Air University Review, May-June 1980

Clausewitzian Lessons for Modern Strategists

Dr. Thomas H. Etzold

CARL VON CLAUSEWITZ believed, as Peter Paret has noted approvingly, that theory, whether of art or of war, should promote the understanding of history. For Clausewitz, personal experience and a deep understanding of history constituted the essential catalysts for the alchemy in which high intellect might be transmuted into good judgment. Such judgment, he thought, was a vital quality of military and professional leaders, and thus the desired result or product of education.1 This view invites inquiry as to whether Clausewitz's own theoretical excursions meet his test, that is, assist in understanding history in ways that refine judgment in political-military matters. Does the theory of war as elaborated by Clausewitz help, for instance, to understand the wars of Napoleon and, if it does, in what ways? Does the Clausewitzian theory of war illuminate the history of warfare through the ages in a manner that proffers lessons to contemporary strategists and, if so, what might they be?

The answer to each of these questions is clearly yes. This answer derives from the implications, for both questions, of a single proposition, namely, that Clausewitz's explication of the nature and dynamics of war accounts for the problems, not to say the fate, of winners and losers in war-Napoleon at his zenith and Napoleon at his nadir. The validity of Clausewitzian observations in analyzing the difficulties of winners and losers in war forms one of the most important reasons for the universal utility of Clausewitzian analysis in studying the history of war and thus for the contemporary significance of Clausewitzian theories and teachings.

This argument, one hastens to add, springs from no presumption that we, or perhaps anybody, could provide either conclusive arguments or inclusive answers to questions of such scope. Commentators on Clausewitz remark on the depth and breadth of his intellect, the immensity of his achievement. And it is the fate of such commentators to experience the humbling intellectual anguish flowing from the realization that one is in a sense overmatched, that it is virtually impossible to deal thoroughly in any brief compass with any of the more important elements of Clausewitzian theory and logic, save at the risk of oversimplification to the point of triviality. Yet Bernard Brodie's melancholy observation holds true: for students of war--whether the wars of the present and future or those of the past--there is no substitute. "Clausewitz's work stands out among those very few older books which have presented profound and original insights that have not been adequately absorbed in later literature. "2

Clausewitz's teachings concerning the nature and dynamics of war may, perhaps, best be approached through recollection and elaboration of the most familiar of his words, the dictum that "war is nothing but the continuation of policy with other means."3 Once little the dictum that "war is nothing but the continuation of policy with other means."3 Once little understood, this observation now perhaps is too easily grasped. The efforts of contemporary commentators and war college faculties to impress scholars and soldiers with the simple logic of the Clausewitzian statement have, if anything, succeeded too well. That, even in political-military affairs and war, ends should dominate means, purposes govern operations, seem so true as to be self-evident, so unremarkable as to excuse even the eager student from further rumination. Brodie tells of a retired British officer of very high rank remarking that he had once tried reading Clausewitz but had got nothing out of it. "If he had encountered strange new ideas requiring some effort to comprehend them . . . he might well have made that effort and perhaps carried away a feeling of being suitably rewarded. Instead he encountered wisdom, and thought it was nothing new."4 It is worth wondering whether current commentators and courses do more to convey a sense of the wisdom to be found in studying Clausewitz or a sense of the self-apparent.

For this very reason, Paret's recent juxtaposition of Clausewitz's writing on the theory of war with his treatment of the theory of war seems timely and instructive. In discussing the theory of art and by extension the interplay between theory and reality in general, Clausewitz affirmed the central significance of the ends-means relationship. Rules of theory, he wrote, "are not intended for individual cases, and action in the individual case can be determined only by [applying the concepts of] purpose and means. "5 But as Clausewitz noted repeatedly in his writings and especially in On War, this was easier said than done. "Everything in war is very simple, but the simplest thing is difficult . . . . but the difficulty is not that erudition and great talent are needed . . . there is no great art to devising a good plan of operations. The entire difficulty lies in this: To remain faithful in action to the principles we have laid down for ourselves."6

