862 and 1867, the southern third of the country became the French colony of Cochinchina.[95] By 1884, the entire country was under French rule, with the central and northern parts of Vietnam separated into the two protectorates of Annam and Tonkin. The three entities were formally integrated into the union of French Indochina in 1887.[96][97] The French administration imposed significant political and cultural changes on Vietnamese society.[98] A Western-style system of modern education introduced new humanist values.[99] Most French settlers in Indochina were concentrated in Cochinchina, particularly in Saigon, and in Hanoi, the colony's capital.[100]
During the colonial period, guerrillas of the royalist Cần Vương movement rebelled against French rule and massacred around a third of Vietnam's Christian population.[101] After a decade of resistance, they were defeated in the 1890s by the Catholics in reprisal for their earlier massacres.[102][103] Another large-scale rebellion, the Thái Nguyên uprising, was also suppressed heavily.[104] The French developed a plantation economy to promote export of tobacco, indigo, tea and coffee.[105] However, they largely ignored the increasing demands for civil rights and self-government. An increasing dissatisfaction, even led to half-hearted, badly co-ordinated, and still worsely executed plots to oust the French, like the infamous Hanoi Poison Plot of 1908.
A nationalist political movement soon emerged, with leaders like Phan Bội Châu, Phan Châu Trinh, Phan Đình Phùng, Emperor Hàm Nghi, and Hồ Chí Minh fighting or calling for independence.[106] This resulted in the 1930 Yên Bái mutiny by the Vietnamese Nationalist Party (VNQDĐ), which the French quashed. The mutiny split the independence movement, as many leading members converted to communism.[107][108][109]
The French maintained full control of their colonies until World War II, when the war in the Pacific led to the Japanese invasion of French Indochina in 1940. Afterwards, the Japanese Empire was allowed to station its troops in Vietnam while the pro-Vichy French colonial administration continued.[110][111] Japan exploited Vietnam's natural resources to support its military campaigns, culminating in a full-scale takeover of the country in March 1945. This led to the Vietnamese Famine of 1945 which killed up to two million people.[112][113]