the u.s. unleashed its fire power and by december rumsfeld was taking his first trip to afghanistan. >> they've captured a number of al qaeda. they've killed a number of al qaeda. they've wounded a number of al qaeda. >> reporter: the u.s. military looked invincible. until march of 2002, when seven americans were killed in the battle of robert's ridge. one of them, sergeant john chapman can be seen on drone video charging across a snowfield, directly at an al qaeda machine gun position. american troops were tough and brave, but so was the enemy. fighting under the constant threat of being annihilated by airstrikes. as in all wars, it came down to fighting as much for each other as for any cause. army captain will swenson put his wounded sergeant kenneth westbrook on a medivac and gave him a kiss before returning to battle. >> you know, we had a moment we looked at each other.