I find it difficult that Doombreed can be Hitler. The beast is meant to have been a bloodthirsty warlord, one of the kind that gets to the fight (at least, almost) in the front lines, more in the likes of Gengis or Attila, or some crusader lords...
For me, Gengis was a keen man, not only lost by bloodlust, as were Attila or Tamerlane (I don't even consider Alexander). Simon de Montfort, on the other hand, actually was the kind of man who could become such a beast. Bloodthirsty beyond necessity, brutal, vain and false by nature, a mass murderer... By his own hands. Had he been killed before Muret, the whole history of the world could have changed (easily), saving a lot of bloodshed...
Hitler was a politician (a debased, depraved, degenerated, foolish one) when he sent millions to death. But he was not a warrior. Not the kind of Doombreed.