German submarine warfare
There was no possibility of conflict between Germany and the United States so long as the former confined its warfare to the continent of Europe; a new situation full of potential danger arose, however, when the German authorities decided to use their new weapon, the submarine, to challenge British control of the seas. The German admiralty announced in February 1915 that all Allied vessels would be torpedoed without warning in a broad area and that even neutral vessels were not safe. Wilson replied at once that he would hold Germany to “strict accountability” (a conventional diplomatic term) if submarines destroyed American ships and lives without warning. The Germans soon gave broad guarantees concerning American ships, and their safety against illegal submarine attacks was not an issue between the two countries before 1917.
An issue much more fraught with danger was the safety of Americans traveling and working on Allied ships. A German submarine sank the unarmed British liner Lusitania" class="md-crosslink">Lusitania without warning on May 7, 1915, killing, among others, 128 Americans. Wilson at first appealed to the Germans on broad grounds of humanity to abandon submarine warfare, but in the subsequent negotiations he narrowed the issue to one of safety for unarmed passenger liners against violent underseas attack. Momentary resolution came when a submarine sank the unarmed British liner Arabic in August. Wilson warned that he would break diplomatic relations if such attacks continued, and the Germans grudgingly promised not to attack unarmed passenger ships without warning. The controversy escalated to a more dangerous level when a submarine torpedoed the packet steamer Sussex in the English Channel with heavy loss of life in March 1916. In an ultimatum to Berlin, Wilson threatened to break diplomatic relations if the Germans did not cease attacking liners and merchantmen without warning; once again the Germans capitulated, but they threatened to resume unrestricted submarine warfare if the United States failed to force the British to observe international law in their blockade practices.
The New York Herald reporting the sinking of the Lusitania, a British ocean liner, by a German submarine on May 7, 1915.Hulton Archive/Getty Images
The Allies complicated the submarine controversy in late 1915 by arming many of their liners and merchantmen sailing to American ports. Wilson tried to arrange a compromise by which the Allies would disarm their ships in return for a German promise not to sink them without warning. When the British rejected the proposal, the president gave the impression that he would hold Germany accountable for American lives lost on armed ships, setting off a rebellion in Congress and the near passage of resolutions forbidding American citizens to travel on armed ships. Actually, the president had no intention of permitting armed ships to become a serious issue; their status was never a subject of serious controversy between the United States and Germany.
Arming for war
Meanwhile, the increasingly perilous state of relations with Germany had prompted Wilson, in December 1915, to call for a considerable expansion in the country’s armed forces. A violent controversy over preparedness ensued, both in Congress and in the country at large. The army legislation of 1916 was a compromise, with Wilson obtaining only a modest increase in the army and a strengthening of the National Guard, but the Naval Appropriations Act of 1916 provided for more ships than the administration had requested.
The United States enters the Great War
Wilson’s most passionate desire, aside from avoiding belligerency, was to bring an end to the war through his personal mediation. He sent Colonel House to Europe in early 1915 to explore the possibilities of peace and again early in 1916 to press for a plan of Anglo-American cooperation for peace. The British refused to cooperate, and the president, more than ever eager to avoid a final confrontation with Germany on the submarine issue, decided to press forward with independent mediation. He was by this time also angered by the intensification of British blockade practices and convinced that both sides were fighting for world domination and spoils. On December 18, 1916, Wilson asked the belligerents to state the terms upon which they would be willing to make peace. Soon afterward, in secret, high-level negotiations, he appealed to Britain and Germany to hold an early peace conference under his leadership.
Break with Germany
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.