[quote=@Space Communist]
Hm...what about a pan-American movement in the US, Canada, and Mexico, instead of the US alone? That would increase the number of natives fighting for independence tenfold. Not only that, but it would provide some relief on the US for a while as the fighting becomes concentrated in Canada and Mexico (though the war would inevitably reach Cascadian territory and the Western US).

As for the Balkans, my mistake. I didn't know Serbia had taken control of those countries. Still, a union of some sort does not seem out of the question.

Also, wasn't Croatia annexed by Austria?
[/quote]

Still not nearly enough natives. And the US and Canada detests each other. And Mexico is aligned to the Third International and ideologically split from the US and Canada. So a union in North America isn't possible, let alone a union of the native tribes.