well the story at the time was some americans and possibly afghans were pinned down at the end of a small valley, from a trench at the tip of the ridge overlooking them and were in an arc of fire, so tillman brought the back up and instead of getting a fire mission climbed the the end of the ridge and assaulted the trenches from there. there was apprently some suspicion that the allied forces in the valley mistook him charging ahead towards the trenches on the ridge as an enemy and shot him. they certainly didnt release much info at the time.