Carl von Clausewitz's On War

A Biography (A Book that Shook the World)

Hew Strachan

• Publisher: Atlantic Books
• Year: 2013
• Print ISBN: 9781843543923
• eBook ISBN: 9781782392170
• Topic: History
• Subtopic: European History
• Index: History

On War by Carl von Clausewitz was first published in Germany after the Napoleonic Wars. One of the most significant treatises on military strategy ever written, it is still prescribed at various military academies today. Its description of 'absolute war' and its insistence on the centrality of battle to war have been blamed for the level of destruction involved in both the First and Second World Wars. Hew Strachan's accessible book challenges the popular misconceptions that surround On War. He dispels the notion that for Clausewitz policy necessarily shapes war, asserting instead that war has its own dynamic and that its reciprocal effects can themselves shape policy. Strachan returns to the very heart of On War to recover the arguments at its core; in the process challenging the received wisdom about this cornerstone of military strategy.

CHAPTER 1

The Reality of War

For a man now best known as an author, Clausewitz was remarkably cynical about the genre in which he was to establish his posthumous reputation. He accused his contemporaries who wrote about war of those very failings with which he himself has been charged – vagueness, mystification, abstraction and pseudo-science. His concern, he stressed repeatedly, was to keep his analysis rooted in reality. ‘Just as some plants bear fruit only if they don’t shoot up too high’, he declared in a Preface to an unpublished work on war written between 1816 and 1818, ‘so in the practical arts the leaves and flowers of theory must be pruned and the plant kept close to its proper soil – experience.’¹

Clausewitz was able to deliver precisely because his own experience of war was so intense and so pervasive. He served throughout the wars of the French Revolution and of Napoleon, from 1792 until 1815, the most prolonged and violent series of conflicts to assail Europe between the Thirty Years War (1618–48) and the First World War (1914–18), and for many commentators (including Clausewitz himself) the foundation of modem war. ‘My entry to the world was to an arena of great opportunities, in which the fate of nations would be decided,’ he wrote to his fiancée, Marie von Brühl, in 1807. ‘Thus my gaze fell not on the temple in which domesticity celebrates its quiet good fortune, but on the triumphal arch through which the victor passes when the fresh laurel wreath cools his glowing brow.’²

That did not happen: Clausewitz never became the conquering hero. His lust for glory outstripped his achievements. He lived in the age of Napoleon, Wellington and, from Prussia itself, Gebhard von Blücher, but he was younger than they; too young to achieve high rank in the wars in which he took part, even if he had deserved it. He confessed that his constant sense of dissatisfaction, of lack of fulfilment, might well have been attributable to thwarted ambition. He would rather have exercised high command than written about it. None the less, he was not a professional failure. By the age of thirty-eight he had become a major-general. Moreover, he found his vocation in war. Military service in peacetime gave him little satisfaction. He would have preferred, if he could have afforded it (which he could not), to have retired to the country to study and write.³ He made his motives for being a soldier clear in a letter to Marie on 1 September 1807: ‘If men have degraded our manly honour, then men must also be able to regain it; I don’t mean through the conditions of peace and its weak means; war opens a broad field for energetic means, and if I am frank about the innermost thoughts of my soul, for me they are the most mighty of all; I would arouse the lazy beasts with cracks of the whip and teach them to break the shackles in which they have let themselves be placed by cowardice and fear.’⁴

Clausewitz’s chilling words, the suggestion that war purges decadence and revitalizes national life, resonate beyond his own times, pointing forward to the ideas of Fascism. However, the context in which he penned them was specific. He had just heard the terms of the treaty of Tilsit, the confirmation of Prussia’s abject humiliation at the hands of France on the battlefield the year before. His homeland had been stripped of half its population and a third of its territory, and the army in which he served was reduced to a sixth of its former size. Later in life, reflecting in peacetime on the course of military history, he was able to see what individual circumstance meant for attempts to generalize about the nature of war. ‘Every age has had its own peculiar forms of war, its own restrictive conditions, and its own prejudices,’ he wrote in Book 8, Chapter 3, of On War. ‘Each, therefore, would also keep its own theory of war, even if everywhere, in early times as well as in later, there had been an inclination to work it out on philosophical principles. The events of each age must, therefore, be judged with due regard to the peculiarities of the time, and only he who, less by an anxious study of minute details than by a shrewd glance at the main features, can place himself in each particular age is able to understand and appreciate its generals.’⁵

To comprehend On War, it too has to be placed in the context in which it was written. It is first and foremost a response to one man’s experience and to the wars through which he lived and in which he served.

