Socialism in the U.S During WWI

During World War I, Woodrow Wilson passed the Espionage, Sabotage, and Sedition Acts all in the name of restricting the voice of dissenters who opposed American involvement in the war. Wilson feared the power of groups like the anarchists, pacifists, civil libertarians, and most notably, socialists.
In the years leading up to World War I, the Socialist Party had made significant strides on the political scene. Led by the controversial Eugene Debs, the socialists gained seats in Congress as well as in numerous local government positions in the elections of 1910 and 1912. Also, Eugene Debs' campaign in the 1912 presidential election resulted in 6% of the popular vote, a significant number for any third party. This newfound popularity of socialism reflected and reinforced a more pacifistic side of the U.S, which led to a considerable rift in American society in the increasingly militaristic years of 1915 and 1916.
This rift was most noticeable in the socialist capital of the U.S at the time, Seattle. As the government encouraged preparedness for the war, parades were thrown around the city to aid this. In response, the socialists (and other anti-war activists) held gatherings to protest these parades. In addition, these socialists sent a resolution to Congress that would end American militarism and deal with the war in a pacifistic way.
When Woodrow Wilson finally declared war in 1917, American socialists increased their efforts in resisting intervention in Europe. Socialists were encouraged to publicly voice their anti-war sentiments and disrupt conscription. They printed anti-war pamphlets and held mass gatherings to denounce American militarism. These socialists also sent letters to congressmen and Wilson to convince them to stop the war effort.
In response to these anti-war movements, mainstream media denounced these anti-war activists as un-American and German sympathizers. Wilson also sought to limit the influence of these activists with his passing of the Espionage and Sedition Acts. The Espionage Act made encouraging disloyalty to America and interfering with conscription illegal. The Sedition Act made denouncing America or its military illegal. The government prosecuted over 2,100 people with these acts, and discouraged thousands more from voicing their anti-war sentiments. Prominent socialists like Eugene Debs and Kate Richards O'Hare were some of the more influential victims of these acts. These acts, along with the propaganda against anti-war activists, effectively killed the socialist movements in the U.S in this time period.

http://www.u-s-history.com/pages/h1669.html
http://depts.washington.edu/antiwar/WW1_reds.shtml
http://www.digitalhistory.uh.edu/disp_textbook.cfm?smtID=2&psid=3479