Why such difficulties should intervene between plan and action Clausewitz explained with his well-known and indeed fundamental contribution to the theory of war, the concept of friction, In Clausewitz's definition, friction encompassed the host of elements--chance, uncertainty, effort, weather, and other psychological and material factors--that always cause the experience of war to diverge from the expectation of it.7

The concept of friction, the centerpiece of Clausewitzian theory, also provides a key to extending ends-means considerations into useful conjunction with other important constituents of Clausewitzian theory. Several such components, in spite of their relative obscurity, hold great instructive value for historians and contemporary strategists seeking to understand war's consequences for winners as well as losers, in past as well as future wars.

In treating ends and means in strategy and war, Clausewitz implied as a matter both of logic and psychology a certain proportionality between the scale of effort, cost, and risk a state would reasonably accept on one hand and the value of objectives in contention on the other. One important reason for the distinction Clausewitz drew between war for limited aims and war for unlimited aims related to this exact point. It was sensible to think that states warring for concession would show less inclination to approach the extremes of violence and to exert themselves to the point of exhaustion than would states warring for the overthrow or extirpation one of the other.8

I n real war, however, and in large part because of the workings of friction, the tidy rationality of proportion between means and ends always breaks down. Moreover, both winners and losers in war, those whose fortunes rise and those whose fortunes decline, suffer from this fact. For the contender who meets initial successes in war, the ease of attaining them and the relative advantages accruing from them encourage the expansion of war aims, the enlargement of expectations. Correspondingly, there is likely to be a willingness to scale up the level of effort from that originally envisioned. For the contender who meets with reverses early in war, there is the unpalatable choice between accepting an unsatisfactory outcome, which is tantamount to forsaking the political aims that led it to accept or initiate war in the first place, or increasing its exertions and accepting greater risks so as to vindicate earlier decisions for war and continue the pursuit of advantage in war. Usually, in this latter situation, there will also be an inclination to enlarge war aims so as to compensate ultimately for the costs of early setbacks and to offset or otherwise redeem the greater-than-expected costs, exertions, and sacrifices of the war.

For both winners and losers in war, the breakdown of the ends-means or policy-strategy relationship is a virtual certainty. What is more, that breakdown will probably lead in both cases to an enlargement of the scale of effort and ambition in war.

Here war's momentum sets in, the tendency of war toward the absolute. It is perhaps not sufficiently appreciated how much Clausewitz worried about war's terrible tendency toward uncontrollability. He warned not simply that war would tend to the extremes of violence, although he realized that to be true. In this most gloomy conclusion, he warned that war once begun becomes progressively less manageable, less controllable, less susceptible to direction.9

What goes wrong? War, in a Clausewitzian sense, causes a nearly universal problem: once it commences, battlefield successes and battlefield frustrations alike cause the aims of the contenders to seem inadequate, unattainable, or perhaps simply mistaken. As indicated, in these circumstances aims usually grow. The enlargement of aims forces an increased war effort; or the need for an increased effort, whether to avoid ruin or consolidate gains, causes a corresponding enlargement of aims. The means ends relationship in either case becomes unstable; means and ends begin to act on each other in what one might describe as- a reciprocating fashion, each causing the other to swell in a form of escalation all too familiar to Vietnam-era Americans. This reciprocating action with its built-in escalatory dynamic constitutes war's momentum, its tendency to approach the extremes of violence and to run out of control as the aims of contenders devolve into flux or even chaos.

It might seem that, when the aims of contenders in war become obscure or seem unattainable, whether because of successes or reverses, statesmen and generals should simply seek negotiated peace. But political leaders, and for that matter military leaders, can rarely if ever ignore sunk costs. They get neither tax credit nor political credit for their losses, nor can they usually defer the consequences of gain or loss to moments of greater advantage or lesser liability.

