Strategic Perspectives: Clausewitz, Sun-tzu And Thucydides – Analysis


Strategy should be thought of, metaphorically, as the bridge connecting military power with political purpose. It is best defined as the use that is made of force and the threat of force to achieve policy ends.i This definition privileges military strategy, which is the focus of this article. However, the importance of the “grand strategy” should also recognize what Americans call national security strategy. The latter can be defined as the coordinated use of all the assets available to a polity or other security community to achieve policy outcomes.ii

Whether one’s focus is narrowly military or is much broader, the distinguishing quality of strategy is its instrumentality. Strategy is not military power per se, nor is it the actual application of that power. Similarly, strategy is not policy. These may seem to be statements of the blindingly obvious, but misunderstanding of the nature and function of strategy is, and has always been, widespread.iii This intellectual failure can have dire practical consequences. After all, we are talking about nothing less than war, peace, and even survival. A belligerent that “does not really do strategy,” for example, Germany in the two world wars, will, that is certain, pay a horrendous price for this lack.

Strategy matters. Indeed, historically viewed, given the sad centrality of war to the course of world events, there are few ideas and behaviors that matter more than strategy.

What Strategy Does

Strategy provides a theory of success. It is the source of operational plans intended to convert nominal military capability into useful performance against the enemy. As theory and as plan strategy explains how victory, or at least advantage, will be achieved. Such is its function and purpose. The metaphor of the ‘strategy bridge’ already introduced is especially apt, because it suggests both the possible fragility of the connection between military power and policy and the importance of two-way traffic between the two “banks.”

In essence, strategy performs a conversion function. It converts an army into a tool of statecraft directed to achieve desired political results. Little reflection is required to recognize the difficulty of this task. The strategist must convert one currency into another; military power into political benefit. This is simple to explain, but hideously challenging to do successfully and concretely. The task is relatively easy if the political object of a war is the total defeat of the enemy. In that rare case, the annihilation of the foe’s ability or will to resist is the object of both political and military activity. But even in such an elementary case, the strategist should be concerned to win the war in such a way that the postwar political context is not fatally compromised. More often than not, however, the dominant political goal in a war falls far short of achieving a total victory. The strategist seeks to use military power merely only in order to convince the enemy that he needs to make peace, lest worst consequences befall him. In that much more common situation, strategy becomes a matter of ever-debatable judgment. How much damage, and of what kind, will be necessary to reshape the political will of the adversary? Rephrased: at what point of military and other disadvantage will he cry quit?

To illustrate the nature and function of strategy, consider the behavior of Winston Churchill’s British government in the summer of 1940. With its army (the BEF: British Expeditionary Force) bundled off the continent in late May and very early June (evacuation from Dunkirk, May 26-June 4), and its French ally suing for a humiliating armistice on June 22, Britain’s previous plans were rendered invalid. In short, its former strategy had been destroyed by events. The enemy intervened, as Germany had a malign habit of doing.

Even fine strategic minds can be guilty of forgetting temporarily the all important truth that “[w]ar is nothing but a duel on a larger scale.”iv Britain and France had agreed on a strategy of choking Nazi Germany to death in a long conflict in which the large resources advantage of the allies would prove decisive, as they had in 1918. Unfortunately, Germany declined to let itself be out-resourced in a long war, and instead defeated France in a short war that lasted only six weeks.

Britain could have sued for peace in July 1940. Indeed, that appeared to be the rational next step, since London could devise no plausible theory for how it would achieve victory, and therefore no credible strategy to bring about such a happy outcome. So, what was the British strategy in the truly desperate context of mid-1940? Churchill, with huge popular backing, insisted upon continuing the war. His strategy consisted of the following elements: (1) deny Germany the option of conducting a successful invasion (meaning that the Royal Air Force [RAF] must remain competitive, and the Royal Navy [RN] must stay dominant in home water); (2) remain militarily active, though not necessarily effective, both for the sake of domestic and imperial morale, and – above all else – to tell the Americans that Britain was still fighting; and (3) be patient and wait for something decisively advantageous to turn up.

To be specific, British strategy in 1940–41 amounted to a determination to remain undefeated pending the anticipated entry of the United States into the war. That long predicted event was nowhere in sight in 1940, or through much of 1941, but Churchill needed his public and his political colleagues to believe that it was a certainty, sooner rather than later.

One might add a fourth element to these three items in British strategy. Churchill nursed the hope – perhaps the conviction – that simply by holding out, against severe odds, Britain would give Adolf Hitler time to make a fatal error or two. In point of fact, the Fuhrer made two such errors: he invaded the Soviet Union on June 22, 1941, and quite gratuitously declared war on the United States on December 11 of that same year.

