The sinking of the Lusitania by German U-boats was the key event that led the United States into World War I. Although other incidents, such as the Zimmerman telegram, precipitated U.S. involvement, the Lusitania was the most visible symbol of anti-American aggression.

"Remember the Lusitania." 1915. World War I Propaganda Poster. Courtesy the Library of Congress, Washington, DC.




The U.S. military employed a large recruitment effort to mobilize the nation for war. Troops would reach Europe by 1918, under the command of General John J. Pershing. http://hdl.loc.gov/loc.pnp/cph.3g11355

"Men Wanted for the Army." World War I Propaganda Poster. Courtesy The Library of Congress, Washington, DC. http://hdl.loc.gov/loc.pnp/cph.3g10143



Trench warfare characterized much of the war. Compounded by new inventions such as the machine gun, barbed wire, and fighter planes, Americans were not spared these horrors of the war.

"In the trench near San Marco during action of May 12, 1917." Ca. 1917. World War I Photograph. Courtesy The Library of Congress, Washington, DC.
http://hdl.loc.gov/loc.pnp/cph.3a51388





America's contribution to the war proved decisive, and an armistice was signed on November 11th, 1918. Over 20 million had died in the war, including 117,000 Americans.

"The Dawn of Democracy." 1918. World War I Propaganda Print. Courtesy The Library of Congress, Washington DC. http://hdl.loc.gov/loc.pnp/cph.3b43955






In 1919, Wilson traveled to Europe to meet with Allied heads of state Lloyd George (England), Georges Clemenceau (France), and Vittorio Orlando (Italy). The Conference would determine the political future of Europe for two decades.

"Council of Four of the Peace Conference. Mr. Lloyd George; Signor Orlando; M. Clemenceau; President Woodrow Wilson. Hotel Crillon, Paris, France." 05/27/1919. Courtesy of The National Archives, Washington, DC. http://arcweb.archives.gov/arc/arch_results_detail.jsp?&pg=1&si=0&st=b&rp=digital&nh=1