well... America didn't lose the Vietnam war because their support back home wasn't strong enough. They lost the war because of geographical ignorance and the feeling of superiority. They were not prepared for that region... a place where superior tech counts for nothing. This is a lesson not learned for the Afg war as well.

Anyways, back to the Manhattan Project. It's not fair to say that German scientists emigrated to America to work on the bomb since the chief catalyst for the theoretical physics behind it all, Einstein, was not invited to the party. So far as I can find, Klaus Fuchs was the only German (there may be more) but ahead of him was Oppenheimer, David Bohm, Leo Szilard, Niels Bohr... none German. Maybe Einstein wasn't invited because he opposed the theory of quantum mechanics.