It's a history book first and foremost, that's how it feels to me. How did we get HERE under the dominion of THIS Empire.
One of the themes of the book I think, is that the goodies didn't win WW2. This is a commonplace of the paranoid set and for some it leads inexorably to anti semitism and Hitler worship. But it's not the same as saying the Nazis were right or that the world would be a better place had they of won but in locating the commonality and the blurring of identity between the two sides, both representing a specific vision of modernity. That they created the future in collaboration almost, hand in hand.