Vegetius, a Roman writer of the fourth century AD, said, "Let him who desires peace prepare for war." Carl von Clausewitz sharpened the point: "The fact that slaughter is a horrifying spectacle must make us take war more seriously, but not provide an excuse for gradually blunting our swords in the name of humanity. Sooner or later someone will come along with a sharp sword and hack off our arms." Darfur has made clear that that is not just a metaphor.
Clausewitz (1780-1831) studied total war. Although he knew nothing of tanks, air forces, or satellite communications, he knew from combat how wars kill, confuse, and terrify. In war studies, expertise matters enormously; he had plenty.
At the age of 12, Clausewitz joined two brothers as cadets in the Prussian army. (Eventually all three became generals.) He fought for Prussia against Napoleon at Jena, was captured, taken to Paris, exchanged, and returned to duty. When Prussia was intimidated into joining Napoleon for his disastrous 1812 campaign, Clausewitz resigned his commission and fought for the czar. In 1815, again with the Prussian army, he fought at Ligny. In 1818 he became director of the Military Academy in Berlin, where he devoted the last 15 years of his life to scholarship. His major work, On War (three volumes of Vom Kriege were published, from 1832 to 1843), was left unfinished at his death.
On War has become something of a classic, often cited, discussed in numerous recent books, seen in the company of Sun Tzu's Art of War (thought to be circa fourth century BC), and studied in military academies. On War appeals to anyone who wants to see how a general thinks, and to all who suppose that warcraft applies to an office, company, college, or team. Clausewitz himself compared war with commerce and alliances with "a business deal."
With protracted wars in Iraq and Afghanistan, American and British readers have found On War to be a touchstone for discussions about tactics, strategy, war aims, and definitions of "victory." What might Clausewitz help us understand? David H. Petraeus and James F. Amos's Counterinsurgency Field Manual—the book that framed the change of U.S. strategy in Iraq—quotes Clausewitz: "The first, the supreme, the most far-reaching act of judgment that the statesman and commander have to make is to establish … the kind of war on which they are embarking; neither mistaking it for, nor trying to turn it into, something that is alien to its nature. This is the first of all strategic questions and the most comprehensive." "The first, the supreme": That's Clausewitz.
"The great deeds in the history of warfare cannot be imputed to books," he wrote, bringing to war the same stern realism that Machiavelli brought to statecraft.
In Clausewitz's Puzzle: The Political Theory of War (Oxford University Press, 2007), Andreas Herberg-Rothe, a private lecturer at Humboldt University, in Berlin, argues that what makes Clausewitz worth reading is his probing analysis of Napoleon's campaigns: their tendency toward unrestrained violence, the vital importance of leadership, the role of chance, the role of politics, and the calamities of an invasion like the Russian campaign of 1812.
Great warriors study great warriors. Caesar studied Alexander. Charlemagne studied Caesar. Napoleon advised strategists that the only way "to master the secrets of the art of war" was to study the campaigns of the great generals. Stonewall Jackson carried the Military Maxims of Napoleon with him through his Civil War campaigns. The Art of War, by Général Antoine Henri, baron de Jomini (who served with Napoleon), became a textbook for both sides of the war. Eisenhower read On War three times. Among its other virtues—pith, passion, comprehension—it is a learned book, heavy as cannon.
Clausewitz himself studied the wars of Frederick the Great and Gustavus Adolphus as well as those of Napoleon. General Helmuth von Moltke, hero of the German victories in 1864, 1866, and 1871, cited On War as one of his three guiding books (the other two were Homer and the Bible). It has been taught at West Point and Sandhurst.
Clausewitz valued history, taught and wrote about it as something vital for making sense of the world, but never thought history was enough. To study war the Clausewitz way, a warrior must go to war. But I would like to believe that On War makes casualties no longer necessary. What is painfully learned in battle might instead be learned from Clausewitz.
Michael Briggs, editor of the highly regarded military-studies list at the University Press of Kansas, told me in an e-mail message that a military credential "can amplify the credibility of a work of military history, especially if that history is directly related to the veteran's combat experiences. But it is by no means a necessary credential for such work to be respected and valued within the field—which includes academics, military professionals, military buffs, and general readers."
Clausewitz was a general, yes, but he spent most of his career as an educator. He was tutor to a prince, a teacher of cadets, director of a military academy, and a gifted military historian. He wanted to write a war book of a much higher order than existing maxims and manuals, a book that would combine experience, historical examples (the more recent the better), and exact analysis in a clear and emphatic fashion. A careful scholar, Clausewitz revised drafts of his books again and again, On War among them. He was revising it when he died of cholera.
His motives were pure Prussian. Viewed in hindsight as the prophet of blitzkrieg and total war, which blurs the distinctions between combatants and noncombatants, Clausewitz was instead preoccupied in defending fragmented Prussia against invasions by its mighty neighbors, France, Austria, and Russia. In the balance of power of his era, he understood that Prussia was one of the lightweights.
Even in a small country, war is a tremendous subject. No doctrinarian he: "In war everything is uncertain." He sought a better way to think about war and succeeded so well that the French social scientist Raymond Aron dubbed him "the philosopher of war." Such a distinction commands attention.
On War became the war book of a unified Germany, invoked on all sides of military debates. It achieved the highest dignity, to be quoted against itself: for the supremacy of aggression or defense, for annihilation or attrition, for total war or armed peace. Aron saw, "You can find what you want in the Treatise: All that you need is a selection of quotations, supported by personal prejudice." True, but that is not the fault of On War, just some readers.
