History is written by the victors, etc. Nobody talks about America's concentration camps, for example, despite the large number that existed around the country, and the large number of "prisoners of war" (read: ex-pat Japs living in 'Merica) they held.
All war is genocidal, in its most stripped-down form. You are seeking to displace another people entirely, either by simply destroying them all, or by subjugating those that it makes no sense to kill.
As for the Atomic Bomb, I find guns to be dishonourable, so you can probably guess what I think about bombs in general.