Carl Clausewitz was born on 1 June 1780 ⁶ in Burg, close to Magdeburg. His grandfather was professor of theology at Halle. Both his great-grandfather and great-great grandfather were Lutheran pastors, themselves married to daughters of the clergy, and this was the calling for which one of Carl’s elder brothers also prepared. Clausewitz’s wife believed his gifts were God-given.⁷ ‘Religion’, he wrote to Marie, ‘should not take our gaze from this world; it is a heavenly power which walks in step with the noble things of life, and religious feeling has never yet run through me and strengthened me without inspiring me to good deeds, without giving me a wish – yes, even a hope – of something greater than me.’⁸ However, Clausewitz himself made little reference to religion and less to his own beliefs in his writings. He displayed the almost unconscious anti-Semitism of his times.⁹ Faith was not cited as a motivation for war or in war; Christianity was not seen as an impulse for moderation in fighting fellow Christians, or for excesses against those of other religions. But in 1807 he visited Reims Cathedral, and, although his initial reactions were historical and architectural, its Gothic splendours moved him to spiritual reflection and to admiration of the patterns of Christian worship. ‘The greatness of the founder, who has awakened these sentiments in the bulk of the human race, is astounding, at a time when false doctrines on the one hand and barbarous brutality on the other appear more than ever to have distanced it from mankind.’¹⁰ On War makes full use of analogies drawn from Clausewitz’s eclectic readings across other fields of human endeavour – pre-eminently philosophy, but also the law, the sciences, the arts; unsurprisingly, but less obviously, the text is also marked by the scriptures on which Clausewitz was raised.

Much more direct an influence on the young Clausewitz than the Church was the army. ‘I am a son of the camp, but from a real one, not from Schiller’s poetic world like Max Piccolomini,’ Carl told Marie.¹¹ In 1786, when Frederick the Great died, nine-tenths of Prussian officers were noble; among those whose names enjoyed the right to the prefix ‘von’ was Marie’s own family. Clausewitz’s did not. Carl was clearly sensitive on the point: to impress his inamorata, he created a bogus lineage, designed to show that he was sprung from Silesian aristocracy. In fact, his father had served as a junior officer in the Prussian army during the Seven Years War (1756–63), but precisely because he was not noble he had been retired when the size of the officer corps was cut back after the war. He used the title ‘von’ because he had been an officer; not until 1827 would his family’s entitlement to it be formally sanctioned by the king.

At the time of his birth, Clausewitz’s father was a minor official. However, Burg was the town where the regiment in which he had passed his wartime service was quartered. In Clausewitz’s own words, ‘he grew up in the Prussian army’.¹² His father’s old comrades frequented the house, and the talk was of soldiering. They were entitled to rest on their laurels. The Prussian army was the admiration of Europe. In 1756 it had faced a coalition of Austria, France and Russia, the first of whom had been determined to reconquer Silesia, seized by Frederick the Great on his accession to the throne of Prussia in 1740, and possibly even to obliterate Prussia as an independent state. On 4 December 1757, the evening before the battle of Leuthen, Frederick’s most comprehensive and famous victory over the Austrians, the king had told his officers that they were fighting for their homes and families. On the following evening, reflecting the Pietism in which Clausewitz was brought up, the survivors spontaneously took up the refrain of Luther’s great hymn, ‘Now thank we all our God’.

