@cstross In the Lathe of Heaven the invasion of the space turtles unites humanity against them. That happens in the Harry Turtledove series about the lizard alien colonization too. The lizard invasion happens at the height of WWII, so allies and axis both turn their weapons on the invaders, though it is sort of Spitfires and ME-109s versus F-16's. In a Dalek invasion, I think most of humanity would fight, but some would see advantage in collaborating. Do Daleks every accept human collaborators though? It seems to me that their extermination policy is quite total.