And in contrast, this thread's point: that attempts to unify disparate cultures via democracy and mutual agreement, celebrating differences, have difficulties and failures when constituents decide to abandon good faith.
The idea that nation states are old, and multinationalism is new is fallacious. It's only post WWII that borders, political control, and ethnic homogeneity are strongly national... Yugoslavia being the most recent example.
I would love to (interested in the topic)
First national exhibition hosted by the Vichy government during occupation: “la France europeenne”. Showing maps of future europe, where nation-states would have disappeared.
French far-right at the time was also calling England, “the enemy of europe”, for instance on a book from M. Déat, another politica leader from the 40s.