The Prussian army was outnumbered two to one at Leuthen and by nearly three to one by the allies that it faced in 1756. But it prevailed and Prussia survived. Despite being ranked thirteenth in Europe in terms of population, Prussia raised an army that was the fourth biggest. It did so by the canton system, a form of compulsory military service which rendered peasants liable for military obligations as well as feudal. Although, like other eighteenth-century armies, it relied also on mercenaries, especially in peacetime, this was an army with an incipient national identity. Moreover, the army was the embodiment of the state. Its commander, the outstanding general of the age, was also its king. Its campaigns expanded and defined its national frontiers. And within those frontiers the economy, the taxation system and the bureaucracy were bent to providing the infrastructure to support the state’s use of military power.

When Prussia emerged, battered but in one piece, from the Seven Years War, military visitors flocked to Potsdam to see what it was that had underpinned the army’s performance in the field. They marvelled at the drill and discipline which had given Frederick’s forces the tactical facility to prevail on the close-order battlefield. They paid less attention to the rumblings of reform in France, whose army had been humiliated by Frederick at Rossbach a month before Leuthen. Frederick himself resisted the tactical innovations pioneered not only in campaigns outside Europe, specifically in America, but also on the continent’s peripheries, in mountains, forests and uncultivated wastelands. Here troops dispersed, used cover, and fought more as individuals than as members of closely drilled units. Late eighteenth-century Prussia was even more unhappy with the political and social reforms which some argued underpinned greater tactical flexibility. The message from America was that free men fought best and did so because they were citizens.

This was an argument picked up by a French aristocrat and veteran of the Seven Years War, Jacques-Antoine-Hippolyte, comte de Guibert, in his Essai général de la tactique (1770). Like others, Guibert lauded Frederick; in 1773, he made the pilgrimage to Prussia, met the king and attended manoeuvres in Breslau. But Guibert pointed forward as well as back. He was Clausewitz’s most obvious immediate intellectual predecessor, although it is a link about which Clausewitz remained largely silent. Significantly, Guibert is not cited in On War, perhaps because most of the military theorists who are were those to whom Clausewitz took exception. But Clausewitz certainly read Guibert. In February 1812, in the third of a series of ‘political declarations’ designed to rally Germans against France, Clausewitz quoted in full one of Guibert’s most famous passages: ‘Let us suppose in Europe, there was to spring up a people, with genius, with power, and a happy form of government; a set of people that to strict virtue, and to national soldiery, joined a fixed plan of aggrandizement, who never lost sight of that system, who knowing how to carry on a war with little expence, and to subsist by their conquests, was not reduced to the necessity of laying down their arms by financiers. As the north wind bends the tender reed, those people would be seen to subjugate their neighbours, and overthrow our feeble constitutions.’¹³

Guibert went on to deny that such a people would ever appear, but he was more prescient than he realized, as Clausewitz knew full well by 1812. Very few changes in the conduct of war, according to On War, ‘can be ascribed to new inventions or new departures in ideas’; instead, they arise ‘mainly from the transformation of society and new social conditions’.¹⁴ The basis for Clausewitz’s belief was quite specific. In 1789 revolution in France maximized the power of the state through its claim that citizenship gave it an authority more complete than that exercised by absolute monarchs like Frederick and his successors. In February 1792 Prussia formed a defensive alliance with Austria, responding to the latter’s commitment to the defence both of its own possessions in the Netherlands and to the German principalities in the Rhineland. In April the French attacked Austria and in June Prussia declared war on France. ‘It was expected that a moderate auxiliary corps would be enough to end a civil war’, Clausewitz wrote, ‘but the colossal weight of the whole French people, unhinged by political fanaticism, came crushing down us.’¹⁵

