The First World War began as a conflict between Austria-Hungary and Serbia. Austria-Hungary, encouraged by its German ally, declared war on Serbia on August 4, 1914, in retribution for the June 28 murder of the Austrian heir to the throne by a Serbian national. Treaties of alliance expanded the number of nations at war, for Russia then mobilized on behalf of its Serbian ally and Germany on behalf of Austria. In reality, Germany wanted a war in Europe so that it could access open trade routes by seizing territory during the fighting that would extend its national borders to the Atlantic Ocean. Germany implemented its plan by invading Luxembourg and then declaring war on France and Belgium, which drew Great Britain into the war because of its alliances with the two latter nations. Other nations recognized that a world war offered opportunities for political and territorial gains, and by the end of 1914, the alliances expanded what was originally a limited war between Serbia and Austria-Hungary into a larger European conflict that pulled in nations and colonies in the Middle East, Africa, Asia, and North America.
From the start of the war until April 1917, the U.S. was officially neutral. Most Americans believed that the nation’s neutral position did not prohibit them from taking sides in the European war, but rather allowed them to support either Germany or the Allies.
Germany drew the U.S. into the European conflict when it attempted to break the stalemate with Great Britain that had prevented either nation from making significant gains in the trench war in 1915 or 1916. Great Britain had weakened Germany with a blockade in the English Channel that kept supplies from reaching its enemy. Germany then attacked any British ship carrying military supplies on the Atlantic Ocean. One such attack in May 1915 on a passenger liner, the Lusitania, killed 124 Americans and caused American public sentiments to shift discernibly in favor of the Allies. Although the relationship between the U.S. and Germany deteriorated, it remained intact until Germany expanded its assaults to all vessels bound for Great Britain regardless of their nation of origin on February 1, 1917. This unrestricted submarine warfare—during which Germany attacked neutral U.S. ships—prompted President Woodrow Wilson to sever diplomatic relations with Germany, and many Americans believed war was imminent. The relationship between the U.S. and German governments changed almost “overnight,” and Germany’s actions increased anti-German sentiments and solidified American public support for Great Britain and the Allies.
When Wilson asked Congress to declare war against Germany, he offered Americans a way to understand the war as a defensive act to protect American citizens. In his joint address to Congress on April 2, 1917, the president described how German submarines, intending to cripple commerce to Great Britain and her allies, attacked and sunk American ships and killed American citizens. These acts violated international laws that granted free passage to every nation on the seas. Wilson called Germany’s actions “warfare against mankind” and asserted that to do nothing was to submit to these violations of Americans’ rights. He did not, however, ask Congress to declare war on Germany; instead, he asked that Congress recognize Germany’s attacks on American ships in the Atlantic as acts of war and declare that a state of war existed between the two nations. Wilson’s language allowed him to position the U.S.’s entry into the European conflict as a defensive action undertaken to protect Americans from German aggression. Four days later, on April 6, 1917, both the U.S. House of Representatives and the Senate approved the president’s request.
President Wilson ran for re-election in 1916 with the campaign slogan, “He kept us out of war.” Yet only weeks after his second ?inauguration, he stood in front of Congress to send the nation to war.
From the Mt. Vernon, Ohio, Democratic Banner, November 3, 1916.
 Martin Gilbert, The First World War: A Complete History (New York: Henry Holt and Co., 1994), 6-7, 18-33, 46, 79, 105.
 Petra DeWitt, Degrees of Allegiance: Harassment and Loyalty in Missouri’s German-American Community during World War I (Athens, OH: Ohio University Press, 2012), 42.
 Frederick C. Luebke, Bonds of Loyalty: German-Americans and World War I (De Kalb, IL: Northern Illinois University Press, 1974), 130-134.
 Gilbert, First World War, 306-318.
 David Detjen, The Germans in Missouri, 1900-1918: Prohibition, Neutrality, and Assimilation (Columbia, Missouri: University of Missouri Press, 1985), 101-102; Luebke, Bonds of Loyalty, 84-5, 200-201; Byron Farwell, Over There: The United States in the Great War, 1917-1918 (New York: W.W. Norton & Company, 2000), 28. Quote in Luebke, Bonds of Loyalty, 200.
 President Woodrow Wilson, “Joint Address to Congress Leading to a Declaration of War Against Germany,” April 2, 1917, RG 46, Records of the United States Senate, 1789-2011, Journals and Minute Books, compiled 1797-1968, National Archives and Records Administration, Center for Legislative Archives, Washington, DC.
 David M. Kennedy, Over Here: The First World War and American Society (New York: Oxford University Press, 1980), 20.