A year ago, Conrad Crane got a call from an old college classmate—Gen. David Petraeus, an Army three-star who had fought in Iraq and now wanted help drafting a new counterinsurgency manual for the military. Crane, who heads the military-history department at the Army War College, began by listing the paradoxes American troops face in Iraq.

"Some of the best weapons for counterinsurgency do not shoot," he wrote, emphasizing the need, above all, to win over the local population with aid and reconstruction. When the 279-page manual was published last week, it helped solidify Crane's position as one of the more innovative thinkers in his field. Is it too late to be useful in Iraq? "I hope not, but it's broader than that," he says. "If we'd have written a manual that's only good for Iraq, we'd have failed in our mission."