In the Clausewitzian formula that war tends toward the absolute, then, one finds a profound caution on the resort to violence for political purposes. Clausewitz means that wars tend to run out of control. Further, he suggests that this sobering dynamic worsens with the passage of time and with the intensity of violence in any given war. Finally, and of utmost importance, he teaches that war's controllability decreases as the scale of effort and objectives increases.10

Hence his qualitative distinction between war for concession, that is, limited aims, and war for overthrow, or unlimited aims. In Clausewitzian terms, war for unlimited aims carries a qualitatively distinct risk relating to the tendency of war to run out of control and approach the extremes of violence. Here lies the significance of Paret's profound observation that the ethical postulates of Clausewitz's views on the workings of state power "in practical terms stood for limited aims in foreign affairs."11

When war tends to the absolute, it reverses the Clausewitzian ideal. Instead of the controlling dominance of purpose, of objectives, there are (in modern Defense Department parlance) capabilities in search of missions; there is opportunism both political and military and, in war, operation for operation's sake. Strategy comes to dominate policy; means become ends. War begun as a continuation of policy ends by destroying the policies and leaders responsible for the war in the first place. There may seem to be a certain rough justice in this; there is an even more certain catastrophe.

To RETURN to the questions posed at the outset in this essay, does the theory of war according to Clausewitz help in the understanding of the wars of Napoleon? Yes, for it recalls to the student of those great campaigns some sober truths too readily obscured or discarded in the collective haste to apotheosize genius. Even such a man as Napoleon must be considered the subject, not the master, of the forces moving through his times, not least those of the nature and dynamics of war. Men are usually victims of their times, rarely in command of their institutions and circumstances, never of their destinies. Napoleon's genius lay in his grasp of the techniques of war, the political weaknesses of his adversaries at home and abroad, and the potential of the military instruments and institutions created by the Republic. His failures were in large measure the result not merely of character defects-immodest ambition, egoism, and perhaps irrationality--but of the workings of war's dynamic on his situation as on that of his less brilliant contemporaries and foes.

From 1808 onward, Napoleon suffered repeatedly from disruptions of his calculations concerning the ratios of resources and efforts required to attain his purposes. His efforts to drive England to terms via a combination of economic warfare and continental military successes foundered again and again. The reciprocating instability of Napoleon's ends-means reckonings showed in examples as modest as his administrative modifications of the continental system, when he proved unable to suppress smuggling, and in examples as grand as the debilitating Peninsular War and the calamitous invasion of Russia. Indeed, fluctuations in focus and endeavor in Napoleon's latter years as emperor present such complexity that scholars still debate whether he really had any established goals and, if so, what they might have been.

To have no clear-cut objectives is, in the Clausewitzian view of war, undesirable to be sure. But it is unremarkable as well, for it is the most likely condition of nations and their leaders after many years of war. War tends to become unmanageable, to disrupt policy and force alteration of purpose, and thus to destroy all reasonable limits derived from the governance of ends over means: these things explain as much about the course and outcome of Napoleon's wars as any amount of political or psychological analysis.

Does Clausewitzian theory clarify aspects of the general history of war and so instruct contemporary strategists? Again, yes, for strategic planners consistently overestimate the power of men to shape their times and their problems. It is commonplace among military professionals to believe that proper planning will shield armies and nations from the potentially disastrous effects of war's dynamics or at least mitigate them in ways that bear on the likelihood of success or failure in war. Modern military management fosters the belief that, by some combination of probabilistic mathematics and innovative personnel policies, planners and commanders can make war accord with plans, suppressing the effects of chance and uncertainty in the military sphere.

