Your power is your money, to the extent it isn't diluted away. But that is taken by force and you're handed a multiple choice questionairre in its place. I am assuming you are talking about world war 2, because there is not even a good excuse for every war since.

And for WW2, even if the propaganda is true (not close), consider the possibility all the American soldiers died in vain, in a war against an enemy already defeated by the Russian winter.