The American century began, in a sense, 100 years ago today. On April 6, 1917, the House of Representatives voted to declare war on Germany two days after the Senate had done so, and the United States joined the Allied side in World War I. Over the next year and a half, American troops helped turn the tide of the war in bloody battles at places like Chateau-Thierry, Saint-Mihiel and the Meuse-Argonne.
The Great War established the United States as the guarantor of peace in Europe, but it was a role that America, then and later, embraced only reluctantly. Today, with a toxic brand of nationalism again on the march in Europe and the United States looking inward, World War I remains an important reminder of both the indispensability of American power for a peaceful Europe and the challenges that have always attended its use.
The United States sought to stay out of the war in Europe as long as possible despite the warnings of those like former President Theodore Roosevelt that Germany was attempting to dominate Europe, which would upset the balance of power and threaten America’s own security. He wrote:
Do you not believe that if Germany won on this war, smashed the English fleet and destroyed the British Empire, within a year or two she would insist on taking the dominant position in South and Central America?
From there, Germany would have posed a threat to U.S. control of the seas and supremacy in the Western Hemisphere.
In February 1915, the Imperial German Navy announced that it would sink hostile merchant vessels in the waters off Britain and Ireland. That May, a German submarine sank the liner Lusitania, which was steaming from New York to Liverpool, killing 128 Americans. Yet a full year and a half later, in November 1916, Woodrow Wilson won re-election to the presidency in part on a pledge to keep the United States out of the war. Only the resumption of unrestricted submarine warfare and the timely release by British intelligence of an intercepted German telegram offering to return the American Southwest to Mexico in exchange for declaring war finally pulled the United States in.
When America did join the fight, Wilson sold it to the public not in terms of restoring the balance of power but because, as he argued in his message to Congress seeking a declaration of war, “the world must be made safe for democracy.” In his famous “Fourteen Points,” Wilson called for a peace without victory, national self-determination, disarmament, and an end to both secret diplomacy and closed trading blocs. Most notably, he also proposed a new League of Nations to resolve international disputes. Wilson’s call mobilized public support for the war effort but raised unrealistic expectations that would soon fuel disappointment.
World War I and its aftermath proved in many ways disillusioning for the United States. The U.S. military in early 1917 was woefully unprepared for conflict with a European great power, and suffered accordingly. The American Expeditionary Forces suffered more than 53,000 battle deaths (plus over 60,000 non-combat deaths). More Americans were killed in action between April 1917 and the November 1918 armistice than during the entire Vietnam War (to this day, the Meuse-Argonne remains the deadliest battle in American history). The end of the war coincided with, and contributed to, the worst flu pandemic in modern history, which killed hundreds of thousands more.
Meanwhile, the Paris Peace Conference showed that European militarism and the “old diplomacy” that Wilson had railed against were still very much alive. British and French recalcitrance soured many Americans on their recent allies. Despite Wilson’s call for a peace without victory that would avoid leaving Germany embittered, the British and especially the French, on whose territory most of the war had been fought, sought a permanent weakening of Germany — demands to which Wilson acquiesced in part to ensure support for the League of Nations. They succeeded in imposing territorial changes that ran counter to Wilson’s insistence on national self-determination, as well as a large indemnity that many Germans and others would blame for the hyperinflation their country faced in the early 1920s.
At home, Wilson’s League of Nations faced widespread skepticism both in Congress and among the public. Meanwhile, the Bolshevik Revolution in Russia had sparked America’s first “red scare” and paroxysms of anti-immigrant hysteria. Despite a nationwide speaking tour that ruined his health, Wilson failed to persuade Congress to ratify the Treaty of Versailles, and the United States remained outside the new League of Nations.
In the aftermath of the war and the debacle of the Versailles Treaty, Warren Harding was elected president in 1920 calling for “a return to normalcy.” Above all, this meant a reduction of U.S. engagement in Europe. Within a year of the armistice, the U.S. Army had shrunk from almost 4 million men (including officers) to just 220,000. Congress then rejected a proposal to establish a standing army that could be called on to respond to contingencies in Europe. The backlash against immigrants continued as well. The Quota Act of 1921 slashed immigration from Southern and Eastern Europe (immigrants from Asia had been barred since 1917).
