Carl von Clausewitz died in 1831, at fifty-one, without finishing his book. On War was published posthumously, edited by his wife Marie, and for nearly two centuries it has been the most cited, most debated, and most misunderstood text in Western military theory. Everyone knows the phrase: “War is the continuation of politics by other means.” Almost nobody fully understands it. And yet, two hundred years later, there is no better theoretical framework for analysing why states fight, how they fight, and above all, why they so often fight badly.
Clausewitz did not write a manual of tactics. He had no interest in teaching generals how to deploy troops on a battlefield. What he attempted was something more ambitious and rarer: to construct a theory of the nature of war. Not of a particular war, but of war as a human phenomenon. And he did it from experience. Clausewitz enlisted in the Prussian army at twelve, fought in the French Revolutionary Wars, was taken prisoner by Napoleon after the disaster at Jena in 1806, served in the Russian army during the 1812 campaign, and returned to the Prussian ranks in time for Waterloo. Twenty-two years of nearly continuous warfare. From that crucible came On War, a dense, incomplete, sometimes contradictory book, but one that contains insights into the nature of armed conflict no subsequent author has surpassed.
The obvious question is whether a nineteenth-century Prussian officer has anything to say to the twenty-first century, to the age of drones, cyber warfare, hypersonic missiles, and information operations. The answer, which any professional officer in any serious army in the world will confirm, is yes. And the reason is that Clausewitz did not write about technology. He wrote about the political logic of organised violence, and that logic has not changed.
Key Concepts: Friction, the Fog of War, Centre of Gravity
On War is a long book and not always an easy one, but its central ideas can be distilled into a handful of concepts anyone interested in geopolitics should know.
The first and most important is the subordination of war to politics. “War is not merely a political act, but a true political instrument, a continuation of political activity, a carrying out of the same by other means.” This is not a description of how war ought to be. It is a description of what war is. Every armed conflict, however chaotic it appears, has a political objective. If it doesn’t, it is not war: it is pointless violence. And if the political objective is lost from sight, war veers towards disaster. Military history is full of cases where military means consumed the political end, where the logic of battle devoured the logic of politics. Vietnam is one example. Afghanistan is another. Clausewitz would say that in both cases the problem was not military but political: nobody ever clearly defined what was to be achieved.
The second concept is friction. In theory, an army moves according to plan, supplies arrive on time, orders are transmitted without error, and units do what they are told. In practice, none of that happens. Everything is slower, more complicated, and more confused than anticipated. Clausewitz used the metaphor of walking in water: every movement that on dry land is straightforward, in water requires disproportionate effort. Friction is the accumulation of small obstacles, mistakes, misunderstandings, communication failures, logistical breakdowns, adverse weather, that turn an elegant plan into chaos. Friction explains why war never unfolds as planned. And it explains why the capacity to improvise, to adapt to disorder, matters more than the capacity to design perfect plans.
The third is the fog of war. In any conflict, information is incomplete, contradictory, and often false. Commanders make decisions with partial data about the enemy’s position, intentions, and forces. Clausewitz understood that this uncertainty is not a defect of war that can be corrected with better intelligence. It is a constitutive element of war. It is what distinguishes war from a mathematical exercise. War is the realm of uncertainty, he wrote, and three-quarters of the things on which action is based are wrapped in a fog of greater or lesser density.
The fourth concept is the centre of gravity: the point on which the enemy’s ability to sustain the war depends. It may be his main army, it may be his capital, it may be his alliance with an external power, it may be the will of his population. Correctly identifying the enemy’s centre of gravity and directing the main effort against it is, for Clausewitz, the fundamental strategic decision. Getting this wrong means wasting resources attacking secondary objectives while the enemy retains what truly matters.
And finally, the trinity. Clausewitz described war as an interaction between three forces: passion and violence, which belong to the people; chance and probability, which belong to the commander and the army; and political reason, which belongs to the government. A successful war requires these three forces to be aligned. When they fall out of alignment, when the people lose the will to fight, when the army cannot translate popular passion into military capability, when the government loses sight of the political objective, the war fails.
Application in Modern Conflicts
The war in Ukraine is probably the best Clausewitzian laboratory of the twenty-first century. Nearly all of his central concepts can be observed in real time.
