User blog comment:Drgyen/Alien invasion/@comment-422690-20110801190505

The main reason any alien invasion is likely to succeed is b/c we humans can't stop fighting each other long enough to form enough of an alliance to fight back. If humanity has a united front, note that we will be fighting a defensive war against invaders. This means that despite a technology gap, it is entirely possible for us to hold our own, due to the strategic upper hand of fighting defensively. If it succeeds, the only real option is to fight back using guerrilla warfare and scavenging. If we manage to overthrow them, humankind will be left with the civilization equivalency in the BCEs thanks to the rigors of a fight for survival, but with post-modern technology. If aliens conquer humanity and we take Earth back from them, we will likely wipe ourselves out.