The trench-warfare stalemate of World War I was the virtually inevitable result of new technology and the cultural mindset of the times. The machine gun had made the battlefield unhabitable in the fifty years since the Civil War: it mowed down soldiers at an inconceivable rate. But the elaboration of defensive entrenchments early in World War I changed all that. An uneasy standoff ensued, an impasse that could not be broken though commanders on both sides sacrificed thousands of men in the attempt. Why could they not see that their efforts were doomed? It is possibly the greatest tragedy of this century that literally hundreds of thousands of men were slaughtered in pointless charges against impregnable machine-gun emplacements. The problem, as Professor Johnson clearly demonstrates, was that senior commanders on both sides simply could not imagine any alternative to the frontal assault. They called it l'offensif a l'outrance, the doctrine of offense at all costs, and they sent men to their deaths like savages sacrificing to the gods of tactical theory. It took a new breed of warrior, the adventurous captains and majors who championed technological innovations like tanks and airplanes, to break through the impasse. The author examines each of the major combatants in the Great War and shows how their cultural institutions perpetuated the grim mentality of attrition. Not by accident, the entry of the United States into the fray coincided with the resumption of the tactics of maneuver that finally led to the Allied victory.