Among Carl von Clausewitz’s many poignant dictums, the most commonly cited is undoubtedly that “war is not merely an act of policy but a true political instrument, a continuation of political intercourse, carried on by other means.” While Clausewitz never fought in a city like Fallujah, Kyiv, or Gaza if the Prussian general and philosopher of war could visit the battlefields of the twenty-first century, he would recognize modern urban warfare’s core challenges—and would find that his theories about war’s objective and the considerations needed for victory remain strikingly relevant.

Clausewitz wrote that “war is more than a true chameleon that slightly adapts its characteristics to the given case.” Its essential elements—violence, chance and probability, and subordination to policy—form what he famously described as a wunderliche Dreifaltigkeit, or “remarkable trinity.” Rather than being in conflict, these elements interact dynamically and, in successful systems like that of Napoleonic France, can operate in harmony. Clausewitz and his fellow Prussian reformers admired how the French system aligned popular will, military force, and political direction. Nowhere is the need for such harmony more acute than in modern urban warfare, where civilians, combatants, and national objectives share the same congested terrain. This environment tests the limits of military doctrine, challenges the notion of strategic clarity, and often leaves combatants with ambiguous definitions of victory.

In my work on urban warfare, from my book Understanding Urban Warfare to the numerous case studies I have authored and the field research I have conducted, I’ve seen the truths Clausewitz described play out on concrete streets and in bombed-out buildings. Urban warfare has become the norm, not the exception, and Clausewitz’s insights are not relics of Napoleonic Europe—they are essential tools for understanding the future of conflict.

Historical Context: Urban Warfare in Clausewitz’s Era

While Clausewitz never commanded modern urban battles, his military career immersed him in conflicts where cities played central strategic and symbolic roles. As a young officer in the Prussian Army, he fought in the Rhine campaigns (1793–1794), including the siege of Mainz, where revolutionary France defended the city against a Prussian-Austrian coalition. This early exposure to urban siege warfare—marked by fortified positions, complex logistics, and the suffering of civilians—gave Clausewitz firsthand insight into the unique challenges of fighting in and around cities.

Clausewitz’s later experiences reinforced the political and psychological weight of urban centers. As aide-de-camp to Prussian Prince Augustus Ferdinand, he was present during Napoleon’s 1806 victory in the battles of Jena and Auerstedt, which led to the French occupation of Berlin. He later served with the Russian Army during France’s 1812 invasion of Russia, taking part in the Battle of Borodino—a prelude to the burning of Moscow that serves as a powerful example of a capital’s strategic and symbolic significance. In 1815, having reentered Prussian service, he participated in the Battles of Ligny and Wavre, fighting on terrain where towns, roads, and rivers constrained operations and shaped outcomes.

Clausewitz drew clear conclusions from these experiences. In Principles of War, he argued that “public opinion is won through great victories and the occupation of the enemy’s capital.” He understood cities not only as symbolic centers of national will but also as logistical and operational hubs, writing of the importance of targeting “principal cities, storehouses, and large fortresses.” Though he did not witness the dense, protracted urban warfare of the modern era, Clausewitz’s strategic emphasis on cities foreshadowed many of the dynamics seen in today’s urban battles.

The Urban Trinity, Fog, and Friction: Clausewitz’s Theories in Concrete and Steel

Clausewitz’s “remarkable trinity”—violence and hatred (the people), chance and probability (in military action), and reason and policy (the government)—finds its most visceral expression in urban warfare. Cities collapse these elements into a single, compact battlespace. Unlike operations in open terrain, urban warfare places civilians, combatants, and political objectives in constant, physical contact. The Clausewitzian trinity becomes spatially literal: civilians live among the fight, military action is hyperlocalized and constrained, and every movement carries political weight.

Clausewitz also famously wrote, “No one starts a war—or rather, no one in his senses ought to do so—without first being clear in his mind what he intends to achieve by that war and how he intends to conduct it.” He noted, therefore, that “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.”

This act of judgment is especially difficult in cities, where the kind of war one is fighting can shift from block to block. Is the objective to destroy an entrenched enemy force? To hold key, vital, or symbolic terrain? To safeguard a civilian population? In urban warfare the answer is often all of the above.

Clausewitz’s dictum that war is a continuation of politics by other means is vividly realized in urban combat. Tactical decisions in cities reverberate at strategic levels. Urban warfare does not allow separation between military action and political consequence—they are fused.

But Clausewitz reminds us that strategy is not made of battlefield maneuvers alone—it is also made of will. He defined war as “an act of force to compel our enemy to do our will.”

