Marx was an internationalist, who believed in the primacy of the productive forces and the centrality of class struggle. He wrote little directly on nations and nationality, but what he did write was with clarity and common sense. His most widely quoted passages, unfortunately, have been mistranslated and misinterpreted. Interpreters’ confusions about internationalism, universalism, the state, and globalization continue to affect the understanding of nationalism in Marx’s work and elsewhere. For Marx, nations were important in capitalism and in transitional societies and would be in future communism. Some aspects of nations were made explicit by Marx, while others clearly fit his developed ideas. There is no reason to think that Marx would expect people to abandon their nation and nationality in seeking communism.
Marx, Engels, and Marxisms
Department of Philosophy

Ware, R.X. (2019). Nationalism and internationalism. In Marx on Emancipation and Socialist Goals (pp. 115–140). doi:10.1007/978-3-319-97716-4_7