"but nothing in this life is certain. What you are failing to allow for is unforeseen circumstances. There is nothing wrong with that. None of us can because they are, well, unforeseen."

Unforeseen circumstances are real time, they do not exist in retrospect which is why 20x20 hindsight is so perfect.

The "unforeseen" circumstance in 1938 was that Britain and France with the help of Italy were prepared to negotiate and come to an agreement - It meant sacrificing Czechoslovakia.

Hitler got the tanks he needed to invade and conquer Holland, Belgium and France.

The "unforeseen" circumstance in 1940 was the effectiveness of Great Britain's integrated air defence system which allowed ~700 fighters to effectively deny air superiority to, and defeat, three German "Air Fleets" of 3,500 aircraft.

The "unforeseen" circumstance was the use in the Spring of 1940 of 100 Octane fuel that boosted the performance of both the Spitfire and the Hurricane so that both could successfully take on any German fighter (Using the same fuel in a Gladiator would not have done the same job)

To try, in retrospect to suggest "unforeseen" circumstances that could have effected the outcome of the German onslaught in the West is ridiculous.