Nationalism
Nationalism, or bourgeois nationalism, is a political ideology advocating against internationalism and for the national bourgeoisie (versus the international proletariat). This is not to be confused with proletarian patriotism, that is, valuing the contributions of the proletariat of a particular country. The classics of Marxism-Leninism were all opposed to nationalism:
"An alliance between the working class and the working peasantry within the nation for the elimination of the survivals of capitalism in order that socialism may be built triumphantly; [...] elimination of the survivals of nationalism in order that friendship may be knit between the peoples and internationalism firmly established [...]"[1]
"Marxism cannot be reconciled with nationalism, be it even of the “most just”, “purest”, most refined and civilised brand."[2]
"Whether the proletariat rallies to the banner of bourgeois nationalism depends on the degree of development of class antagonisms, on the class consciousness and degree of organisation of the proletariat. The class-conscious proletariat has its own tried banner, and has no need to rally to the banner of the bourgeoisie."[3]