At the onset of World War I, Vietnam, nominally under the Nguyễn dynasty, was under French protectorate and part of French Indochina. While seeking to maximize the use of Indochina's natural resources and manpower to fight the war, France cracked down all Vietnamese patriotic movements.^[192] The French entry into World War I saw the authorities in Vietnam press-gang thousands of "volunteers" for service in Europe, leading to uprisings in Tonkin and Cochinchina.^[193] Almost 100,000 Vietnamese were conscripts and went to Europe to fight and serve on the French battlefront, or work as laborers.^[194] Several battalions fought and suffered loss of lives at the Somme and Picardy, while others were deployed at Verdun, the Chemin des Dames, and in Champagne.^[195] Vietnamese troops also served in the Balkans and the Middle East. Exposed to new political ideals and returning to a colonial occupation of their own country (by a ruler that many of them had fought and died for), resulted in some sour attitudes. Many of these troops sought out and joined the Vietnamese nationalist movement focused on overthrowing the French.

In 1917 the moderate reformist journalist Phạm Quỳnh had begun publishing the quốc ngữ journal Nam Phong in Hanoi. It addressed the problem of adopting modern Western values without destroying the cultural essence of the Vietnamese nation. By World War I, quốc ngữ had become the vehicle for the dissemination of not only Vietnamese, Hán, and French literary and philosophical classics but also a new body of Vietnamese nationalist literature emphasizing social comment and criticism.

In Cochinchina, patriotic activity manifested itself in the early years of the century by the creation of underground societies. The most important of which was the Thiên Địa Hội (Heaven and Earth Association) whose branches covered many provinces around Saigon. These associations often took the form of political-religious organizations, one of their main activities was to punish traitors in the pay of the French.