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The United States in World War I

World War I was the "war to end all wars." It had major consequences on Americans both at home and abroad. 


  • World War I was the deadliest conflict until that point in human history, claiming tens of millions of casualties on all sides.
  • Under President Woodrow Wilson, the United States remained neutral until 1917 and then entered the war on the side of the Allied powers (the United Kingdom, France, and Russia).
  • The experience of World War I had a major impact on US domestic politics, culture, and society. Women achieved the right to vote, while other groups of American citizens were subject to systematic repression.

War in Europe and US neutrality

On June 28, 1914, Yugoslav nationalist Gavrilo Princip assassinated the heir to the throne of the Austro-Hungarian empire, Archduke Franz Ferdinand. Princip and his accomplices wanted to unite the Yugoslav people and liberate them from Austrian rule. The assassination set off a series of events that culminated in a declaration of war between Austria-Hungary and Serbia. Due to the European alliance system, all major European powers were drawn into the war, which spread around the globe and became the first world war in human history.1
Map of World War I combatants
World War I was truly a world-wide war. Here, countries that were allied with the Triple Entente, known as the Allied Powers, are highlighted in green. Countries that were allied with the Central Powers are highlighted in orange. Map courtesy Wikimedia Commons.
The war pitted two groups of allies against each other: the Triple Entente, composed of Russia, France, and the United Kingdom, against the Central Powers, Germany and Austria-Hungary.
Though everyone believed the war would be quick and decisive, it instead bogged down in a prolonged war of attrition, with soldiers in the trenches fighting ferociously to move the battle lines by mere inches.2

The United States enters World War I

US President Woodrow Wilson sought to maintain US neutrality but was ultimately unable to keep the United States out of the war, largely because of escalating German aggression. On May 7, 1915, the Germans sunk the British ocean liner RMS Lusitania, which had over a hundred Americans on board. Wilson warned that the United States would not permit unrestricted submarine warfare or any further violations of international law.
In January 1917, the Germans resumed submarine warfare. A few days after this announcement, the Wilson administration obtained a copy of the Zimmermann Telegram, which urged Mexico to join the war effort on the side of Germany and pledged that in the event of a German victory, the territories of Arizona, Texas, and New Mexico would be stripped from the United States and returned to Mexico. The publication of the Zimmermann Telegram and the escalation of German submarine attacks on US merchant vessels led the US Congress to declare war on Germany on April 6, 1917.
More than 1.3 million men and twenty thousand women enlisted in the armed forces.3 Though some Americans opposed US entry into the war, many believed they had a civic duty to support the war effort. US government propaganda sought to mobilize the American citizenry through appeals to patriotism and civic duty, and by linking US democracy with support for the democracies of Western Europe.
Propaganda poster for the American war effort in World War I, 1917. The poster portrays Germany as a mad gorilla that would turn its sights on American shores if not defeated in Europe. Image courtesy Wikimedia Commons.
The Selective Service Act of 1917 authorized the conscription of military manpower for the war effort so that the United States did not have to rely solely on volunteers.4 Because many American citizens believed it was their patriotic duty to support the war effort, the draft was well-received and rates of draft-dodging were relatively low.

World War I on the home front

The First World War had an enormous impact on US politics, culture, and society. Advocates of female suffrage successfully linked the patriotic efforts of women in the war with voting rights. This strategy was highly effective, and in 1920, the US Congress ratified the Nineteenth Amendment, which guaranteed women the right to vote.5
Others were not so lucky. Hyper-vigilance on the home front led to spontaneous outbreaks of violence against groups whose loyalty to the United States was considered suspect. German-Americans, labor activists, suffragists, immigrants, African Americans, and socialists were subjected to threats, harassment, imprisonment, and physical violence.
At the same time, civil liberties were sharply curtailed. The Espionage Act of 1917 and the Sedition Act of 1918 criminalized the expression of antiwar sentiment and criticism of the US government and armed forces. Voluntary associations were created to identify dissidents, and many of these worked together with the Federal Bureau of Investigation to patrol the home front and punish perceived “enemies.”6

Aftermath: consequences of World War I

The experience of the First World War was traumatizing. The so-called “civilized” Western democracies had plunged into a ferocious and deadly conflict with uncertain origins and an unsatisfying outcome. As a result, many became disillusioned with the values and ideals of American political democracy and consumer culture. The generation that came of age during the First World War and the “Roaring 1920s” is known as the “Lost Generation.”
On the political front, a debate erupted between President Wilson and his supporters, who sought an expanded role for the United States in world affairs, and isolationists in Congress, who feared becoming embroiled in future European conflicts. Though Wilson was the foremost advocate of the League of Nations, an international peacekeeping organization, the United States never officially joined the League due to isolationist opposition.7

What do you think?

Why was President Wilson unable to keep the United States out of the war?
What was the effect of the war on US culture and society?
Were the domestic effects of the war more positive or negative overall?
Should the United States have joined the League of Nations?

Want to join the conversation?

