 That nationalist betrayal of socialism was denounced by a small group of socialist leaders who opposed the Great War, including Rosa Luxemburg, Karl Liebknecht and Lenin, who said that the European socialists had failed the working classes for preferring patriotic war to proletarian internationalism.To debunk patriotism and national chauvinism, Lenin explained in the essay "Imperialism, the Highest Stage of Capitalism" (1917) that capitalist economic expansion leads to colonial imperialism which is then regulated with nationalist wars such as the Great War among the empires of Europe.To relieve strategic pressures from the Western Front (4 August 1914 – 11 November 1918), Imperial Germany impelled the withdrawal of Imperial Russia from the war's Eastern Front (17 August 1914 – 3 March 1918) by sending Lenin and his Bolshevik cohort in a diplomatically-sealed train, anticipating them partaking in revolutionary activity.