The United States Enters the War

Since the beginning of World War I in 1914, the United States, under President Woodrow Wilson, had maintained strict neutrality, other than providing material assistance to the Allies. Even in May 1915, when a German submarine sank the British ocean liner Lusitania, killing 128 U.S. citizens out of a total 1,200 dead, the United States, though in uproar, remained neutral


  • October 21, 1916: French renew attack on Verdun
  • November 7: Wilson reelected on antiwar platform; begins diplomatic initiatives
  • February 1, 1917: Germany begins unrestricted submarine warfare
  • February 3: German U-boat sinks U.S. cargo ship Housatonic, United States breaks off diplomatic relations with Germany
  • February 24: United States learns of Zimmermann telegram
  • March 1: Zimmermann telegram published in American press
  • April 2: Wilson asks Congress to declare war
  • April 6: United States declares war on Germany
  • May 24: First U.S. convoy to protect shipping to Europe departs
  • July 4: U.S. troops march through central Paris to Lafayette’s tomb
  • September 4: First U.S. war fatalities
  • November 2–3: First U.S. combat mission
  • January 8, 1918: Wilson gives “Fourteen Points” speech before U.S. Congress

American Neutrality

Since the beginning of World War I in 1914, the United States, under President Woodrow Wilson, had maintained strict neutrality, other than providing material assistance to the Allies. Even in May 1915, when a German submarine sank the British ocean liner Lusitania, killing 128 U.S. citizens out of a total 1,200 dead, the United States, though in uproar, remained neutral. In the autumn of 1916, Wilson was reelected after running largely on a platform of antiwar, pro-neutrality rhetoric.

American Diplomacy

By the time of Wilson’s reelection victory, the war had left millions dead, cities and economies in ruins, and no decisive victory in sight for any side. It seemed that the war might actually burn itself out. In November and December 1916, Wilson began a series of initiatives to broker a resolution, sending out diplomatic notes to the governments of every nation involved. Germany responded positively and went so far as to recommend opening immediate peace negotiations. France, however, responded by launching a renewed attack against the Germans in Verdun. British prime minister David Lloyd George rejected Wilson’s initiative directly.

Unrestricted Submarine Warfare

In January 1917, Germany announced that it would lift all restrictions on Submarine Warfare starting on February 1. This declaration meant that German U-boat commanders were suddenly authorized to sink all ships that they believed to be providing aid of any sort to the Allies. Because the primary goal was to starve Britain into surrendering, the German effort would focus largely on ships crossing the Atlantic from the United States and Canada.

The Housatonic

The first victim of this new policy was the American cargo ship Housatonic, which a German U-boat sank on February 3, 1917. In response, President Wilson broke off diplomatic relations with Germany the same day. The escalation was serious and turned out to be a major step toward the United States’ entry into the war.

The Zimmermann Telegram

In the meantime, other German mischief paved the road to war with the United States even more smoothly. In February 1917, British intelligence intercepted a telegram from Germany that they had intercepted in January. In the telegram, sent by German foreign minister Alfred Zimmermann to his ambassador in Mexico on January 16, Zimmermann instructed the ambassador to offer Mexico generous financial aid if it would ally itself with Germany against the United States. Furthermore, the telegram promised German support for Mexico in reconquering its lost territory in Texas, New Mexico, and Arizona.

On March 1, 1917, the text of the Zimmermann Telegram appeared on the front pages of American newspapers, and in a heartbeat, American public opinion shifted in favor of entering the war.

The U.S. Declaration of War

Although Wilson tried hard to keep the United States neutral, by the spring of 1917, the situation had changed significantly, and neutrality no longer seemed feasible. Germany’s unrestricted submarine warfare was taking its toll, as American ships, both cargo and passenger, were sunk one after another. The exposure of the Zimmermann telegram and other German subterfuge further convinced the American public that the war was threatening American interests. Finally, on April 2, Wilson appeared before Congress and requested a declaration of war. Congress responded within days, officially declaring war on Germany on April 6, 1917.

The Convoy System

By the time the United States entered the war, German submarines were causing catastrophic damage to the supply of food and other resources coming into Britain from abroad. On May 24, 1917, the British admiralty finally gave in to demands to establish a system of Convoys. Under the plan, British warships would provide heavily armed escorts for all ships coming to Britain from the United States, Canada, and other countries. The plan was especially important from the U.S. perspective, as American soldiers would soon begin heading to Britain by ship in large numbers. More than half a dozen convoy gathering points were soon established along the North American coast.

The convoys had an immediate and dramatic effect. The number of ships, supplies, and men lost to German submarines plummeted, virtually nullifying Germany’s effort to force Britain’s surrender. There was a downside, however, as it meant that Britain now had far fewer naval assets available to protect its coast or to engage the German navy at sea.

Arrival of U.S. Troops in Europe

All through the summer of 1917, U.S. troops were ferried across the Atlantic, first to Britain and then on to France, where they came under the leadership of General John J. Pershing. The first public display of the troops came on July 4, when a large U.S. detachment held a symbolic march through Paris to the grave of the Marquis de Lafayette, the French aristocrat who had fought alongside the United States during the American Revolution.

First U.S. Combat Involvement

Though U.S. leaders had not planned major military involvement until the summer of 1918, some forces saw combat in the fall of 1917. The first American fatalities on the ground in Europe occurred on September 4, when four soldiers were killed during a German air raid. The first full-fledged combat involving U.S. troops happened on November 2–3, 1917, at Bathelémont, France; three were killed and twelve were taken as German prisoners of war.

Wilson’s Fourteen Points

On January 8, 1918, President Wilson gave a speech before the U.S. Congress in which he defined a total of fourteen distinct requirements that he saw as necessary in order to restore and maintain peace in Europe and the rest of the world. The requirements soon came to be known simply as Wilson’s “Fourteen Points.

Some of these points—such as the evacuation of German troops from Russia, France, and Belgium—were basic steps necessary for ending hostilities; other points were part of a long-range vision for preventing future conflicts. Among these long-term points was a suggestion that diplomacy and treaties always be carried out openly and in full public view. Wilson further suggested that all economic barriers be eliminated and that all nations adopt an “equality of trading conditions.” The final, fourteenth point called for establishing a “General Association” of the world’s states, with each to have equal representation regardless of size or strength. Although the details of Wilson’s plan would be adjusted considerably over time, his proposals laid the foundation for the armistice negotiations that would take place ten months later.

Assessing the U.S. Entrance

In the year leading up to the U.S. declaration of war, President Wilson’s position on the war changed dramatically. Although the United States had long maintained a much warmer relationship with Great Britain and France than with Germany or Austria-Hungary, Wilson’s administration kept a strictly neutral stance. Moreover, as Wilson began making diplomatic initiatives in 1916, his position toward the Central Powers was considerably more lenient than the Allies were comfortable with.

This evenhanded diplomacy evaporated quickly, however, when Germany lifted its restrictions on submarine warfare in January 1917. Although it was the Zimmermann telegram that effectively turned American public opinion, in truth, the “threat” presented in the telegram bordered on the absurd. The threat from German submarines, on the other hand, was a direct threat to American lives, commerce, and property and had to be countered. There could now be little question of the United States remaining neutral, and within two months, the United States declared war.

At it turned out, there was a large time gap between the U.S. declaration of war and the actual entrance of U.S. troops in combat on the front. The U.S. Army was not the vast and flexible force that it is today, and much time would be needed for large numbers of U.S. soldiers to be trained, moved into place, and organized. Even after troops were finally in combat, the United States never formally joined the Allied forces but technically remained an independent participant, at war only with Germany and not with Austria-Hungary.