Victory, then, is not always the annihilation of enemy forces—it is the collapse of the enemy’s will to resist. And in modern urban warfare, maintaining the will of one’s own people (or of your ally’s population)—to support the fight or to accept the moral and political costs—is just as critical. Clausewitz considered these moral forces among the most decisive in war, writing that they “constitute the spirit that permeates war as a whole.” In cities under siege or attack, public opinion, national resolve, and leadership cohesion become as important as any tactical maneuver.

Urban warfare places enormous pressure on the internal willpower of a combatant nation and that of its involved and invested allies. The proximity of civilians, the visibility of destruction, and the speed at which information spreads can erode public support even as military objectives are met. A video, a collapsed building, or a failed operation can shift the strategic balance—not through force, but by weakening the political object that gives war its purpose. Clausewitz warned, “The political object is the goal, war is the means of reaching it, and means can never be considered in isolation from their purpose.”

This relationship between political objectives, military action, and national will is especially fragile in urban combat. When will breaks—on either side—the war may be lost regardless of battlefield gains.

Yet even the clearest strategy must contend with the inherent chaos of war. “War is the realm of uncertainty,” Clausewitz cautioned. “Three quarters of the factors on which action in war is based are wrapped in a fog of greater or lesser uncertainty.” This fog of war—its confusion, unpredictability, and lack of reliable information—is magnified in dense urban environments where lines between civilian and combatant blur and information spreads instantly and globally. Commanders must make high-stakes decisions in environments where clarity is fleeting.

Compounding this is what Clausewitz called friction—the accumulation of countless small obstacles that derail even the best-laid plans. As he wrote:

Everything in war is very simple, but the simplest thing is difficult. The difficulties accumulate and end by producing a kind of friction that is inconceivable unless one has experienced war. . . . Friction is the only concept that more or less corresponds to the factors that distinguish real war from war on paper.

Friction in cities is not theoretical—it’s tactical and visceral. Streets canalize movement. Buildings obscure lines of sight. Civilians become obstacles or allies. The environment itself resists clean execution. Urban warfare reveals Clausewitz’s insights not just as philosophical musings, but as hard realities in concrete and steel.

Urban Warfare in Iraq: Lessons from Baghdad and ISIS

The US campaigns in Iraq and the broader fight against the Islamic State of Iraq and Syria (ISIS) offer a laboratory of Clausewitzian warfare in cities—where tactical success frequently collided with political complexity, and where the will of the population, not battlefield metrics, often defined the limits of victory.

The 2003 “Thunder Run” into Baghdad was more than a demonstration of military power—it was a calculated strike at the enemy’s political center of gravity. Recall Clausewitz’s observation that “public opinion is won through great victories and the occupation of the enemy’s capital.” Taking Baghdad had immediate strategic effects: It overthrew Saddam Hussein and dismantled the Ba’athist regime. But it did not yield strategic clarity. Once the political objective shifted from regime removal to establishing a new political order—that is, nation-building—the occupation of the capital no longer compelled the enemy to do our will. Instead, it ushered in a new phase of resistance—fought not by conventional armies, but by insurgents embedded in the population. The Clausewitzian trinity fractured, and the fog of war deepened.

The 2004 First and Second Battles of Fallujah posed a different Clausewitzian challenge: how to reestablish control over a city that had become both a symbol and a stronghold of insurgent defiance. The battles exposed the full weight of friction. Every block was contested. Civilian presence, urban density, and improvised defenses neutralized many of the coalition’s technological advantages. Clausewitz’s observation rang true: The simplest thing became difficult. But beyond the tactical grind, Fallujah also heightened the strategic burden of fighting in cities under global media scrutiny. Images of destruction and civilian displacement reverberated internationally, influencing Iraqi public opinion, straining allied cohesion, and testing the will of the Iraqi government itself. Tactical brilliance could not guarantee strategic clarity—and each gain came at political and moral cost.

Clausewitz’s theories are no less relevant in the fight against ISIS. The battles for Mosul, Raqqa, and Aleppo offer vivid examples of Clausewitzian dynamics playing out in dense urban terrain.

The Battle of Mosul (2016–2017), the largest urban combat operation since World War II, marked both the height and unraveling of ISIS’s territorial control. The city—where ISIS declared its caliphate—was a living example of Clausewitz’s trinity: ideological violence among the people, unpredictable chance in military operations, and the overarching influence of policy and statecraft. ISIS weaponized the city’s geography to negate coalition advantages. Each alley and rooftop became a node of Clausewitzian friction, where the fog of war was compounded by hidden explosives, civilian shields, and the media theater of terror.

