In the ruined city of Fallujah, its pale tan buildings pulverized by Marine artillery in the two great assaults of this long war (the aborted attack of March 2004 and then the bloody, triumphant al-Fajr (The Dawn) campaign of the following November), behind the lines of giant sandbags and concrete T-walls and barbed wire that surrounded the tiny beleaguered American outpost there, I sat in my body armor and Kevlar helmet and thought of George F. Kennan.