For nearly two centuries, On War, by Carl Phillip Gottfried von Clausewitz (1780-1831), has been the bible for statesmen and military professionals, strategists, theorists, and historians concerned about armed conflict. The source of the famous aphorism that "war is an extension of politics by other means," it has been widely read and debated. But, as Jon Sumida shows in this daring new look at Clausewitz's magnum opus, its full meaning has eluded most readers-until now. Approaching Clausewitz's classic as if it were an encoded text, Sumida deciphers this cryptic masterwork and offers a more productive way of looking at the sources and evolution of its author's thought. Sumida argues that On War should be viewed as far more complete and coherent than has been supposed. Moreover, he challenges the notion that On War is an attempt to explain the nature of armed conflict through the formulation of abstract theories. Clausewitz's primary concern, Sumida contends, was practical instruction of the military and political leadership of his country. To achieve this end, Clausewitz invented a method of reenacting the psychological difficulties of high command in order to promote the powers of intuition that he believed were essential to effective strategic decision-making. In addition, Sumida argues that Clausewitz's primary strategic proposition is that the defense is a stronger form of war than the offense. This concept, Sumida maintains, must be understood in order to make sense of Clausewitz's positions on absolute and real war, guerrilla warfare, and the relationship of war and policy/politics. Sumida's pathbreaking critique is supported by examination of the Prussian officer's experience during the Napoleonic Wars, previous major theoretical and historical scholarship on Clausewitz and his writing, and modern philosophical and scientific works that have much in common with Clausewitz's creative guide to the consideration of strategic practice. A major study of intellectual and military history, Sumida's book provides a provocative and above all readily comprehensible treatment of a previously inaccessible classic. It will surely become essential reading for all military professionals and serious students of military thought.