In the historical example just provided, Britain employed its overmatched (except for the RN, and the RAF over England) military forces with great strategic skill. Ineffective bombing raids were conducted – ineffective, that is, militarily. But RAF Bomber Command, although a paltry tool militarily, was used as a strategic instrument which carried a political message. Similarly, Churchill, ever the romantic warrior, demanded that the British armed forces carry the fight to the enemy in any way that they could. In addition to the bombing campaign, commando raids on the very long German-held coast of Europe were sanctioned.

Also, an organization designed to foster and support insurgency against German occupations on the continent (the Special Operations Executive, or SOE) was created. And, of course, the British could cheer themselves up and secure favorable headlines around the world by beating the Italians in the desert in North Africa and by conducting various and successful daring operations. Moreover, it was most kind and obliging of Mussolini to provide Britain with an enemy it could defeat in 1940.

The point of this article is to illustrate in a historically concrete manner the nature and function of strategy. In World War II Britain turned in a decidedly superior strategic performance. Despite the military disasters of 1940 and 1941, Britain functioned strategically to great political outcome. Britain’s strategic performance contrasted in the sharpest way with that of Germany. To cite a point made earlier, Germany did not really “do strategy.”v

When the Schlieffen-Moltke Plan of 1914 for victory over France in six weeks failed, Germany had no “Plan B”: it had no strategy worthy of the name. The Great German General Staff carried out operations, not The German conception of waging war rested on the overconfident assumption that by the execution of a brilliant operational concept the enemy would cave in and be defeated in a short war. When that concept proved faulty, as in 1914, the Germans were strategically baffled and at a loss of what to do. As if 1914–18 did not provide lessons hard enough, Germany made the same mistake of neglecting its strategy in the return to the battlefield of World War II. When Operation Barbarossa, the invasion of the USSR, failed to deliver victory in three months, as had been expected, again the Germans were strategically bewildered and confounded.vii

Prussian-Germany, the country that provided us with “the only truly great book on war” and strategy that has ever been written, as American strategic thinker Bernard Brodie wrote of Carl von Clausewitz’s classic,viii On War, demonstrated twice in thirty-one years exactly why strategy is important. The most admired Prussian-German soldier of the late nineteenth century, Field Marshal Helmuth Graf von Moltke, the victor of the wars against Austria in 1866 and France in 1867–71, praised Clausewitz even as he resolutely misunderstood him. Moltke, the true father of the mature General Staff system, set the German Army firmly on the path of tactical and operational excellence, although at the expense of strategy. In his own revealing words:

“In fact, strategy affords tactics the means for fighting and the probability of winning by the direction of armies and their meeting at the place of combat. On the other hand, strategy appropriates the success of every engagement and builds upon it: The demands of strategy grow silent in the face of tactical victory and adapt themselves to the newly created situation. Strategy is a system of expedients.”ix

Whereas the Germans were plainly guilty of ignoring strategy in the two world wars, Americans have been known to adopt the wrong strategy. One must hasten to add that faulty strategic choice is not, of course, a uniquely American malady. Vietnam offers a clear historical example of what happens when a powerful commanding general (William C. Westmoreland), functioning according to the dictates of his organizational culture, persists in pursuing a strategy that does not work. One need hardly comment that it is important not only to have a strategy, which is to say to function strategically, but also to have a strategy that is sound or, at least, is sound enough.

Strategy is generally deemed a good thing, even if its nature and purpose are not well understood. In Vietnam from 1965 to 1968 America did not lack a strategy. General Westmoreland, no doubt an excellent general for the conduct of conventional warfare against a regular enemy, was devoted unshakably to a strategy of a war of military attrition. He had two broad options to choose from: He could either employ U.S. forces to try to seek out and destroy the Vietcong or adopt a form of enclave strategy designed to protect the bulk of the population.

He chose the former, despite a substantial body of expert advice as well as actual contemporary experience which recommended direct engagement. The result was that the people of South Vietnam were typically left perilously under protected while the American army engaged in largely futile sweeps, search and destroy missions of the more remote regions and jungles of the country for an evasive enemy.x

So it is essential to have a strategy but scarcely less important to have one which can succeed. By its very nature strategy is a practical activity. The most distinguished American strategist of the twentieth century, Bernard Brodie, is unambiguous in his characterization of his profession:

“Strategic thinking, or “theory” if one prefers, is nothing if not pragmatic. Strategy is a “how to do it” study, a guide to accomplishing something and doing it efficiently. As in many other branches of politics, the question that matters in strategy is: Will the idea work? More important, will it be likely to work under the special circumstances under which it will next be tested? …Above all, strategic theory is a theory for action.”xi

Given the importance of strategy, the vital character of its role and the often truly awful consequences of erroneous strategic choice, what help is available to us from the great thinkers of the past?

