To many, Carl von Clausewitz is known as the Prussian military theorist who, in his seminal work On War, declares the (in)famous words: “War is a mere continuation of policy by other means.” Lacking the necessary contextualization of Clausewitz and his ideas, critics of this well-known line brand him as the “apostle of total war.” At first glance, their reactions seem sensible. They protest the point that war is inevitably the means to gain political ends; why should politicians and policymakers have to resort to violence, when peaceful means of negotiation and channels of diplomacy exist? And better yet, others who fully understand the destructive and capricious nature of war object to Clausewitz’s seeming assumption that war is a handy tool that can easily bring about a certain outcome. Compounded with Clausewitz’s teachings on mass concentration, utmost intensity, and his emphasis on the relationship between political and military objectives in war, Clausewitz’s words here seem especially brutal.
But before correcting critics’ misinterpretations, understanding Clausewitz’s background is key to understanding the teachings and principles found in On War. He was a genuine product of his times. Entering the Prussian military service at age twelve, Clausewitz fought against the French in three different campaigns. At the time, Napoleon was Prussia’s (and the rest of Europe’s) greatest foe. After the devastation of the Thirty Years War, armies fought wars with a limited number of soldiers, and decisive battles were avoided to ensure that not all forces could be lost in a single engagement. The Napoleonic model of warfare changed all of this, introducing the concept of a “nation in arms.” With access to one of the largest populations in Europe and the policy of levée en masse in place, Napoleon sought decisive battles and eventually crippled many European powers with his conquests. It was this experience that ultimately formed Clausewitz’s impressions of war, and the many historical examples found in On War center on Napoleon’s strategies and military insight. Clausewitz’s ultimate argument was that Napoleon could only be defeated if his tactics were adopted by his enemies. So, Clausewitz’s emphasis on military engagements and total destruction of enemy forces is only natural.
What Clausewitz felt he discovered after experiencing the effects of the French Revolution and Napoleonic warfare was the true, uninhibited nature of war. Therefore, On War largely addresses engagements and fighting, without focusing on strategic assessments and preparations of the type one would find at the heart of Chinese militarist Sun Tzu’s The Art of War. For Clausewitz, destruction of enemy forces is the key to victory and the decisive goal to be sought, and the means of achieving this would vary according to the scope of the political objective behind the war. As Clausewitz states, “Since war is not an act of senseless passion but is controlled by its political object, the value of this object must determine the sacrifices to be made for it in magnitude and duration.”
But back to the question at hand. What does Clausewitz’s declaration, “War is a mere continuation of policy by other means,” actually mean in terms of On War itself? As can be implied from above, critics of Clausewitz view this quote as a prescription. War is the only answer to accomplishing political goals, is what such a reading deduces from Clausewitz’s words. But Clausewitz stated this more as a conclusion about the history of war rather than an all-encompassing tactic or rule. He states, “War is no pastime; it is no mere joy in daring and winning, no place for irresponsible enthusiasts…When whole communities go to war—whole peoples, and especially civilized peoples—the reason always lies in some political situation, and the occasion is always due to some political object. War, therefore, is an act of policy.” Here, Clausewitz does not underestimate war and its totalities. Policy, according to Clausewitz, is a combination of rational calculations and choices made to achieve a certain end in politics. But politics, unlike policy, is a chaotic, messy, and uncontrollable construct that often involves extreme emotions. Therefore if the peak of emotions were reached within politics, then rational policy (which would normally use rational means to pursue political ends) would have no alternative but war to achieve the political object. Hence, Clausewitz is not a bloodthirsty warmonger disguised as a philosopher of war. In On War, he simply grounds his ideas of war in reality and experience, to understand the nature of what war is, rather than focusing on a theoretical inquiry on what war ought to be.