Marx’s thought on nationhood emerged from the cosmopolitan legacy of the “radical Enlightenment.” It took shape in the crucible of European nationalisms, the persistence of dynastic multinational empires, and the appearance of socialism as a new political actor.1 In 1848, the national question was deeply intermingled with the question of class. As a minority current of socialism, at least until the end of the nineteenth century, Marxism promoted a new form of political internationalism of which the most significant expression was the foundation of the International Workingmen’s Association in 1864. A constitutive tension quickly appeared between this cosmopolitan aspiration – well synthesized by The Communist Manifesto’s sentence: “the workers have no country”2 – and the growing tendency of the nascent socialist movements to inscribe themselves into national patterns made of inherited cultures, languages, traditions, and social practices.