The struggle to recapture Raqqa (2017) similarly underscored Clausewitz’s emphasis on the strategic value of cities—but also on the cost of capturing them. Coalition forces had to balance the immediate tactical need for firepower with the long-term strategic imperative of minimizing civilian casualties and preserving infrastructure. Raqqa’s fall signaled not just military defeat for ISIS, but the collapse of its political narrative of governance and legitimacy.

Aleppo (2012–2016) offered a final case study in how urban warfare reshapes Clausewitzian dynamics. The regime of Bashar al-Assad, with Russian support, waged a prolonged campaign of attrition to reclaim the city. Aleppo’s recapture was not just a battlefield event—it was a strategic and psychological victory that reshaped the regional balance. Clausewitz’s insight that war is always shaped by the interaction of violence, politics, and chance was on full display. In Aleppo, military power served political ends—but at enormous humanitarian and reputational cost.

The Battle of Kyiv: A Clausewitzian Struggle

The 2022 Battle of Kyiv illustrates many of Clausewitz’s core principles. Russian forces launched a lightning assault on the capital, aiming to swiftly decapitate Ukraine’s political leadership and seize its strategic center of gravity. But what they encountered was not just a military defense, but a national resistance. The people, military, and government acted as one cohesive trinity. And President Volodymyr Zelenskyy’s decision to remain in Kyiv was not just political theater—it was a deliberate act of strategic will.

The defenders of Kyiv skillfully leveraged the urban environment to neutralize Russia’s advantages and impose costs at every level of engagement. What followed was a textbook display of Clausewitzian friction: stalled armored columns, logistical failures, intelligence breakdowns, and a general underestimation of local resistance. Citizen volunteers, guided by their knowledge of terrain and empowered by social networks, became a force multiplier against a numerically and technologically superior invader. Even simple tactical objectives—securing key intersections or resupplying units—became unexpectedly complex under the weight of terrain, resistance, and human error. This was the very essence of what Clausewitz warned distinguishes real war from war on paper.

Russia’s inability to capture the capital—the symbolic heart of the Ukrainian state—had cascading effects. It allowed Ukraine to garner international support, secure military resupply, and build momentum on the strategic level. In urban warfare, just holding out can be a victory. The defense of a city like Kyiv can serve not only to blunt an assault but to buy time for political conditions to shift, for alliances to strengthen, and for strategic clarity to emerge. In such contexts, endurance becomes its own form of offense.

This was not just a tactical defeat for Russia—it was a strategic failure born of a fundamental mismatch between political ambition and military means. The objective—seizing Kyiv—was politically clear, but Russia failed to align its resources, capabilities, and assumptions with that goal. Clausewitz’s admonition echoed loudly as Russian columns stalled short of the capital: “The political object is the goal, war is the means of reaching it, and means can never be considered in isolation from their purpose.” The Battle of Kyiv proved that even with overwhelming force, war conducted without coherence between ends and means is destined to fail.

Gaza and the Israel Defense Forces: Tactical Success, Strategic Strain

If Kyiv is a case study of Clausewitzian alignment of war and policy, Israel’s ongoing operations in Gaza provide another example of the dangers when the alignment falters.

The Israel Defense Forces are one of the most experienced militaries in urban warfare in the world. Israeli military operations are precise, intelligence-driven, and supported by technological superiority. Yet even these capabilities cannot eliminate the strategic dilemma of fighting in cities densely packed with civilians, under intense global scrutiny, and against nonstate actors that use the urban fabric—cities’ terrain and their people—as both shield and weapon.

Clausewitz emphasized that war is not an isolated act but part of a “continuous interaction”—including, notably, interaction with political objectives​. In Gaza, the Israel Defense Forces face a situation where the tactical destruction of enemy infrastructure—tunnels, command nodes, rocket sites—does not necessarily translate to strategic success of all the war’s political goals. Every collapsed apartment building and every civilian casualty reverberates globally. The moral forces Clausewitz emphasized—public opinion and will—are not abstract; they are measurable in diplomatic isolation or support, domestic cohesion, and battlefield morale.

This is not to say the Israeli military lacks clarity in its objectives, but rather that the urban environment imposes costs and constraints that can undermine strategic coherence. As I argued in Understanding Urban Warfare, a city can be the greatest ally or the worst foe, depending on how it is approached​. Clausewitz would remind any military leader that the means employed must remain proportionate and consistent with the political purpose.

