The outlook for U.S. ratification was not promising. Though major opinion makers and religious denominations supported the treaty, openly hostile Republicans held a majority in the Senate. One group, called the “irreconcilables,” consisted of western progressive Republicans such as Hiram Johnson of California and Robert La Follette of Wisconsin, who opposed U.S. involvement in European affairs. Another group, led by Senator Henry Cabot Lodge of Massachusetts, worried that Article X — the provision for collective security — would prevent the United States from pursuing an independent foreign policy. Was the nation, Lodge asked, “willing to have the youth of America ordered to war” by an international body? Wilson refused to accept any amendments, especially to placate Lodge, a hated rival. “I shall consent to nothing,” the president told the French ambassador. “The Senate must take its medicine.”

To mobilize support, Wilson embarked on an exhausting speaking tour. His impassioned defense of the League of Nations brought audiences to tears, but the strain proved too much for the president. While visiting Colorado in September 1919, Wilson collapsed. A week later, back in Washington, he suffered a stroke that left one side of his body paralyzed. Wilson still urged Democratic senators to reject all Republican amendments. When the treaty came up for a vote in November 1919, it failed to win the required two-thirds majority. A second attempt, in March 1920, fell seven votes short.

The treaty was dead, and so was Wilson’s leadership. The president never fully recovered from his stroke. During the last eighteen months of his administration, the government drifted as Wilson’s physician, his wife, and various cabinet heads secretly took charge. The United States never ratified the Versailles treaty or joined the League of Nations. In turn, the League was weak. When Wilson died in 1924, his dream of a just and peaceful international order lay in ruins.

The impact of World War I can hardly be overstated. Despite bids for power by Britain and France, Europe’s hold on its colonial empires never recovered. The United States, now a major world power, appeared to turn its back on the world when it rejected the Versailles treaty. But in laying claim to Hawaii and the Philippines, asserting power in Latin America, and intervening in Asia, the United States had entangled itself deeply in global politics. By 1918, the nation had gained too much diplomatic clout — and was too dependent on overseas trade — for isolation to be a realistic long-term option.

On the home front, the effects of World War I were no less dramatic. Wartime jobs and prosperity ushered in an era of exuberant consumerism, while the achievements of women’s voting rights seemed to presage a new progressive era. But as peace returned, it became clear that the war had not advanced reform. Rather than embracing government activism, Americans of the 1920s proved eager to relinquish it.