At the center of Baghdad's neglected North Gate War Cemetery, near the edge of the old city walls, stands an imposing grave. Sheltered from the weather by a grandiose red sandstone cupola, it is the final resting place of a man from whom George W. Bush could have learned a great deal about the perils of intervening in Iraq.

Lt. Gen. Sir Frederick Stanley Maude was head of the British army in Mesopotamia when he marched into Baghdad on a hot, dusty day in March 1917...