With the outbreak of the Great War, or World War I, in 1914 another generation of Vietnamese resistance leaders had passed from the scene, the last group to enjoy leadership by virtue of its scholarly background. But this generation provided an essential link between traditional Vietnam and the modern political movements that followed in the 1920s.

While seeking to maximize the use of Indochina's natural resources and manpower to fight the First World War, France cracked down on all patriotic mass movements in Vietnam.

The country remained an enthusiastic member of the French Empire, and many Vietnamese fought in World War I (see Vietnamese Expeditionary Force).

French entry into the First World War saw the authorities in Vietnam press-gang thousands of “volunteers” into service in Europe, leading to riots throughout Cochinchina. There are 70,000 Vietnamese troops and 70,000 Vietnamese workers, who were forcibly drafted from the villages, were sent to Europe to fight and serve on the French battlefront. They were conscripts, and thousands lost their lives at Somme and Picardy, near the Belgian coast and many more were sacrificed throughout the bloody front in Middle East. Through contacts with Europeans and their writings, some acquired a taste for current ideas of national autonomy, revolutionary struggle, and the like. Vietnam also contributed 184 million piasters in the form of loans and 336,000 tons of food. These burdens proved all the heavier as agriculture was hard hit by natural disasters from 1914 to 1917.

Lacking a unified nationwide organization, the Vietnamese national movement, though still vigorous, failed to take advantage of the difficulties France was experiencing as a result of war to stage any significant uprisings.

The scholars' movement had declined while new social forces were not yet strong enough to promote large-scale campaigns.

By 1915, all three sectors of Vietnam had daily newspapers written in the Romanized quốc ngữ script. In 1918 the University of Hanoi, founded by Vietnamese, was permitted by the French.

Both Vietnamese victories and losses on World War I battlefields contribute significantly to Vietnam's national identity. At the time it was referred to Vietnam's "Bloody Baptism under Fire." Over 30,000 Viet ancestors died during the conflict and more than 60,000 were wounded when fought on, and gave their lives for, the French side during the First World War. The Vietnamese also endured additional heavy taxes to help pay for France's war efforts.

Numerous anti-colonial revolts occurred in Vietnam during the war, all easily suppressed by the French. In May 1916, the sixteen-year-old king, Duy Tân, escaped from his palace in order to take part in an uprising of Vietnamese troops organized by Thái Phiên and Trần Cao Vân. The French were informed of the plan and the leaders arrested and executed. Duy Tân was deposed and exiled to Réunion Island in the Indian Ocean.

One of the most effective uprisings during this period was in the northern Vietnamese province of Thái Nguyên. Some 300 Vietnamese soldiers revolted and released 200 political prisoners, whom, in addition to several hundred local people, they armed. The rebels held the town of Thái Nguyên for several days, hoping for help from Chinese nationalists. None arrived, however, and the French retook the town and hunted down most of the rebels.

It was also about this time that young Hồ Chí Minh arrived in the United States, where apparently he stayed for a few years. There was no doubt that he did the menial work to support himself, while learning and absorbing the American language and culture. He acquired an affinity with the blacks in New York, Harlem in particular, and when he declared independence for Vietnam on September 2, 1945 in Hanoi, Hồ quoted verbatim the preamble of the American Declaration of Independence.

Following World War I, foreign investment in Vietnam mushroomed. As a result, coal mines in the North, rubber plantations in Central and South Vietnam, and the rapid increase of production for rice farmers in the south spawned a working class, as well as a landlord class, rice exporters in Saigon, and a modern intelligentsia.

An important development in the early part of the twentieth century was the increased use of quốc ngữ in the northern part of the country through a proliferation of new journals printed in that script. There had been quốc ngữ publications in Cochinchina since 1865, but in 1898 a decree of the colonial government prohibited publication without permission, in the protectorate areas, of periodicals in quốc ngữ or chữ nôm that were not published by a French citizen. In 1913 Nguyen Van Vinh succeeded in publishing Đông Dương Tạp Chí (Indochinese Review), a strongly antitraditional but pro-French journal. He also founded a publishing house that translated such Vietnamese classics as the early 19th century poem "Kim Vân Kiều," as well as nôm classics into quốc ngữ. Nguyen Van Vinh's publications, while largely pro-Western, were the major impetus for the increasing popularity of quốc ngữ in Annam and Tonkin. In 1917 the moderate reformist journalist Pham Quynh began publishing in Hanoi the quốc ngữ journal Nam Phong, which 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, and one of their main activities was to punish traitors in the pay of the French.

Connected to these secret societies, a movement led by a former bonze, Phan Xich Long, was organized in 1913. Its members, wearing white clothes and turbans, attacked the cities with primitive weapons. Phan Xich Long was eventually captured and executed by the French. In 1916, underground societies in Cochinchina tried to attack several administrative centers, including the central prison in Saigon and the residence of the local French governor. On the night of February14, 1916, thousands of people armed with knives and wearing amulets infiltrated Saigon and fought French police and troops who succeeded in defeating them.

The colonial administration, while harshly suppressing the national movement, sought to appease the elite by introducing a few paltry reforms, with promises of important postwar reforms from the more generous "liberal" governors. These promises were never fulfilled. The fact that France succeeded in holding on to Vietnam during the war years was mainly due to the weakness of the national movement. There were of' course patriots to carry on the fight for national independence, but the new and still embryonic social forces failed to give the movement the necessary vigor and direction. Not until these forces had further developed over subsequent decades was the national movement able to be revitalized.

In the years immediately following World War I, the scholar- led Vietnamese independence movement in Cochinchina began a temporary decline as a result, in part, of tighter French control and increased activity by the French-educated Vietnamese elite. The decrease of both French investments in and imports to Vietnam during the war had opened opportunities to entrepreneurial Vietnamese, who began to be active in light industries such as rice milling, printing, and textile weaving. The sale of large tracts of land in the Mekong Delta by the colonial government to speculators at cheap prices resulted in the expansion of the Vietnamese landed aristocracy. These factors in combination led to the rise of a wealthy Vietnamese elite in Cochinchina that was pro-French but was frustrated by its own lack of political power and status.