Figure 1. While still fighting in WWI, President Wilson sent American troops to Siberia during the Russian Civil War for both diplomatic and military reasons.

World War I decimated millions and profoundly altered the course of world history. The Great War was America’s first foray into global events. After decades of keeping (mostly) to the Americas and Asia, with little to no activity in Europe, the U.S. showed that it was willing and able to interject itself in European affairs through both foreign policy and military intervention. World War I opened the door for European allies and rivals to expect American involvement in all international theaters, not just in their own hemisphere.

On an international scale, World War I shifted the focus of nations to self-defense, industrialization, and modernization. New technologies and ideas, introduced during The Great War, changed the landscape of armed conflict as well as international relations, enabling industrial-scale warfare as well as new peace-keeping strategies. Catastrophic wartime losses led to a more hopeful model of binding international diplomacy.

At home, World War I had a deep and lasting impact on American society. During the war, there was a spirit of cooperation, support for democratic ideals, and an imperative to rally behind the troops. After the war, however, the social shifts proved to be too great. German aggression and the rise of Communism in Russia prompted mass xenophobia, while segregation and Jim Crow kept Black Americans from exercising the very freedoms they had fought for. American women, who had been fighting for decades for civil rights, found themselves with a stronger voice, having participated heavily in the wartime economy and having contributed to keeping the nation afloat through their volunteer efforts. Violent clashes over racial and economic tensions were evidence of how the war had shifted social roles and ideals. The relationship between Americans and their government also shifted. The U.S. had shown that it was willing to restrict individual freedoms in order to attain foreign policy goals, which set a new precedent for how Americans understood and exercised their constitutional rights. The use of propaganda and the passage of anti-sedition legislation created an undercurrent of paranoia and mistrust that was often focused on immigrants during the post-war Red Scare.

The peace process at Versailles led to a new international landscape where self-determination and national independence existed alongside the last vestiges of colonialism and imperial power. Germany was stripped of economic, industrial, and military resources, leaving a weak and scattered republic that would prove vulnerable to the machinations of Nazism. Meanwhile, nations that still suffered under autocratic rule looked to the Russian Revolution for a blueprint illustrating how to implement a more egalitarian popular rule.

President Woodrow Wilson’s hope for regulating this new geopolitical order, and for preventing another mass slaughter, was invested in the League of Nations and the collective security it might bring. While Wilson’s vision did eventually give rise to more successful international organizations, Congress rejected the president’s ratification efforts for the League. However, many of his Fourteen Points would become the basis for later versions of international law and foreign policy.