Alfred has (IMHO) hit the nail squarely on the head. This 'war' was lost when it was decided that there was a uniquely military solution to preventing AQ and a host of other loosely affiliated organisations using Afghanistan as a training facility and power base.
Absolutely true, and don't forget, who made those "loosely affiliated organisations" appear to be a single cohesive unit with AQ leading them in the minds of the public? Why, we did of course, even thought it was never, and will never, be true. You can't vote across billions of dollars to fight "brown" people if the great unwashed don't believe there's a big threat out there. Hey, I know, let's keep saying "better to fight them in Afghanistan than on the streets of New York". That way the money keeps flowing, and the average American voter with a room temerature IQ will think it's patriotic to spend all this money - what's a few thousand lives of our youngest and bravest if we keep getting the money right?