Planes existed and bombed things prior to the Maginot Line being built. It was also protected against aerial attack, which is kind of intuitive as the French were familiar with just how much explosives could home from the air after ww1 (though generally by by heavy artillery).

> The Germans went mostly through Low Countries, violating the neutrality of Netherlands and Belgium, not just Ardennes forest.

Would be pretty interesting to see Mexicans reroute to come through canada. I say it in joking, but if you fly to canada and cross over into the US, whats the difference?