Start with the subordination of war to politics. Putin invaded Ukraine with a political objective that kept shifting as military reality contradicted it. The initial objective appears to have been the rapid collapse of the Zelensky government and its replacement with a regime friendly to Moscow. When that failed in the first weeks, the objective mutated into the capture of eastern and southern Ukraine. And when the Ukrainian counteroffensive of 2022 recovered Kherson and part of Kharkiv, the objective shrank further. The problem is that Putin’s political objectives were never articulated clearly, nor formally adjusted to the military reality. Clausewitz would have diagnosed this as the campaign’s original sin: launching a war without a precise definition of what would constitute an acceptable peace.
Friction is everywhere. The Russian offensive of February 2022 was a catalogue of frictions: armoured columns that ran out of fuel on the roads to Kyiv, unencrypted communications intercepted by the Ukrainians, units that did not know they were going to war until they crossed the border. Russian logistics, dependent on the railway and unable to sustain a road advance hundreds of kilometres from base, was the most visible manifestation of Clausewitzian friction at industrial scale. On the Ukrainian side, the 2023 counteroffensive ran into its own friction: Russian minefields of unprecedented density, lack of air superiority, and an offensive doctrine learned from NATO that could not be executed without NATO’s means.
The fog of war manifests in the difficulty of establishing even the most basic facts of the conflict. Russian casualty figures vary enormously depending on the source. The strategic intentions of both sides are inferred, not known. Public information is contaminated by propaganda from both parties and by the noise of social media. In a conflict where a TikTok video can have more impact than an intelligence briefing, the fog of war has not been dispelled by technology: it has thickened.
And the centre of gravity is the most debated question. What is Russia’s centre of gravity? Its army? Putin’s will? The Russian economy? What is Ukraine’s? Its army? Western support? If American and European backing is Ukraine’s true centre of gravity, then Russia’s strategy of dragging the war out until the West tires has an impeccable Clausewitzian logic. And if Putin’s will is Russia’s centre of gravity, then no Ukrainian battlefield victory resolves the war while Putin remains in power.
In the Middle East, the Clausewitzian logic operates differently but is equally visible. Israel possesses crushing military superiority over all its adversaries. But military superiority does not automatically translate into political victory. The ability to destroy Hamas as a military organisation does not amount to solving the political problem Hamas represents. Clausewitz would have observed that Israel wins wars but fails to achieve peace, precisely because the political objective, a stable resolution to the conflict, cannot be reached by exclusively military means. War is the continuation of politics, but when there is no politics, war spins in a void.
Why Military Strategists Still Study Him
On War is required reading at virtually every military academy in the Western world. West Point, Sandhurst, Saint-Cyr, the French École de Guerre, the German Führungsakademie. It is also studied in China and in Russia, where the Clausewitzian reading tradition runs deep. Lenin, who was no fool, read Clausewitz carefully and annotated On War extensively. Mao applied several of his principles, especially the primacy of the political over the military, in the Chinese revolutionary war.
The reason it continues to be studied is neither nostalgia nor institutional inertia. It is that Clausewitz offers something no other military theorist offers with the same depth: a framework for thinking about war that does not depend on technology. Sun Tzu is useful but aphoristic, more a collection of maxims than a theory. Jomini, Clausewitz’s contemporary and rival, offered a more systematic but more rigid vision, centred on geometric principles that modern war left behind. Clausewitz, by contrast, insisted that war is a phenomenon dominated by uncertainty, chance, and human passions, and that any theory attempting to reduce it to a fixed set of rules is doomed to fail.
This makes him particularly relevant at a moment when the technological temptation is enormous. Every new military technology, from the aeroplane to the nuclear missile, from the drone to artificial intelligence, generates a wave of predictions about how it will fundamentally transform war. Clausewitz is the antidote to that technological determinism. Technology changes the means, but it does not change the nature. War remains an act of violence to impose one’s will on the adversary, remains dominated by friction and uncertainty, and remains, in the final analysis, an instrument of politics.
Limits of the Doctrine in Asymmetric Wars
That said, Clausewitz has limits, and it is important to be honest about them.
