I've just finished a remarkable book called The Good Soldiers, by David Finkel. It is the best grunt's-eye view of the war in Iraq that I've read; certainly, it's the best written. But it also raises, implicitly, the mystery of our qualified success there. Finkel follows an Army battalion through the 2007 surge, as it attempts to secure a particularly nasty and neglected area of Baghdad. This was the first attempt to implement the Army's new counterinsurgency doctrine, and the troops have their doubts about the new tactics. Major Brent Cummings, the second-in-command, reads the doctrine and is perplexed by sentences like "Sometimes, the more force is used, the less effective it is." Cummings is an infantryman. He has been trained to "close with and destroy the enemy." This new form...