‘War is an act of violence to compel our opponent to fulfil our will. War is an act of violence pushed to its utmost bounds.’
Carl von Clausewitz, On War, 1832

ClausewitzCarl von Clausewitz was a complicated man: a loyal patriot who served a foreign army; a softly-spoken individual who expressed himself in resounding language; and an Enlightenment genius with ideas well ahead of his time. Yet there is one central theme that makes sense of his life: war.

Born in 1780, Clausewitz was not even a teenager when he signed up for the military, and he first saw action as a 13-year old cadet. Curiously, Clausewitz’s initiation was in skirmishes against guerrillas and small-town insurgents (most notably, the young Clausewitz helped stamp out a citizen-led revolution in Mainz). It was the opposite of the grand-scale confrontations now associated with his name.

Clausewitz soon entered Prussia’s elite military academy, the Kriegsacademie in Berlin, where his experiences of war came to be underpinned by theory. He studied philosophy, notably that of Immanuel Kant, another Prussian and the exponent of a scientific approach to ethics.

Kant came close to defining what people should do (many modern-day philosophers think he succeeded), but Kant famously concluded ‘out of the crooked timber of humanity nothing straight was ever built’.

It must have influenced Clausewitz greatly, because, like Kant, he came to develop a ‘science’ for another very human activity – war – and, like Kant, Clausewitz concluded the large-scale imperfection was inevitable.
Clausewitz graduated from the academy top of his class.

He soon impressed his seniors, notably the Prussian Prince August, who was 50 years older than Clausewitz; together they faced Napoleon at Jena in October 1806. The battle was a disaster for the Prussians, who were routed by the French Emperor’s much smaller force. As the Prince’s Chief-of-Staff, Clausewitz would have had first-hand experience of the failures which led to his army’s collapse: a confusing command structure, over-elaborate planning processes, and – perhaps most importantly – a dissonance between the commander’s vision and the instincts of his soldiers, such that Prussian operations lacked the will and initiative to succeed.

Clausewitz was wounded and, alongside 25,000 other soldiers, captured when the Prussians surrendered. He went on to spend a humiliating year under detention in France, while Prussia itself was split in two as Napoleon imposed his terms (a division which eerily foreshadowed the division of the defeated Nazi Germany by the Allies some 139 years later).

Clausewitz studied while in captivity, and used the time to refine his ideas. His fierce patriotism was soured with recognition of widespread failings in the Prussian military system, and he pressed for it to be modernised – in part through the adoption of Napoleonic innovations like mass conscription and more meritocratic (rather than aristocratic) appointments.

When, in 1812, the French strong-armed the Prussians to join the ill-fated incursion into Russia, Clausewitz resigned his commission and joined a unit under Russian command. He fought at Borodino – a bloody, pyrrhic victory for Napoleon, since the Emperor’s troops were forced to march back over the same battlefield, still littered with decaying corpses, several months later, in retreat from Russia’s ‘General Winter’.

The episode must have helped crystallise in Clausewitz’s mind the distinction he later made clear in his writing between battlefield victory and success in war. The two are connected, but the link is by no means automatic.

As Napoleon became increasingly vulnerable, Clausewitz helped tip Prussia against their overlord, and rejoined his compatriots in the fighting until the French defeat of 1814.

When Napoleon returned from exile the following year, he would face an army at Ligny in which Clausewitz was once again Chief of Staff. It was the emperor’s last battlefield victory, but a strategic defeat, since the Prussians ultimately tied down more than their own number of French troops and were still – just – able to join Wellington at Waterloo two days later. Clausewitz’s military genius was in the ascendant as Napoleon’s was in decline.

Clausewitz was just 35 when the Napoleonic Wars ended, but he stayed with the army, and was promoted to the rank of major-general in 1818 and put in charge of the Kriegsacademie. It was the perfect appointment for him – he was able to spend the next 12 years pondering all he had witnessed, determined to ensure that Prussia would never be humiliated again, while trying to develop an underlying theory or concept of war.

But what makes Clausewitz special – and explains why he is still so widely studied today – is that he sought insights beyond the battlefield. War had certainly been revolutionised by the French Revolution and Napoleon: artillery was more lethal, conscription had created mass armies, and the morale and motivation of citizen-soldiers was now critical. But Clausewitz, working as Chief-of-Staff, with commanders and political leaders above him and the officer class below, saw more permanent features of warfare, such as the circular relationship between politics and the military, and the centrality to battle of resolve and perception.

Napoleon’s early successes came, in part, because he brought political and military objectives into line, and infused them with shocking new tactics based on speed and audacity. His later defeats occurred when his enemies could mobilise matching resources and copy the Emperor’s technique. More than a century later, Hitler’s trajectory followed a very similar course, and Clausewitzian analysis still applies almost perfectly.

Ironically for such a martial figure, Clausewitz was not killed by a blast or a bullet, but by a bacterium. In 1831, while trying to seal Prussia from an outbreak of cholera in the east, Clausewitz caught the disease himself and died in Poland.

His grand opus, On War, was completed by his wife, Marie, and published a year after his death. It is a suitably complex read for such an intriguing figure. The book seems full of riddles, paradoxes, and contradictions; at the same time, there is a beautiful, poetic brilliance to it – much like Clausewitz himself.


That article appeared in issue 45 of Military History Monthly.



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