Episode 3.19: Jane Doe
I've seen this episode before (several years ago), and IMHO, it's one of the most interesting 3rd season eps because of the what-if questions it poses.
I don't know if killing Hitler would have stopped WW2, but I can see why even LaCroix regretted not doing it. I can only imagine how reality would be much different. Or perhaps, if LaCroix had brought Hitler across, would there have been a WW2 or worse? If he had, do you think LC or the enforcers would have been forced to destroy Hitler anyway because of his violent tendencies?