Clausewitz teaches, nevertheless, that wars do not go forward as planned, that friction and war's momentum will unavoidably come into play. Together these forces will ensure that the experiences of war for all those engaged will depart in significant measure from their expectations. In turn, this divergence of real war from war on paper will disturb the delicate relationship of effort to objectives, both for those doing relatively well and for those doing relatively less well. An understanding of Clausewitz's theory of war requires strategic planners to avoid, at all costs, the temptation to exaggerate the correlation between military effort and political results. The idea that the resort to violence can be in any sense surgical or precise is one of the most mistaken and dangerous propositions of our own times. For in Clausewitzian terms, war in practice is an extremely imprecise and erratic instrument of statecraft. Understood in this sense, Clausewitz's writing on war forms the most closely reasoned and sustained argument against the use of war for political purposes to be found in the entire literature on war and strategy.

In an overridingly important sense, war brings the same consequences to both winners and losers. Knowing the theory of war does not exempt one from the effects of friction or from war's tendency toward uncontrollability. Both winners and losers must accept that the resort to war will set in motion forces that neither can control. War will bring to winners as well as losers results that are at once unintended, unexpected, and for the most part unwanted. In Correlli Barnett's eloquent words concerning World War I, "War is the great auditor of institutions."12 He might have added that institutions and leaders more often fail than withstand war's severe tests.

Thus, the task of today's planners, generals, and statesmen, as of those in the past, is not to make war conform to plans but to make plans in conformance with war's certain nature and dynamics. These they must learn in the study of history. Together, the Clausewitzian theory of war and sustained historical study compose an intellectual regimen vital to the political and military leaders of our time. This demanding study reinforces the moral virtue of prudence, often said to be essential in statecraft and surely of equal significance in strategy. It may also contribute to a healthful lowering of expectations in politics and, more especially, in war. For generals and statesmen will always have to struggle to remember that they are more the servants of fate, the agents of' fortune, than their captains and kings.

Naval War College
Newport, Rhode Island

This article was originally prepared for the Tenth Consortium on Revolutionary Europe (1750-1850), which met at Florida State University, Tallahassee, on 6-8 March 1980. It appears here by special permission from the Consortium.



1. Peter Paret, "The Genesis of On War," in Carl von Clausewitz, On War, edited and translated by Michael Howard and Peter Paret (Princeton, New Jersey: Princeton University Press, 1976), pp. 3-25, esp. pp. 8, 11, 12, 14, 15, 23. See also Clausewitz’s own discussion on pp. 140-42, 146, 147, 156-76. (All pages references, unless otherwise noted, are to the Howard-Paret edition of On War.)

2. "The Continuing Relevance of On War," in Howard and Paret, Carl von Clausewitz, On War, p. 50.

3. Clausewitz, On War, pp. 69, 86, 87, 605-10.

4. Howard and Paret, Carl von Clausewitz, On War, p. 45.

5. Ibid., pp. 14, 15.

6. On War, p. 119; Paret, "The Genesis of On War," p. 17.

7. Paret, "The Genesis of On War," pp. 17, 18; On War, pp. 100-26.

8. Paret, "The Genesis of On War," p. 21; On War, pp. 91, 92, 579-610.

9. On War, pp. 75, 76, 77, 87, 88.

10. Ibid., pp. 582-94, 603-10.

11. Ibid., pp. 90-99, 585, 586; Paret, "Clausewitz and the Nineteenth Century," in Michael Howard, editor, The Theory and Practice of War (New York: Frederick A. Praegar, Inc., 1966), p. 38.

12. Correlli Barnett, The Swordbearers: Supreme Command in the First World War (New York: William Morrow and Company, 1964), p. xvi.


Thomas H. Etzold (Ph.D., Yale University) is Professor of Strategy at the United States Naval War College, Newport, Rhode Island. He is the author of The Conduct of American Foreign Relations: The Other Side of Diplomacy as well as coauthor and editor of Aspects of Sino-American Relations since 1784. He has written many articles for professional historical and military periodicals concerning American defense and diplomacy. Dr. Etzold is a previous contributor to the Review.


The conclusions and opinions expressed in this document are those of the author cultivated in the freedom of expression, academic environment of Air University. They do not reflect the official position of the U.S. Government, Department of Defense, the United States Air Force or the Air University.

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