The leader of Russia's Bolshevik Revolution, Lenin was the world's most famous Socialist while Debs was opposing World War I and going to jail for his speeches that urged workers to see the war as a capitalist ploy.

For his part, Lenin fiercely opposed Russia's involvement in the war and took Russia out of the action as soon as he solidified his power. Debs was super-hopeful, at first, about the Russian Revolution creating a real workers' paradise, and for many months his thinking about America's workers was influenced by the events in Russia. During this time, he at first tried to develop an American Socialist policy that would be supportive of Russia's revolution.

Lenin said nice things about Debs and vice versa—at first. When all of his Socialist buddies were telling Debs how great he was for being willing to go to jail, Debs himself said that his deeds were "almost contemptible" when compared to Lenin.

Back at him, Lenin called Debs "a fearless man…a true representative of the revolutionary proletariat" (source).

But while he was in prison, Debs leaned about some of the harsh things that Lenin and his Bolsheviks were doing to their political opponents in Russia. He was horrified when the czar and his family were murdered and sent a telegram to Lenin in 1922 protesting more murders of political enemies.

Debs continued to praise the ideal of creating a workers' republic, but what Debs was envisioning was democratic, not authoritarian. He and Lenin saw Socialism taking very different paths.