In harry turtledoves world war series, Earth is invaded during wwII by aliens with near future tech. Everyone forms uneasy alliances (even the communist chinks, the capitalist chinks and the fascist japs), and the soviets and the nazis and the brits to fight the greater common enemy.
In the end, europe is under germany's third riechs control, britian is reduced to just the united kingdom, the soviets develop the bomb and manage to stay as the soviets, the americans remain the americans, and the japs actually gain quite a bit of territory,
Oh and the only other free nation is canada.
The rest of the world (the third world) is pretty much taken over by aliens who are forced into a treaty.
eventually humans surpass the aliens tech wise and learn FTL travel before the aliens do, (the aliens using cryogenics and sub light drives) They use the ftl travel to send a space ship to the aliens home planet with nukes for some reason. i dunno, i never finished the last book, it stopped being about lol nazis vs aliens, and started being about politics and colonization politics. got boring real fast.