United States

Chances for peace were blasted by a decision of the German leaders, made at an imperial conference on January 9, 1917, to inaugurate an all-out submarine war against all commerce, neutral as well as belligerent. The Germans knew that such a campaign would bring the United States into the war, but they were confident that their augmented submarine fleet could starve Britain into submission before the United States could mobilize and participate effectively.

The announcement of the new submarine blockade in January left the president no alternative but to break diplomatic relations with Germany, which he did on February 3. At the same time, and in subsequent addresses, the president made it clear that he would accept unrestricted submarine warfare against belligerent merchantmen and would act only if American ships were sunk. In early March he put arms on American ships in the hope that this would deter submarine attacks. The Germans began to sink American ships indiscriminately in mid-March, and on April 2 Wilson asked Congress to recognize that a state of war existed between the United States and the German Empire. Congress approved the war resolution quickly, and Wilson signed it on April 6. (For U.S. military involvement in World War I, see the article World War I.)

Mobilization

Generally speaking, the efforts at mobilization went through two stages. During the first, lasting roughly from April to December 1917, the administration relied mainly on voluntary and cooperative efforts. During the second stage, after December 1917, the government moved rapidly to establish complete control over every important phase of economic life. Railroads were nationalized; a war industries board established ironclad controls over industry; food and fuel were strictly rationed; an emergency-fleet corporation began construction of a vast merchant fleet; and a war labour board used coercive measures to prevent strikes. Opposition to the war was sternly suppressed under the Espionage Act of 1917. At the same time, the Committee on Public Information, headed by the progressive journalist George Creel, mobilized publicists, scholars, and others in a vast prowar propaganda effort. By the spring of 1918, the American people and their economy had been harnessed for total war (a near miracle, considering the lack of preparedness only a year before).

ration cardSugar ration card used during World War I, 1917. Encyclopædia Britannica, Inc.

America’s role in the war

The American military contribution, while small compared to that of the Allies during the entire war, was in two respects decisive in the outcome. The U.S. Navy, fully prepared at the outset, provided the ships that helped the British overcome the submarine threat by the autumn of 1917. The U.S. Army, some 4,000,000 men strong, was raised mainly by conscription under the Selective Service Act of 1917; the American Expeditionary Force of more than 1,200,000 men under General Pershing reached France by September 1918, and this huge infusion of manpower tipped the balance on the Western Front and helped to end the war in November 1918, a year earlier than military planners had anticipated.

World War I: “Wake Up” paradeMarchers in a “Wake Up” parade, 1917, during World War I.Library of Congress, Washington, D.C.

Wilson’s vision of a new world order

Wilson, WoodrowWoodrow Wilson.Encyclopædia Britannica, Inc.

In one of the most ambitious rhetorical efforts in modern history, President Wilson attempted to rally the people of the world in a movement for a peace settlement that would remove the causes of future wars and establish machinery to maintain peace. In an address to the Senate on January 22, 1917, he called for a “peace without victory” to be enforced by a league of nations that the United States would join and strongly support. He reiterated this program in his war message, adding that the United States wanted above all else to “make the world safe for democracy.” And when he failed to persuade the British and French leaders to join him in issuing a common statement of war aims, he went to Congress on January 8, 1918, to make, in his Fourteen Points address, his definitive avowal to the American people and the world.