The dictatorships of Hitler and Stalin were the two most lethal regimes in history and the protagonists of the most devastating war humanity has ever known. Despite the multiple parallels and similarities that have been established between National Socialism and Communism - the sick cult of the leader, the promises of a utopian future, terror as a political weapon or the absolute denial of individual freedoms and rights - the historian Richard Overy analyzes the undoubted differences between the two systems, such as the emphasis that Hitler placed on nationalism and Stalin on the proletarian struggle against the bourgeoisie.