That same spring the youthful Clausewitz was accepted into the 34^th Prussian Infantry Regiment (Prince Ferdinand’s), whose previous commanding officer had been his father’s stepbrother, and in which one of his elder brothers was already serving. In 1793 the twelve-year-old found himself in the trenches besieging Mainz. Here the adolescent Clausewitz witnessed at first hand the clash between the armies of the old order and the new. The outstanding Austrian commander of the war, Archduke Charles, reflected a common belief when he attributed the allies’ defeat not to the enemy, the French, whose military organization seemed to be chaotic, but to the internal failings of the allies themselves. Austria and Prussia were divided not just by the conduct of the war in north-west Europe but also by their competition for the territory offered by the partition of Poland. The problems of coalition warfare were to constitute a recurrent theme of On War. However, a Hanoverian officer of even humbler origins than Clausewitz, Gerhard Scharnhorst, concluded that the consistency of France’s victories was to be found in the hearts of Frenchmen: ‘they believed that they alone are enlightened, clever, free and lucky and that all other nations are backward, bovine and unlucky… They believed that they were fighting not only for their own future existence and fortune, but also for that of all mankind.’¹⁶ In April 1795 Prussia conceded all territory on the left bank of the Rhine to France, and consoled itself with its gains in Poland and its domination of north Germany.

Prussia now enjoyed nearly a decade of peace and neutrality. As hostilities ended in the spring of 1795, Clausewitz was billeted with a Westphalian peasant family for three to four months. ‘Withdrawn from war, and transferred to the calm of rural life in all its meaning, for the first time my spirit looked inwards.’¹⁷ Nearby Osnabrück provided the books which launched the fifteen-year-old on the path of self-education. Clausewitz began with the writings of the Enlightenment, and was sufficiently drawn to philosophy to begin to doubt his vocation as a soldier. His comrades were ordinary men, content to settle into the routine of post-war garrison life in Neuruppin. However, his commanding officer reflected the spirit of the age in his belief in the value of education. He had no truck with the idea that reading and writing would make private soldiers discontented with life in the ranks, or – even worse – turn them into political radicals. On the contrary, he held that basic literacy and arithmetic would make them more proficient in their military duties. His officers, and Clausewitz above all, benefited from both his policies and his library. As well as the works of Schiller, Goethe and Hölderlin, Clausewitz began reading military history. And so the tension between this newly discovered and exciting inner world and the outer world of military ambition found some sort of reconciliation.

The process was taken a stage further in late 1801, when he entered the war school in Berlin, the Berliner Allgemeine Kriegsschule, revitalized by Scharnhorst, who had forsaken the service of Hanover for that of Prussia. The French revolutionary wars had convinced Scharnhorst that the armies of Germany had to be reformed, that they should be recruited through compulsory but universal military service, that promotion should be by merit, that education could develop talent, and that tactical innovation was predicated on social and political change. These were potentially unsettling arguments for a monarchy concerned by the spread of revolutionary ideas from France. Nor were its fears simple reflections of conservatism. The Terror, which had purged the aristocracy of France, had found its application on the battlefield: the armies, which said they brought liberty, equality and fraternity, also raped, looted and pillaged. None the less, Scharnhorst was free to teach and to set up a military discussion group, the Militärische Gesellschaft, attended by civilians as well as soldiers.

Scharnhorst’s relationship with Clausewitz – at once paternal and pedagogic – was of decisive importance. Twice Clausewitz’s age, he was, Clausewitz said, ‘the father and friend of my intellect and of my spirit’.¹⁸ Crucially, Clausewitz’s own father had died in 1802, just as he and Scharnhorst met. Politically, Scharnhorst was not a radical, but he was a reformer, a product of the Enlightenment. France had tapped the resources of its people by revolution; Prussia could do it by giving them rights before the law, by emancipating the serfs, and by providing universal systems of education. Liberalizing Prussia would save it through reinvigoration, and the pay-off would be on the battlefield. Scharnhorst had imbibed the ideas of the Enlightenment in a military context, at the military academy of Crown Prince Wilhelm of Schaumburg-Lippe. The author of two military manuals, he emphasized the importance of theory, but taught that it should be derived from correct concepts, grounded in the nature of things and in practical experience. The role of theory was to elucidate events, and so reason alone was insufficient. Detailed military history was required to ...

Table of contents

• Cover
• Title Page
• Contents
• Introduction
• 1 The Reality of War
• 2 The Writing of On War
• 3 The Nature of War
• 4 The Theory of War
• Conclusion
• Notes
• Sources and Further Reading
• A Note on Translations and Editions
• About the Author
• Acknowledgements
• Index
• Copyright