I.

When US president Woodrow Wilson asked Congress for a declaration of war against Germany in April 1917, he argued that unrestricted submarine attacks on American ships meant the United States was already effectively involved in the conflict. Germany was “engaged in warfare against citizens of the United States on the seas,” he said, and America would enter the war “only where we are clearly forced into it because there are no other means of defending our rights.”

Wilson presented American involvement in World War I as a reluctant necessity, but he also saw the war as the catalyst for an ambitious political project. “German submarine warfare against commerce,” he said, “is a warfare against mankind. It is a war against all nations.” He observed that international law “had its origin in the attempt to set up some law which would be respected and observed upon the seas, where no nation had right of dominion and where lay the free highways of the world.” He called upon “free and self-governed peoples of the world” to set up a “steadfast concert for peace.” This “partnership of democratic nations … shall bring peace and safety to all nations.” While Wilson frequently reiterated this universal message, he also outlined a more specific goal: “The world must be made safe for democracy.”

John Ikenberry is a professor of politics and international affairs at Princeton University, and in 2020 he published a book about the history and mechanics of liberal internationalism called A World Safe for Democracy. Wilson plays a prominent role in this history as the founder of the ill-fated League of Nations, which emerged from the carnage of World War I. While Ikenberry credits the League of Nations with influencing the development of future liberal internationalist institutions, he focuses on why the League failed. The primary problem—apart from Wilson’s failure to convince Congress to join the organisation—was the League’s reliance on “public opinion and moral suasion” as the “means to activate cooperation and collective security.” Wilson believed the League of Nations would function as the “organizing moral force of men throughout the world,” which would prevent crimes like aggression by exposing and condemning them.

“The Wilsonian version of liberal internationalism was built around a thin set of institutional commitments,” Ikenberry writes. Wilson assumed that nations would cooperate without clear political, economic, and security incentives to do so. One reason these incentives didn’t exist was the lack of state power and coordination to establish and enforce them. Unlike post-World War II liberal-internationalist institutions like NATO and the UN, the League of Nations didn’t include the United States. Ikenberry explains that other major members were dissatisfied with the League and the broader system in which it operated: “The international order that emerged after 1919 had few champions. The United States failed to join the League of Nations, France did not get the security guarantees it sought, and Germany was left seething with grievances.” While the League of Nations generally lacked the institutional strength to compel members to modify their behaviour in significant ways, the Treaty of Versailles had the opposite problem: it imposed such onerous penalties and restrictions on Germany that it created the conditions for the rise of the Nazis. And it turned out to be unenforceable as well.

After the Japanese invasion of Manchuria in 1931 and the Italian invasion of Abyssinia (now Ethiopia) in 1935, it was clear that the League of Nations was incapable of restraining the actions of its own members and maintaining global security. Japanese generals and Benito Mussolini were undeterred by public opinion and unmoved by moral suasion. Hitler didn’t mind international censure, either. The League could do nothing to stop German rearmament in the mid-1930s, and the failure of Wilsonian internationalism was complete by the time the Nazis annexed Austria in 1938. World War II would officially begin a year and a half later with the German invasion of Poland. Both countries were members of the League.

In one sense, the League of Nations was a victim of historical circumstance. It was created at a time when the international system was undergoing major shifts—from the collapse of four empires to the shattering of the great-power balance in Europe—and within a decade, the world sank into the Great Depression. These factors fuelled the rise of new totalitarian movements like communism and fascism. While the United States emerged as a more powerful force in the world, Washington shifted toward neutrality and isolationism in the aftermath of World War I. All of these developments made World War II more likely, and ensured that democratic countries would be unprepared once it arrived. The outbreak of war in 1939 was the nadir for liberal internationalism, but within a few years the victorious democratic powers would build the foundation of a postwar global order that has survived to this day.

II.

The effort to build a functioning international community is one of the most ambitious political projects ever undertaken, so it isn’t surprising that this effort has suffered many setbacks. However, liberal internationalism has proven to be a remarkably resilient idea over the centuries.