  • blobby green style avatar for user arnaud.alain
    It says: "World War I was the deadliest conflict in human history." Wasn't WWII the deadliest one?
    (20 votes)
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    • leaf green style avatar for user Appfaninmarion
      World War II was more of a "total war" than WW I, in that millions of civilians were killed in WW II by bombing of cities and industrial locations, while in WW I most of the deaths were related to direct combat. Total casualties were greater in WW II, but there were more direct combat related deaths in WW I.
      (62 votes)
  • duskpin seed style avatar for user nmmendoza
    why did the Mexicans refused the germans telegram
    (11 votes)
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    • leaf orange style avatar for user Alexis
      The Zimmermann Telegram is "proven" to be real and sent to Mexico, but then again all this proof was discovered by the British, and other proof of the letter was found in the UK. Arthur Zimmermann publicly confirmed the telegram, but if you think about it, that could be bogus, too. The truth is, we just will never know the true legitimacy of the telegram, no matter how much you want to argue it. Technically, Mexico has never been that strong or prominent of a nation, and I'm guessing that they knew that a war with the U.S. would lead to more damage for them (and increase in racism from part of the whites). Why Germany would chose to contact Mexico is open to question, and a very arguable matter. Some people believe that the ZImmermann Telegram was just an excuse for the U.S. to enter into the war, while others argue that it is what we are told it is. Mexicans could have refused the telegram for 2 reasons. If it was fake, there was nothing to agree to in the first place (Even if they didn't know that. They might or might not have been told, more likely not). And the second reason is that the U.S. already fully occupied the lands Mexico would "get back", and that the U.S. was a lot more powerful (in military, population, government, etc.) than them. This leads us to the original prospect as to why might the telegram be fake. Germany knows very well that Mexico is unable to compete with the U.S. and get their lands back. It may just have been that they wanted more people on their side, and thought this to be an effective form of bribery to get Mexico to fight alongside them. Then again, it may have been made only to anger U.S. and get them to join the war (something Germany would not have wanted, and thus would not have made themselves). Either way, both sides are reasonably arguable. One thing that is pretty obvious however, is that joining the war would more than likely not have benefited Mexico whatsoever, and is why they didn't join.
      (50 votes)
  • leafers sapling style avatar for user RyanTCHGao
    Why did the assassination of Archiduke Franz Ferdinard effect the war that much?
    (3 votes)
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    • aqualine ultimate style avatar for user Jude
      I forget exactly how it goes, but basically, everyone is allied with somenone else (except America) and that someone is allied with another somone, and so on and so forth. So, if one attacks a country, one is attacking many countries.
      (17 votes)
  • starky tree style avatar for user Zob Rombie
    Looking at the map highlighting the Allied Powers and the Central Powers, its not hard to notice that the German colonies of Cameroon, East and West Africa, Togoland, and Somoa are all far from Germany herself and were surrounded by Allied nations. Not to mention that Kiautschou Bay was located deep in Chinese territory. With the exception of the Somoas that span the Pacific, which even they were within Allied reach, all of Germany’s territories outside of the mainland were practically defenseless against the Allies. How long did those colonies remain in German claim during the war? And did they have any support from the mainland?
    (8 votes)
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  • blobby green style avatar for user purlscoutk1d2
    what was world war 1's effect on Americas government?
    (9 votes)
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  • male robot hal style avatar for user portere
    Why is WW1 called "The War to End all Wars" when it did nothing BUT that considering WW2 started eh, 20, 15, years later?
    (4 votes)
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  • marcimus orange style avatar for user gkyttle98
    What role did the U.S. play in determining the outcome of WW1?
    (7 votes)
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  • aqualine ultimate style avatar for user EllaCinder18
    Who did many Americans view as their biggest enemy after World War I?
    (5 votes)
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  • blobby green style avatar for user Amirah Bonner
    How did the US government encourage Americans on the home front to support the US war effort in Europe?
    (3 votes)
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    • aqualine tree style avatar for user David Alexander
      The US government directed a great deal of propaganda at the populace in the states to promote support of the war effort. There were patriotic movies, and "anti-enemy" movies, too. There were campaigns to get people to loan money to the government, and others to encourage enlistment in the armed forces and merchant marine. There were resource recovery drives and things like victory gardens. The gardens didn't support the frontline soldiers, but were considered a way that citizens, by growing their own food, could leave that which was grown commercially to be used for the military.
      (5 votes)
  • blobby green style avatar for user abbygail j.o
    what was the reaction of the civilians in the US, when USA entered the war?
    (3 votes)
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    • leaf yellow style avatar for user PI Technology Π
      It depended on the race. The people with British heritage or French heritage believed in supporting their country. When America joined the war on the allies side they where happy. And historically a lot of Americans fled led to support the allies because of history both of the French and British. The German-Americans felt led to support their fatherland so they were not happy when America sided with the allies. The Jewish-Americans and Polish-Americans disliked Russia so they probably were not happy when America sided with the allies. I think that also a lot of Americans in general disliked the idea of America becoming involved in a world war, as a matter fact many men resisted the draft and Eugene v. Debs was jailed for encouraging men to resist the draft. Overall I think the feelings were very mixed when America entered the war.
      (4 votes)