Assistance from the Classics

Carl von Clausewitz
Carl von Clausewitz

Books on military topics are perennially popular, as also are works on the wisdom or otherwise of the use of force today. But books on the general theory of strategy, studies that have meaning for all places, purposes, technologies and times, are exceedingly rare. In point of fact, the past 2,400 years has yielded only three classic works on this subject and, arguably, no more than five others of enduring value. That is not a rich haul of profound collected reflection from the sad abundance of collective strategic history.xii

The three classic works on strategic theory differ about as much as can be in all aspects of their provenance. Where they agree, by and large, are in the ideas that they present. The books in question are:

  • Carl von Clausewitz, On War (written in the 1820s, published unfinished in 1832 after the author’s death in 1831).
  • Sun-tzu, The Art of War (written ca. 400 BC in China in the period of “Warring States, 403–221 BC”).xiii
  • Thucydides, The Peloponnesian War (written ca. 400 BC by a somewhat disgraced Athenian general: the History stops at 411, rather than proceeding to the final defeat of Athens in 406).xiv

In addition to these three masterpieces, five other works merit honorable mention:

  • Antoine Henri de Jomini, The Art of War (1838).xv
  • Basil Liddell Hart, Strategy: The Indirect Approach (1967, this is the [revised] fourth edition of the work).
  • Edward N. Luttwak, Strategy: The Logic of War and Peace (1987, 2001).xvi
  • J.C. Wylie, Military Strategy: A General Theory of Power Control (1967, 1989).xvii
  • Niccolo Machiavelli, The Art of War (1520).xviii

All eight books deserve the ascription of classic to differing extents, though obviously a question mark must hang over the twentieth-century works by Liddell Hart, Luttwak and Wylie. To be a candidate for classic status a work has to stand the test of time. There is no rule advising us just how much time is required, but plainly the concept of the instant classic, so beloved by journalists and some publishers, has to be an oxymoron. All studies of strategy and war cannot help but bear the stamp of their historical context of authorship. And nearly all of them are fatally flawed as a consequence, at least with respect to their likelihood of being regarded by future generations as anything more than interesting period pieces.

The bad news, therefore, is that the trees that have been cut to produce books on allegedly strategic topics over the centuries has bequeathed to us less than two handfuls of truly outstanding general works of strategic theory. The good news, however, is that among the eight books that were retained three unarguably are of the highest quality. It is no exaggeration to claim that On War by Clausewitz, Sun-tzu’s Art of War and Thucydides’ Peloponnesian War are works of genius. But even in such elevated company, Clausewitz is outstanding.

It would be difficult to overstate the understanding, insight and educational value of Clausewitz, Sun-tzu, and Thucydides. An army general could make for himself this maxim: If Clausewitz, Sun-tzu, and Thucydides did not say it, it probably isn’t worth saying. Despite the poverty of most efforts at developing a general theory for strategy, the Clausewitz, Sun-tzu and Thucydides classics enjoy a secure intellectual dominance rarely achieved by any book or cluster of books in any field of scholarship.

These three authors, writing so far apart historically, and theorizing in radically different ways, have not only set a standard of excellence that is near impossible to emulate, but have, literally, done the job that needed doing. Thanks to their efforts, hugely divergent though they are in form, we have at hand an adequate theory of strategy nested in a general theory of statecraft.

The beginning of a sound strategic education is familiarity with, and understanding of, the arguments in all three books. As noted already, they are very different. Clausewitz’s On War is a philosophical tract which provides a theory of the nature, actually the natures, of war and strategy. To understand war, there is no better guide than the Prussian.

The heart of Clausewitz’s theory is the “trinity” of 1) popular passion; 2) fortune, opportunity, and risk; 3) reason. These constituent elements are generally associated most closely with, respectively, the people, the army and its commander, and policy.xix Clausewitz also insists that war is a duel, a realm of uncertainty, and that friction intrudes at every step to hinder the smooth execution of cunning plans. He emphasizes the moral over the material factors in war, albeit without discounting the latter.

Above all else Clausewitz demands that force must be used only as a political instrument. That point may seem obvious to the point of banality but in practice, in war after war, armies have fought with scant real direction by policy. When engaged in warfare it can be difficult to remember that the purpose of the bloody enterprise is not just to win, as in a game, but to secure a desired political outcome. Consequently, the manner in which one fights is certain to have political consequences.

