The First World War began in Europe in 1914, engulfing the United States nearly three years later. This was the war that Americans of a progressive generation had sought to avoid, isolationists by ignoring Europe, internationalists by erecting the machinery that might prevent a small dispute from becoming a larger conflict. At first, internationalists despaired. In 1915, however, the military carnage in Europe energized Americans who argued not that international cooperation was impossible, but that it had not been sufficiently tried. In short, they resolved to work harder, to construct peacekeeping machinery that might work much more effectively than the failed pre-1914 arbitration and conciliation treaties.
Although arbitration and conciliation had been discredited, few internationalists gave up on the quintessentially American faith in law. Led by former president Taft, many Americans joined what soon became the most important internationalist organization of the wartime years, the League to Enforce Peace. Such a league, argued its founders, would incorporate a judicial court to provide the basis for international stability. Formed in the spring of 1915, it aimed to prevent war, not to win a war once war broke out or to use force as a threat to prevent states from violating the peace in the first place. This point is important, because the League to Enforce Peace really had little inclination to enforce anything. Its program reflected the prewar faith in procedural machinery that could be used to resolve differences before they erupted in war. It would compel nations to submit their disputes to various agencies in order to guarantee that peaceful disputes did not turn violent. Sanctions, both economic and military, theoretically existed to compel a state (or states, as long as they were members of the organization) to resolve differences peacefully. Presumably, sanctions would be applied whenever a party to a dispute refused to follow prescribed procedures. But theory and practice were never reconciled, for the League to Enforce Peace recommended no use of force in the event that states rejected its recommendations or decisions. As one of its leaders, Harvard president A. Lawrence Lowell, put it, no international organization could be effective once war erupted; it had to succeed in preventing war, not ending war.
Other internationalists agreed. Few would endorse the potential use of force by any international organization. The World's Court League, second only to the League to Enforce Peace as an internationalist organization with substantial national influence, called for a judicially centered body with no power to compel the submission of controversies or to uphold decisions. No power meant no effectiveness, but the noise of war ironically shrouded this reality in the context of World War I. The emphasis on judicial authority without enforcement provisions spoke to the aspirations of most Americans, who believed that it really made no sense to fight a war to prevent a war. Pacifists, of course, applauded such an approach. So did many lawyers who either neglected the need for enforcement to compel people (or states) to obey the law, or who were so enamored of the logic and sanctity of law that they ignored the fundamentally anarchic nature of the international system.