The nationalist fervor that characterized the prewar conditions of the early 20th century could be seen as a defensive posture on the part of numerous ethnic groups across the world. What people were realizing is that their civil rights would not be respected unless they had guns pointed at their would-be oppressors, and they wanted control of a state that could be used to both jack into capitalist markets and protect them from those markets at the same time.
Hannah Arendt for example observed that refugees and stateless peoples were treated worse than criminal citizens; they were viewed as subhuman and disposed of as such. It took having a nation to one's name to be coded as a citizen and therefore able to enjoy the protection of basic human rights, guaranteed by none other than a state which considered its resources best placed in its identifiable citizens.
This isn't an argument for nationalism. It is however the sort of logic that unfolds when a national empire - or multiple empires - exists. And having a nation doesn't even guarantee one's protection if the ruling class sees one fit for marginalization in any way.
