On September 11, 1915, at Zimmerwald in Switzerland, delegates to the First International Socialist Conference call for an immediate end to the First World War.
Even as battle dragged on in the trenches of the Western Front and the war in the air intensified with increased German air strikes on London and its environs, a group of dedicated anti-war activists and committed socialists gathered in neutral Switzerland from September 5 to 11, 1915, as the First International Socialist Conference. Formally assembled by the Swiss and Italian Socialist parties, the conference included some 40 delegates from 11 countries, including Russia, Poland, France, Germany, Bulgaria, Romania, Italy, Switzerland, the Netherlands, Sweden and Norway. Among the more prominent attendees were Vladimir Lenin, exiled leader of the radical socialist Bolshevik Party; Leon Trotsky, Lenin’s former political rival and future second-in-command; and Karl Liebknecht, an elected representative to the German Reichstag government who would later break from the Social Democratic party to found the Bolshevik-inspired Spartacist movement with Rosa Luxemburg.
According to the conference’s manifesto, "the war which has produced this chaos is the outcome of imperialism, of the attempt, on the part of the capitalist classes of each nation, to foster their greed for profit by the exploitation of human labor and of the natural treasures of the entire globe." In order to force an immediate end to the war, the conference insisted, workers within each country should try by any means necessary to convert the current capitalist struggle into a more enlightened one: an international workers’ revolution or civil war "between the classes" that would spread throughout Europe, and eventually the world.
Two years later, with revolution in full swing in Russia and Czar Nicholas II off the throne, Lenin returned to Russia from exile—smuggled in with the help of the Germans—to carry out what he saw as the first step in fulfilling the resolution decided upon at the Zimmerwald Conference. After seizing control of Russia from the provisional government, he and Trotsky consolidated power for the Bolsheviks, declaring an immediate armistice with the Central Powers and pulling Russia out of World War I by the end of 1917.