Of course, the United States did not really have the luxury of withdrawing. Instability in Europe and the rise of fascism in the 1920s and 1930s created a new threat that America’s wartime allies were too weak and divided to confront on their own. As Theodore Roosevelt had recognized a generation before, a country that dominated Europe — as Hitler’s Germany again sought to do — would sooner or later end up posing a threat to the United States.
It remained, however, a difficult case to make to the American public. Theodore Roosevelt’s cousin Franklin, who became president in 1933, recognized what others did not:
The Nazi masters of Germany have made it clear that they intend not only to dominate all life and thought in their own country, but also to enslave the whole of Europe, and then to use the resources of Europe to dominate the rest of the world.
Yet he worried that the American people would not back him if he tried to take the country into another European war, even after German forces had conquered France and appeared poised to conquer Britain. Until Hitler’s rash decision to declare war on the United States four days after Japanese planes bombed Pearl Harbor in December 1941, the best FDR could do was to support the Allied cause indirectly, through programs like Lend Lease, which allowed the United States to provide aid (including war materiel) to the Allied powers. We all know what happened next.
Unlike the situation in 1919, the United States did not disengage from Europe after World War II — thanks in no small part to the emergence of a new threat to European security in the form of the Soviet Union. In response, the United States created the institutions of a new liberal order that helped lock in American participation in global — particularly European — affairs. Among these was NATO, whose goal, its first secretary general stated, was “to keep the Americans in, the Russians out, and the Germans down.” Beyond these institutions, the ideological threat posed by Soviet Communism and the fear of the Soviet military ensured public support for deep U.S. engagement in Europe. For the next 70 years, Atlanticism was the object of bipartisan consensus in the United States, even as the Soviet danger and memories of two world wars curbed Europeans’ worst political instincts.
Today, though, memories of that history are fading on both sides of the Atlantic. Facing new challenges at home, the U.S. public and the new administration appear less committed to underwriting European security, as indicated by the Donald Trump’s view of NATO as a service provided by the United States for which the Europeans should pay. Meanwhile, the specters of nationalism and authoritarianism are again stalking Europe. Russia has reverted to the role of spoiler, seeking through a mixture of disinformation, illicit financial flows and intimidation to fracture European unity and drive a wedge between Europe and the United States. Most Americans continue to support U.S. global leadership, but support is lowest among young adults with no memory of Europe’s dark history. Trump’s ambivalence about NATO and the European Union, meanwhile, is causing questions about both friends and foes about U.S. commitments.
In many ways, European geopolitics is reverting to its pre-1945 form, with a weak and divided Europe facing an aggressively revisionist power in Russia. That prospect is worrying for a host of reasons. If European states lose faith in U.S. security guarantees, they will take matters into their own hands, recreating earlier security dilemmas. German rearmament (particularly its development of nuclear weapons) would be only marginally more comforting to some other states — in this case Russia — than it was in the early 1930s. Questions about U.S. commitments could also spark Russian efforts to test them, creating a recipe for miscalculation analogous to the crisis of July 1914. And while Vladimir Putin may not be seeking hegemony in Europe the way Wilhelm II, Hitler or Stalin did, Russia’s ambitions are incompatible with the idea of a Europe whole, free, and at peace, and with U.S. security interests, and they can only be checked by a strong U.S. commitment to maintaining European security.
Reluctance to bear the costs of Europe’s security are one indicator that the curtain may be coming down on the American century. They are also in keeping with attitudes both before the U.S. entered World War I, and after the November 1918 armistice. Yet the past 100 years have vindicated the worries of both Roosevelts: Europe’s insecurity is a danger to the United States, and in times of crisis only the United States can save Europe from its demons.
Jeffrey Mankoff is a senior fellow at the Center for Strategic and International Studies and a Truman National Security Fellow. He is the author of Russian Foreign Policy: The Return of Great Power Politics.