By Patrick Allitt, Emory University
When WWI began, America had maintained a neutral stance. But, when more than 100 Americans died on the British liner Lusitania—sunk by a German submarine in 1915—American public opinion swung sharply toward a British alliance. President Woodrow Wilson was reelected in 1916 under the slogan, “He kept us out of war”. But, no sooner had he been re-inaugurated than the German decision to declare unrestricted submarine warfare in the Atlantic on American ships led him to declare war against Germany.

America’s Call for Peace
This was a conflict, clearly, from which the Americans could stay aloof, and ought to do so if possible. President Wilson urged Americans to be neutral in thought and deed. He said, in an early speech in 1914, “It would be a calamity to the world at large if we should be drawn actively into this conflict, and so deprived of all disinterested influence over the settlement.”
What he hoped was that eventually the warring powers would come to their senses and that he, as the President of America, would be able to preside over a benign and enlightened peace treaty. Many Americans were ardent pacifists. Andrew Carnegie was a famous one. Jane Addams, who ran the Hull House Settlement House, was another. One of her friends, Lillian Wald, also a settlement worker, organized a great peace march in the streets of New York City to protest against this catastrophe of war.
This is a transcript from the video series A History of the United States, 2nd Edition. Watch it now, on Wondrium.
Germany’s Unrestricted Submarine Warfare
America’s direct participation in the war became inevitable early in 1917, and it had a decisive effect on the outcome. President Wilson was running for reelection in the fall of 1916, and he ran under the slogan, “He kept us out of war”, However, he himself said to his advisors, “I can’t keep the country out of war. They talk of me as though I were a god. Any little German lieutenant can put us into the war at any time by some calculated outrage.”

Well, by the time of Wilson’s second inauguration, Germany itself had decided to commit unrestricted submarine warfare against America, because its aid to Britain and France was already immense. From the German point of view, every American ship crossing the Atlantic ocean with goods destined for France or Britain really was helping the British war effort, and making the defeat of Germany that much more possible.
German Point of View
German leaders speculated that declaring war on America would actually aid their cause. Here’s one of the German generals, Erich von Falkenhayn, writing a letter to the German Prime Minister, Theobald von Bethmann Hollweg. He said,
I consider unrestricted U-boat warfare not only one, but the only effective instrument of war at our disposal capable of bringing England to consider peace negotiations. So far as the situation is concerned, America’s step from secret war in which it has long been engaged against us, to an openly declared general hostility can effect no real change.
He said it might even help, because now America was going to start building up its own armed forces, so that the goods it was sending across the Atlantic at the moment, it would now be tempted to keep within the nation, as it began its own buildup. At that point, the American military was very small, relative to the forces already engaged in Europe.
The German politicians could, therefore, foresee that American entry into the war wouldn’t immediately have any adverse military consequences, and could actually provide a breathing space for them.
America’s Official Declaration of War
Well, Wilson still delayed in the early months of 1917, realizing the potentially catastrophic effects of sending America directly into the fighting. He said:
Once we lead these people into war, they’ll forget there ever was such a thing as tolerance. To fight, you must be brutal and ruthless, and the spirit of ruthless brutality will enter into the very fiber of our national life, infecting Congress, the courts, the policemen on the beat, the man on the street.
America did officially declare war against Germany at the beginning of April 1917.
A Losing Battle?
Now, the Germans’ policy of unrestricted submarine warfare at first was very successful. British and American ships suddenly were being sunk very rapidly. It caused a terrible concern to the naval commanders.
The head of the American Navy, Admiral Sims, crossed the Atlantic, and met with his British counterpart, Admiral Jellico, the head of the Royal Navy, and they discovered that in the first 10 days of April 1917, 250,000 tons of British and American shipping had been sunk; a quarter of a million tons just in those 10 days.
Consequently, just as the Americans came into the war, it seemed terrifyingly possible that the war was going to be lost.
Common Questions about Why America Entered the World War I
At the outset of the war, President Woodrow Wilson urged Americans to be neutral in thought and deed. He said, in an early speech in 1914, “It would be a calamity to the world at large if we should be drawn actively into this conflict, and so deprived of all disinterested influence over the settlement.”
America officially declared war against Germany at the beginning of April 1917.
German leaders speculated that declaring war on America would actually aid their cause. They could foresee that American entry into the war wouldn’t immediately have any adverse military consequences, and could actually provide a breathing space for them.