"Fascism was created by the nationalization of certain sectors of the revolutionary left, and the central role in its conceptual orientation was played by revolutionary syndicalists who embraced extreme nationalism. Revolutionary syndicalists, especially in Italy, were frequently intellectuals or theorists who had come out of the Marxist and Socialist party matrix but had struggled to transcend limitations or errors that they believed they found in orthodox Marxism."
https://en.wikiquote.org/wiki/Fascism's_relationship_with_other_political_and_economic_ideologies