In contrast to the philosophical character of, and meticulous detail in, On War, Sun tzu’s Art of War is terse almost to a fault and, necessarily as a consequence, highly abstract. But notwithstanding its extreme brevity, the Art of War bears much the same educational message as does Clausewitz’s On War.xx There are some important differences of opinion between the two. Sun-tzu favors deception, emphasizes the role of surprise, intelligence, and spies, and does not draw attention to the role of friction and all the reasons why well wrought plans can unravel; at least he does not do so explicitly. However, he does insist upon the critical significance of understanding both the enemy and oneself.xxi

It is interesting to note that Sun-tzu’s emphasis on the necessity of understanding the enemy has recently been rediscovered by the U.S. defense community. Diversity in culture is now recognized in Washington as an important factor which has consequences for both deterrence efforts and war.

The third of the masterworks, Thucydides’ Peloponnesian War, is probably the most difficult to glean for strategic understanding. Whereas Sun-tzu’s Art of War is written as a brief to the emperor – it would make a perfect, if lengthy, PowerPoint presentation – and Clausewitz is explicitly theoretical from the very first page, Thucydides wrote a history book. The Greek soldier-historian deliberately tied his general wisdom to a historical narrative. The Peloponnesian War is not a work of abstraction or philosophy. This means that to understand war, peace, and strategy from Thucydides’ writing one has to comprehend the historical context. The result is immensely satisfying, but it must frustrate a busy soldier or politician who is used to receiving his or her strategic education via PowerPoint slides.

As to the merit in Thucydides, one can do no better than to quote the opinion of one of America’s most outstanding soldiers, General of the Army George Catlin Marshall. Speaking at Princeton University on February 22, 1947, Marshall, then Secretary of State, expressed the view that he harbored grave doubts as to “whether a man can think with full wisdom and with deep conviction regarding certain of the basic international issues today who has not at least reviewed in his mind the period of the Peloponnesian War and the Fall of Athens.”xxii That could be a perfect quote for a book’s jacket endorsement.

Clausewitz, Sun-tzu and Thucydides should all be read and reread: they are not alternatives. Neither, of course, are they the last word, not even when regarded collectively. Clausewitz in particular has attracted a great deal of hostile commentary, especially in Britain, for his alleged preference for battle on a large scale.xxiii However it suffices to say that, to date at least, none of his critics has laid a serious glove on him, though it has not been for want of trying.

Each of the five works cited earlier as second tier contributions to our understanding of strategy each has solid, if limited, merit. In the judgment of a majority of strategic theorist each either is, or is likely to be, recognized as a strategic classic. Jomini’s Art of War is crammed with sensible reasoning and good advice, as well as, one must add, much that is better ignored. Liddell Hart has useful things to say about grand strategy in contrast to the more narrow military strategy, while Edward N. Luttwak breaks new ground in his exhaustive examination of strategy’s uniquely paradoxical nature.

J.C. Wylie’s Military Strategy is probably the finest general study of strategy in any language written in the past century. His central idea is profoundly Clausewitz an, and this is entirely appropriate. Wylie claims persuasively that the ultimate object of strategy is control over the enemy. This seemingly simple notion is actually rather sophisticated. It is an admirable complement to Clausewitz’s insistence that in war our object is “to impose our will on the enemy.”xxiv All too often commanders have behaved, indeed have been permitted to behave, as if the object of using military force in action is to cause death and destruction as ends in and of themselves.

Finally, Machiavelli’s Art of War, apart from its overdone admiration for long lost Roman merits, real and imagined, is a goldmine of good advice and prudent reasoning on statecraft and the conduct of war as an instrument of policy.


This article has argued that there is a general theory of strategy which has profound significance as a source of necessary education for politicians and generals and those who would criticize them. We are fortunate in possessing three works of the highest value, true classics by any definition, in Clausewitz’s On War, Sun-tzu’s Art of War and Thucydides’ Peloponnesian War. These three works, collectively, must form the basis of anyone’s strategic education. They have no rivals in any language. The fact that these three classics were written so far apart chronologically (400 BC – 1832), in such different cultural contexts (ancient China, ancient Greece, nineteenth century Prussia), and in such distinctive ways (a briefing for the Emperor, a history book, a philosophical treatise), adds immeasurably to the confidence which we can place in them.

This article appeared at Khazar Journal of Humanities and Social Sciences and is reprinted with permission.