The most evident is that Clausewitz conceived of war as a conflict between states. His model is the European interstate war: two governments, two armies, a defined battlefield, clear political objectives on both sides. This model describes the war between Russia and Ukraine well, describes Israel’s wars against its state adversaries reasonably well, but falls short when facing asymmetric warfare, insurgency, and terrorism.
When one of the belligerents is not a state but a decentralised network, like al-Qaeda or the Islamic State, the Clausewitzian trinity warps. Where is the government defining the political objective? Where is the army executing the campaign? Where is the people whose passion sustains the war? In an insurgency, all three functions blur. The guerrilla is simultaneously soldier, politician, and people. The centre of gravity is not an army that can be destroyed in battle but an idea that spreads, an identity that is defended, a network that reconstitutes itself every time it is cut.
The United States learned this the hard way in Iraq and Afghanistan. It won every conventional battle by overwhelming margins. It destroyed the Iraqi army in weeks, toppled the Taliban in months. And yet it lost both wars, or at least did not win them, because military victory did not produce the political peace that was sought. In Afghanistan, twenty years of occupation, a trillion dollars spent, and thousands of lives lost ended with the Taliban back in power, as though nothing had happened. Clausewitz would have diagnosed the problem precisely: the destruction of the enemy was confused with the achievement of the political objective. The battles were won and the war was lost.
Another limit is the nuclear question. Clausewitz spoke of the tendency of war to escalate towards extremes, what he called absolute war. In theory, the logic of war pushes towards the maximum application of force. In practice, politics limits that escalation. But in the nuclear age, escalation towards extremes has a literal meaning Clausewitz could not have imagined. Mutually assured destruction inverts the Clausewitzian logic: nuclear war cannot be the continuation of any politics because it leaves no politics to continue. The existence of nuclear weapons has created a category of conflict that escapes the Clausewitzian framework, or rather confirms it by negation: precisely because nuclear war can serve no rational political end, it functions as deterrence.
Politics and War: Inseparable
The most common error in reading Clausewitz is to interpret “war is the continuation of politics” as a cynical description of state behaviour. As if Clausewitz were saying that war is an acceptable instrument of policy, that it is fine to fight when diplomacy fails, that violence is simply another channel of negotiation. That is not what he says, or at least it is not all he says.
What Clausewitz says, and this is the truly profound point, is that war cannot be understood outside of politics. That war has no logic of its own. That every time a soldier or a politician tries to separate war from its political context, he commits an error that can prove fatal. MacArthur in Korea wanted to win the war regardless of the political consequences. Truman understood that war without political direction is a blind force. The American generals in Vietnam believed that with enough firepower they could win the war. They could not, because the war was not a military problem: it was a political problem that had no military solution.
This insistence on the primacy of the political is, paradoxically, Clausewitz’s most subversive idea. Because it implies that the ultimate responsibility for war falls on politicians, not on soldiers. It implies that a government launching a war without a clear political objective, without a definition of what constitutes an acceptable peace, without a strategy for moving from military victory to political stability, is not waging war: it is generating purposeless violence. It implies, too, that soldiers operating without clear political direction are condemned to win battles that resolve nothing.
There is a temptation, in a certain strand of contemporary thought, to believe that war is an anachronism, that global commerce, multilateral institutions, and economic interdependence have rendered it obsolete. This idea, attractive in the abstract, crashes against reality every few years. Ukraine, Gaza, the Sahel, Myanmar, Sudan. War has not disappeared. It has transformed, fragmented, grown more complex, but it is still there. And as long as it is still there, Clausewitz remains relevant.
Peace, as Clausewitz understood and as anyone with a realistic view of the world understands, is not the natural state of things. It is an achievement, fragile and temporary, sustained by the balance of power, by deterrence, and by the willingness of states to defend their interests. War is not the opposite of politics. It is its shadow. And whoever does not understand that understands neither war nor peace.
Clausewitz, a Prussian officer who died of cholera in 1831 without finishing his book, understood this better than most analysts writing today. Not because he was an abstract genius but because he spent twenty-two years on battlefields and learned, in the most direct way possible, that war is a human activity governed by politics, deformed by chance, and sustained by passion. That has not changed in two hundred years. It is not going to.