It is up to the politicians to exercise diplomacy, economic sanctions, etc., to achieve the nation's aims, but once those have failed and the nation resorts to arms, it becomes the realm of the generals, and the politicians should leave the war to the professionals.
With few exceptions, students nod favorably and indicate general agreement. Most are career military officers, and their willingness to accept this premise is not too surprising. From their perspective, as operators in the battle space, these words are deceptively alluring. Yet, for those who understand the nature of war beyond the battlefield, this sentence misses the point of war entirely.
Having drawn students in with that "quotation" (which I made up for the purpose), I then provide an effective antidote by introducing them to Clausewitz, the Prussian philosopher of war, and his masterwork.
Projecting a follow-on slide, I show them Clausewitz's most famous dictum: "War is a continuation of politics by other means." In that simple phrase, this staff officer of the Napoleonic era captured the essence of war. The concept has endured for nearly two centuries and gets to the heart of why war exists.
Upon further discussion, the students are weaned from their bridge-window or cockpit or periscope points of view and are able to see that as essential as it is, all of their training in the science of war is merely an element in the accomplishment of some political goal. They see that war is not an end in itself. It is merely a means to an end, no different (though far more dramatic and/or traumatic) from diplomacy or economic sanctions.
Such is the beauty of On War . Although frequently not the easiest reading (much of it was, after all, only a first draft), there are nuggets of pure genius in Clausewitz's treatise. He introduces practical concepts such as "centers of gravity" and the relativity of offense and defense, and he gives practical advice on the importance of war termination as well as warning about over-relying on intelligence.
But perhaps his most enduring value is that he provokes readers to embrace the more philosophical aspects of war.
In most of their endeavors, military people tend to be more scientists than artists or philosophers. But the granddaddy of all our endeavors is war itself, with its major components of strategy, operations, and tactics. And while a substantial amount of science is involved in tactics and operations, strategy is less cooperative.
Take, for example, Clausewitz's "rational calculus of war," where the great war philosopher explains:
Since War is not an act of senseless passion but is controlled by its political object, the value of the object must determine the sacrifices to be made for it in magnitude and also in duration. Once the expenditure of the effort exceeds the value of the political object, the object must be renounced and peace must follow.
This passage might tempt one to treat this "calculus" as a mathematical concept by creating x-y axes with benefits (value of the object) and costs (expenditure of effort) juxtaposed.
But it quickly breaks down in real-world analysis once one attempts to place points in relation to those axes and finds that to do so it becomes necessary to entertain such thoughts as how many quarts of blood a nation's honor is worth.
In the end, such calculations become so subjective that we are forced to subordinate science to more philosophical approaches, ultimately trading in science for art. By reading the philosophical musings of Carl von Clausewitz, we are able to disabuse ourselves of the seductive simplicity of the scientific method. We can open our minds to more subjective approaches to this elusive yet vital thing we call strategy.
This healthy and necessary exercise is more relevant today than even in Clausewitz's time, because it makes the would-be strategist acutely aware of such things as friction and the fog of war.
Such thinking is not a substitute for the scientific approach to military operations. But it can serve as an effective supplement to that pragmatism, broadening the scope of the military mind. Thus it does not fall victim to the rigidity of Germany's Schlieffen Plan—which led to the disastrous trench warfare of World War I—but can place military operations in their proper context. That context is within a strategy that is a means to the desired end.
This, then, is the true value of Clausewitz and explains why the book has been the centerpiece of many a curriculum, and why it continues to be either embraced or challenged by nearly all who attempt to write about strategy and war.