You'd have to go further back to the point before Hitler broke so many treaties that his word became worthless. At which point... he's probably too constrained by treaties to do what he did. I wouldn't discount things going different if he'd done everything slower though.

Fall of civilizations podcast suggested the Bronze Age collapse was partially caused by simultaneous volcanic eruption and droughts displacing people and triggering mass warfare in the Mediterranean.

Black skies and failed crops? Time to raze our neighbor's cities out of desperation.