Historian Larry Schweikart argued in his book America's Victories: Why the U.S. Wins Wars, that the surge's success, in part, came from the incredible casualties the US military inflicted on al-Qaeda in Iraq and on the "insurgents" from 2003 to 2006---some 40,000 killed, about 200,000 wounded, 20,000 captured, and nearly 10,000 deserted. He has stated that those levels of attrition on an enemy the estimated size of al-Qaeda were substantial and deeply damaging, not only to the terrorists' efforts in Iraq, but had the effect of depleting them worldwide. Moreover, Schweikart argued, virtually all estimates of enemy casualties were severely under-counted (as are all numbers of guerilla casualties) given the inability to identify bodies which were completely annihilated by explosives or to count carcasses dragged away, as well as how many would die later after attempted medical treatment by other Al Queda sympathizers.