1. Cohen Eliot A., “A Revolution in Warfare, Foreign Affairs,” March/April 1996, pp. 37-54.
2. B.H. Liddell Hart, Strategy: The Indirect Approach (London: Faber and Faber, 1967), 31, 336.
3. See Hew Strachan, “The Lost Meaning of Strategy”, Survival, Vol. 47, No. 3 (Autumn 2005): 33-54.
4. Carl von Clausewitz, On War, edited and translated by Michael Howard and Peter Paret (1832; Princeton, NJ: Princeton University Press, 1976), 75.
5. See Williamson Murray and Mark Grimsley, “Introduction: On Strategy”, in Murray, MacGregor Knox, and Alvin Bernstein, eds., The Making of Strategy: Rulers, States, and War (Cambridge: Cambridge: Cambridge University Press, 1994), 22.
6. See Robert M. Citino, The German Way of War: From the Thirty Years War to the Third Reich (Lawrence: University Press of Kansas, 2005).
7. Geoffrey P. Megargee, War of Annihilation: Combat and Genocide on the Eastern Front, 1941 (Lanham, MD: Rowman and Littlefield Publishers, 2006).
8. Bernard Brodie, “The Continuing Relevance of On War”, in Clausewitz, On War, 53.
9. Helmuth von Moltke, Moltke on the Art of War, edited by Daniel J. Hughes (Novato, CA: Presidio Press, 1993), 47.
10. See Andrew F. Krepinevich, The Army and Vietnam (Baltimore: The Johns Hopkins University Press, 1986); and also John A. Nagl, Learning to Eat Soup with a Knife: Counterinsurgency Lessons from Malaya and Vietnam (Chicago: The University of Chicago Press, 2005), ch. 7.
11. Bernard Brodie, War and Politics (New York: Macmillan, 1973), 452.
12. On the concept and reality of strategic history, see Mazarr Michael J., The Military Technical Revolution: A Structural Framework, Washington, CSIS, March 1993.
13. Sun-tzu, The Art of War, translated by Ralph D. Sawyer (ca. 400 BC; Boulder, CO: Westview Press, 1994).
14. Thucydides, The Landmark Thucydides: A Comprehensive Guide to “The Peloponnesian War,” edited by Robert D. Strassler (ca. 400 BC; New York: The Free Press, 1996).
15. Antoine Henri de Jomini, The Art of War (1838; London: Greenhill Books, 1992).
16. Edward N. Luttwak, Strategy: The Logic of War and Peace, revised edition (1987; Cambridge, MA: The Belknap Press of Harvard University Press, 2001)
17. J.C. Wylie, Military Strategy: A General Theory of Power Control (Annapolis, MD: Naval Institute Press, 1989).
18. Niccolo Machiavelli, The Art of War, translated by Henry Neville (1520; Mineola, NY: Dover Publications, 2006).
19. Clausewitz, On War, op. cit., 89.
20. The similarity of argument among the classics is a major theme of Michael I. Handel, Masters of War: Classical Strategic Thought, 3rd edition (London: Frank Cass, 2001).
21. Sun-tzu, The Art of War, 179.
22. General George C. Marshall, quoted in Paul A. Rahe, “Thucydides as educator”, in Williamson Murray and Richard Hart Sinnreich, eds., The Past as Prologue: The Importance of History to the Military Profession (Cambridge: Cambridge University Press, 2006), 99.
23. The anti-Clausewitz literature is roughly handled in Christopher Bassford, John Keegan and the Grand Tradition of Trashing Clausewitz: A Polemic, War in History, Vol. 1, No.3 (November 1994): 319–36.
24. Clausewitz, On War, op. cit., 75.

Richard Rousseau

Richard Rousseau, Ph.D., is an international relations expert. He was formerly a professor and head of political science departments at universities in Canada, Georgia, Kazakhstan, Azerbaijan, and the United Arab Emirates. His research interests include the former Soviet Union, international security, international political economy, and globalization. Dr. Rousseau's approximately 800 books, book chapters, academic journal and scholarly articles, conference papers, and newspaper analyses on a variety of international affairs issues have been published in numerous publications, including The Jamestown Foundation (Washington, D.C.), Global Brief, World Affairs in the 21st Century (Canada), Foreign Policy In Focus (Washington, D.C.), Open Democracy (UK), Harvard International Review, Diplomatic Courier (Washington, C.D.), Foreign Policy Journal (U.S.), Europe's World (Brussels), Political Reflection Magazine (London), Center for Security Studies (CSS, Zurich), Eurasia Review, Global Asia (South Korea), The Washington Review of Turkish and Eurasian Affairs, Journal of Turkish Weekly (Ankara), The Georgian Times (Tbilisi), among others.

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