For the geopolitical jackass

 Nationalism in the period from the French Revolution until approximately World War I could play an historically progressive or even revolutionary role (i.e. in the era of bourgeois revolutions) when the formation of viable nation states out of the old dynastic order 

(ie States out of the old dynastic order (e.g. Germany, Italy) 

was still possible. This said, the “right of nations to self-determination” was never, as an abstract principle, part of the revolutionary tradition separate from a geopolitical-strategic orientation to the unification of the working class, which is always an international class. Marx supported Irish nationalism against British rule, and Polish nationalism against Russian rule, but opposed Balkan nationalism that might weaken the Ottoman bulwark against Russian expansionism. . . "

Marx To Engels, 12 September 1863: "The most interesting acquaintanceship I have struck up here is that of Colonel Lapinski. He is without doubt the cleverest Pole - besides being an homme d'action [man of action] - that I have ever met. 

His sympathies are all on the German side, though in manners and speech he is also a Frenchman. 

He cares nothing for the struggle of nationalities and only knows the racial struggle. He hates all Orientals, among whom he numbers Russians Turks, Greeks, Armenians, etc., with equal impartiality.... 

His aim now is to raise a German legion in London, even if only 200 strong, so that he can confront the Russians in Poland with the black, red and gold flag, partly to 'exasperate' the Parisians, partly to see whether there is any possibility whatsoever of bringing the Germans in Germany back to their senses. What's lacking is money. Efforts are being made down here to exploit all the German societies, etc., to this end. You must be the best judge of whether anything can be done in this line in Manchester. The cause itself would seem to be above reproach.”