On War is two centuries old, its author admitting that it is unfinished. It is a difficult book to read. Some sections are long and detailed, others are concise summaries, and yet others have the look of notes to be expanded.
Being two centuries old, On War treats the war of the early eighteenth century and the technologies then in use. We’ve come a long way since then: no more carefully formed-up marches into cannon fire. No more elaborate uniforms for battle. We can see through the dark of night and launch missiles that find their targets largely on their own.
Clausewitz’s logic is not fully worked out. His detailed exegeses of defense and attack in books six and seven can stand on their own, but their connection to his generalizations are sketchy. (Although I suspect, as another commentator concluded, that his generalizations would not have been possible without his exhaustive considerations of attack and defense.) Most importantly, he states that his central principle is
War is the continuation of policy with other means.
but he neither shows how it follows from the rest of the book nor gives much of an explanation of how to apply it.
So we might be justified in jettisoning this period piece as a curiosity of its times. But it is considered a classic and is taught to young soldiers. Translations are regularly refreshed. There must be reasons for this.
A surprising number of Clausewitz’s specific observations of tactics still hold. It can even be argued that he anticipated guerrilla insurgencies, which we tend to believe are very modern phenomena. Other examples have been cited by others in the symposium; this is not my area of expertise.
Some aspects of war, of course, are timeless. It’s possible that among our not-quite-human ancestors, some stood out in group conflicts as having coup d’oeil, although they certainly didn’t call it that. And some of those aspects are not confined to war. Did the leaders of the first bands to move northeast out of Africa have the coup d’oeil to recognize that a new start was needed, whether because of conflicts with other groups or resource exhaustion or a need to do a new thing? And we are familiar with Clausewitz’s friction, which besets all attempts to make something happen.
Clausewitz himself said that the book is not prescriptive, that war cannot be solved as a mathematical equation. This is, in itself, an important generalization, observation and prescription about war. War has its own logic, he says, and it will get away from the policy-makers who believe they can use it to reach their ends. It will even get away from the professional military and collapse into savagery if they are not careful.
Such a mixed bag. How, then, shall we read On War?
On War is a book to argue with, to test its observations and generalizations against our situation and vice versa. It is not a guidebook (as Clausewitz is careful to say), but a checklist, but certainly not a checklist of the kind that pilots use before cranking up the engine.
Clausewitz argues with himself, and, especially given the differences between his time and ours, would expect nothing less from us. His own internal arguments and statements of limitation themselves are clues to what we need to ask. How much of what he has to say is still relevant? Under what circumstances might that work? If statesmen and generals ignore his advice, what does that indicate? What is victory and what is tactical success?
Clausewitz developed the major themes of war and found many nuggets of wisdom along the way. War is a complex enough human endeavor that none of that wisdom applies everywhere, at all times, but, because war is a human endeavor, much of that wisdom can also be applied elsewhere, with the same arguments and questions to work through.
This symposium has provided some of that discussion. There is no end to the discussion, and every reader will find different things in the book at different times.