For example, in 1943, Allied bombers dropped leaflets over Germany that said Hitler should have read Clausewitz more carefully. Hitler responded in 1944, in a preface to a new edition of Vom Kriege, accusing others of misunderstanding it. Hitler said: "Clausewitz wrote that even after a heroic defeat a reconstruction is always possible. Only cowards surrender." Bah. Clausewitz in fact warned: "Strength of character can degenerate into obstinacy … a fault of temperament." The leaflets were right. Hitler should have read Clausewitz more carefully.
Disputes about Clausewitz—Is he vicious? Contradictory? Obsolete?—heat up the scholarship about him. His attackers (like the military historians Martin van Creveld, B.H. Liddell Hart, and John Keegan) have been met with fierce defense and counterattack by younger scholars (Christopher Bassford, Antulio J. Echevarria II, Herberg-Rothe, Hew Strachan), who seem to be winning.
Stressing that genius "is above all rules," Clausewitz appeals to every reader's vanity. Like all thinkers of deep thoughts, he despised rote: He wanted to teach how to think. On War attracts thinkers. Scholars have compared reading Clausewitz to reading Hegel, Kant, and Max Weber.
On War is rich in vivid and memorable passages. For example: "The character of battle, like its name, is slaughter"; "Truth in itself is rarely sufficient to make men act." Irony clangs in "The aggressor is always peace-loving." Concepts and phrases in On War need to be teased out. These days much is made of Clausewitz's "wondrous Trinity"—"primordial violence, hatred, and enmity"—and its correspondence to the people, the commander, and the king, and to morale, warfare, and politics.
Modern scholarship on Clausewitz has come in two great waves. John Tetsuro Sumida, a historian at the University of Maryland at College Park, describes the first in Decoding Clausewitz: A New Approach to 'On War' (University Press of Kansas, 2008). In 1976 three major works were published: Aron's Clausewitz: Philosopher of War (which Gallimard published in France, and which was brought out in translation by Routledge & Kegan Paul in 1983); a translation of On War (Princeton University Press), by Peter Paret, an American professor of European history, and Michael Howard, a British professor of military history; and Paret's Clausewitz and the State (Oxford), which Strachan, a Scottish historian, has called "the best biography of Clausewitz in any language."
The books by Aron and Paret remain essential reading, the first places to go after or while reading On War. The Paret-Howard translation is the basis for almost all recent commentaries in English. It is much enhanced by three introductory essays, on the genesis, influence, and continuing relevance of On War.
A second great wave of Clausewitz studies is now under way, stimulated by continuing wars. Strachan's Carl von Clausewitz's On War: A Biography (the first American edition by Atlantic Monthly Press, distributed by Publishers Group West, 2007) is fresh, clear, concise, and exceedingly well informed, surveying the current state of Clausewitz scholarship in English and German. Strachan edited, with Herberg-Rothe, Clausewitz in the Twenty-First Century (Oxford, 2007), essays that identify the topics that engage Clausewitz scholars now: textual problems with On War (we know it's unfinished, but how finished is it?), moral forces in war, cyberwarfare, reliance on mercenaries (always a bad idea), and much else.
Since Paret, the best Clausewitz scholars pay close attention to Clausewitz's other writings, too. In one essay in Clausewitz in the Twenty-First Century, Christopher Daase, a political scientist at the University of Munich, rips critics who complain that Clausewitz didn't address guerrilla war. He points out that the author certainly did—but in lectures he gave in 1811-12 more than in On War. In another essay, Echevarria, of the U.S. Army War College, discusses the relevance of On War to the so-called war on terror. In Clausewitz and Contemporary War (Oxford, 2007), he deals at greater length with the pertinence of On War to terrorism and counterterrorism. From Napolean's failure in Spain, Clausewitz learned that to counter terror with greater terror only makes more enemies.
The standard German edition of Vom Kriege is Werner Hahlweg's (Dümmlers Verlag, 1980). It includes an excellent survey of Clausewitz's reception in Germany. Readers unable to navigate German will find Echevarria's After Clausewitz: German Military Thinkers Before the Great War (University Press of Kansas, 2000) a useful surrogate. Christopher Bassford's Clausewitz in English: The Reception of Clausewitz in Britain and America, 1815-1945 (Oxford, 1994) follows the ups and downs of Clausewitz's reputation, finding that there tends to be more attention to him after defeat or Pyrrhic victories: in France after 1872, in Britain after the Boer War, and in America after Vietnam.
Clausewitz in the Twenty-First Century shows that On War is no longer exclusively a military province reserved for officers and veterans. It attracts historians, philosophers, and political scientists. With its fatal topic, its textual problems, its style, and its brave ambitions, On War should soon entice literary scholars as well.
Clausewitz's most quoted remark, "War is merely the continuation of politics by other means," remains central to debates about his continuing relevance. However much wars are alike, they differ as the politics that support them differ—and the relations between war and politics are seldom static. Clausewitz wrote, "Every age has its own kind of war, its own limiting conditions, and its own peculiar preconceptions. Each period, therefore, would have held to its own theory of war."
He reacted against a mode of theorizing that aspired to imitate geometric and mechanical sciences. "Theory cannot equip the mind with formulas for solving problems," he warned, "nor can it mark the narrow path on which the sole solution is supposed to lie by planting a hedge of principles on either side. But it can give the mind insight into the great mass of phenomena and their relationships, then leave it free to rise into the higher realms of action."
Alarmed by war, Clausewitz made two fundamental contributions to its study. First, he insisted on the importance of thinking over doctrine; and second, he believed that such thinking could be taught.
It is fitting that On War, faithful to its subject, was not finished. War had not ended, not then, not yet.