Dunkirk or “operation Dynamo” as it was called was not a British defeat, but could have been. The German air superiority cost them 177 planes to about 130 british planes lost and while the France were of course losing every where else Churchill got in total some 338,226 troops were evacuated (220,000 British, 120,000 French), while the germans got 34,000 british soldiers captured plus all the British equipment and of course some additional French soldiers.
In the matter of “Overlord” to say this:
It should be pointed out that Hitler never gave complete operational control to any of his generals if he could help it…. comes from being a paranoid megalomaniac. If we are going to talk about changing Hitlers personality we may as well consider that the war never happened.
Means that any speculative analysis of any Historical point according to your interpretation History has no real value because nothing could have happened any other way than it did, because after all people act exactly consistent at all times and could not possibly make decisions contrary to their personality.
Does this mean we cant learn from it?
Rommel in complete command of OB West would have meant pushing the Allies in the sea on the first day, way before a beachhead would be possible. Quite possibly all the small factors of Hitlers poor sleeping habits,Rommels wifes B-day, military exercising planned for the following day and Eisenhowers decision to cross the channel on the 6th all contributed to its outcome, along with “hitlers personality”.