OK. WWII time!! ;D
There have been a million (or so) post mortems and examinations of all the 'what ifs' and the 'maybes' regarding what Hitler did and did not do. Most people agree that one mistake or another led to his inevitable downfall.
I don't know, and I don't believe any of us ever will, whether the Reich could have lasted any significant period longer than it did, even if Hitler had not made the 'glaring' errors and misjudgements that he did.
However, I feel, apart from the fact that he may well have defeated the RAF if he had not turned to bombing citiies when he did. Apart from whether the Japanese had stayed away long enough for England to be brought down before the US became involved. There is one aspect that may have made a significant difference, at least to the length of the Reich's exisistence. ???
I'm talking about the hypothetical success of the Invasion of Russia.
What would have been the Reichs position, strategically and politically, if they had attacked earlier (or later) and actually swept across 'Russia proper', before the winter set in, and of course, if they had had a reasonable 'supply' line option organised?? ;D
A situation where the Reich would not have had the 'Second' and very 'resource draining" front. Instead just a need for a reasonable sized occupaton force (and the inevitable SS and Gestapo operations). ???