Quite often that which is considered to be historical fact is altered/upset by recent knowledge. I was reading that if the Germans had had Radar earlier in WW II then the outcome may have been different. In fact they had Radar but didn't realize the potential that was there and even the Americans didn't realize Radar's full potential until the Korean War.

Analyzing historical blunders is always from a position with excellent hindsight. At the beginning of the war, radar was a new, and secret, technology.

The blunders that could have altered the outcome of WWII are plentiful. What amazes me is how many historians have pointed out the problem of having politicians make tactical decisions, such as not invading English and not shifting forces for D-Day, but we still have politicians doing the same thing today.