Surely, it is no exaggeration to suggest that the events of the last decade have had a profoundly sobering effect on an American military that, before 11 September 2001, had succumbed to a considerable measure of doctrinal and technological hubris. For that sobering process, several factors were responsible. But the most important contributors have been the unexpectedly prolonged, frustrating, and expensive conflicts in Iraq and Afghanistan.

Americans have encountered this problem before and the response was instructive. In the late 1970s and early 1980s, reacting to a similarly prolonged, frustrating, and expensive war in Vietnam, the U.S. military rediscovered Carl von Clausewitz. The Prussian military theorist's On War had long been a sort of military Rorschach test, with each new generation of disciples interpreting it in its preferred way. In the U.S. military of the 1980s, the Clausewitzian concept that exercised the most powerful attraction was the injunction that military operations should always be directed at an enemy's center of gravity, “the hub of all power and movement, on which everything depends.” That idea seemed to offer a way to escape the militarily and politically painful attrition that had characterized the Vietnam War and, moreover, to mesh nicely with emerging theories suggesting that if one could only employ emerging precision sensor and weapons technologies to detect, target, and destroy certain carefully selected “nodal” enemy capabilities, preferably from a distance, then one might thereby bring future conflicts to a rapid and decisive conclusion.