Communism and other utopian one-worldisms have time and time again - without exception - degenerated into some or other form of nationalism.
Internationalism is the opium of urban intelligentsia completely out of tune with the masses of their own people, and as soon as the commoners - the rural masses historically - have anything to say about how things are run, the state once again becomes the handmaiden of the tribe.
Or to put it another way, people do not enlist, endure, fight and die for airy abstractions - they always do so for "blood and soil."
But instead of anymore of the usual rambling prose, I'll quote some verse for once.
Yeats wrote a nice poem on this, "An Irish Airman Foresees His Death":
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I know that I shall meet my fate,
Somewhere among the clouds above;
Those that I fight I do not hate,
Those that I guard I do not love;
My country is Kiltartan Cross,
My countrymen Kiltartan's poor,
No likely end could bring them loss
Or leave them happier than before.
Nor law, nor duty bade me fight,
Nor public men, nor cheering crowds,
A lonely impulse of delight
Drove to this tumult in the clouds;
I balanced all, brought all to mind,
The years to come seemed waste of breath,
A waste of breath the years behind
In balance with this life, this death.