No prominent European socialist before World War I resembled Lenin more closely than Benito Mussolini. Like Lenin, he headed the antirevisionist wing… - Richard Pipes

The French Jacobins were the first to realize the political potential of class resentment. Exploiting it, they conjured constant conspiracies by aristocrats and other enemies of the revolution: shortly before their fall they drafted legislation expropriating private wealth and had the unmistakable communistic implications. It was from the study of the French Revolution that its aftermath that Marx formulated the theory of class struggle as the dominant feature of history. In his theory, social antagonism was for the first time accorded moral legitimacy: hate, which Judaism condemned as self-destructive, and Christianity (in the guise of anger) treated as one of the cardinal sins, was made into a virtue.

The Nazi appealed to the socialist traditions of German labor, declaring the worker ‘a pillar of the community,’ and the ‘bourgeois’—along with the traditional aristocracy—a doomed class. Hitler, who told associates that he was a ‘socialist,’ had the party adopt the red flag and, on coming to power, declared May 1 a national holiday; Nazi Party members were ordered to address one another as ‘comrades (Genossen). His conception of the part was, like Lenin’s, that of a militant organization a Kampfbund, or ‘Combat League.’

Given the opportunity, Mussolini would have been glad as late as 1920-21 to take under his wing the Italian Communists, for whom he felt great affinities: greater, certainly, than for democratic socialists, liberals and conservatives. Genetically, Fascism issued from the 'Bolshevik' wing of Italian socialism, not from any conservative ideology or movement.