Clausewitz also cautioned against rigid formulas. “Every age,” he wrote, “[has] had its own kind of war, its own limiting conditions, and its own peculiar preconceptions”.​ Urban warfare in the twenty-first century demands adaptation, and nowhere is this more evident than in the lessons derived from Gaza.

For the Israel Defense Forces operating in Gaza, every strike, pause, or maneuver is interpreted through political, humanitarian, and informational lenses. This is enhanced by the magnified friction of fighting in dense urban terrain. Streets can canalize movement, buildings and tunnels can conceal threats, and civilians can either support or sabotage operations.

Clausewitz, with his emphasis on uncertainty, chance, and moral forces, would have found urban warfare like that seen in Gaza to be the ultimate test of the statesman’s clarity and the commander’s judgment. In today’s information environment, that friction is amplified—a single video or narrative about the use (or misuse) of force, whether true or fabricated, can influence entire populations and political bodies. This aligns with Clausewitz’s trinity of wills—the people, the military, and the government, all three of which must be in balance for coherent strategy. In cities, that balance is constantly tested in real time and often in front of a global audience.

The Strategic Center of Gravity is Urban

Clausewitz’s concept of the “center of gravity”—the source of power that holds everything in war together—was one of his most important strategic insights. He described it as the “hub of all power and movement, on which everything depends.” In his time, contending military with the center of gravity often meant the destruction of the enemy’s main army or the occupation of its capital. But in modern warfare—especially in urban environments—the center of gravity is rarely a fixed physical point. It is dynamic, psychological, and deeply political.

Today, the center of gravity often resides in urban areas, not just as terrain to be seized but as spaces where power is concentrated: political authority, public opinion, information control, and the will of the people. Cities like Kyiv, Gaza City, Mosul, or Aleppo are not merely battlefields—they are arenas where military action collides with political meaning. Clausewitz would recognize these dynamics, because for him, the essence of war was not tactical victory but the pursuit of a political object shaped by what he called moral forces.

Again, Clausewitz wrote, “The moral elements are among the most important in war. They constitute the spirit that permeates war as a whole.” He was referring to intangible but decisive factors—public support, national will, leadership cohesion, and belief in the cause. These forces are especially visible in cities, where every strike and every image can either strengthen or fracture the political foundations of the war effort. What we might now call legitimacy in modern strategy—credibility in the eyes of a population or the international community—can be understood as the sum of these moral forces. Clausewitz didn’t use the term, but he clearly grasped its meaning and importance.

In Kyiv, the city itself became the center of gravity—not only for its political and logistical importance, but for what it symbolized. Its defense became an act of national will. In Gaza, the battle shifts between tactical objectives and a struggle over public opinion, both local and global.

In today’s urban conflicts, the political object—the goal, in Clausewitz’s terms, which must not be separated from war as the means of reaching it—is constantly under pressure. This pressure comes not just from the enemy, but also from how one’s own population, allies, and adversaries perceive the use of force. A commander may win the battle for terrain and still lose the war if public opinion collapses or the political object becomes unsustainable.

This is why the center of gravity in modern warfare often runs through the city—not because of what is physically located there, but because of what is at stake symbolically, psychologically, and politically. In cities, Clausewitz’s theory finds its sharpest edge: Moral forces meet material realities, and the balance of war can shift not through firepower alone, but through the will of those watching, enduring, or resisting.

Clausewitz in the Urban Century

Cities have become the default terrain of modern war. From Kyiv to Gaza, the battles fought today are not anomalies—they are signals. Urban warfare is not an exception to Clausewitz’s theory; it is its most vivid and volatile expression.

Cities compress all the elements Clausewitz identified as fundamental to war: violence, chance, political purpose, friction, and uncertainty. They bring the political object, the will of the people, and military action into immediate proximity—requiring a level of harmony among these forces that is difficult to achieve but critical to sustaining strategic coherence. In this space, tactical actions instantly reverberate across strategic and political spheres. Every strike is a message, every misstep a liability.

Clausewitz would demand that today’s commanders and policymakers understand that war in cities is not just about maneuver and firepower—it is about narrative, perception, endurance, and will. Modern urban warfare is fought in full view of the world, under moral scrutiny, and amid civilian populations whose support or suffering can shape the outcome as much as any weapon system.

Victory in this environment requires more than technological superiority. It demands clarity of purpose, coherence between means and ends, disciplined execution, and moral restraint—the very fundamentals Clausewitz insisted upon. These are not optional in the urban century. They are decisive.

Clausewitz offers no checklist for success in cities, but rather something more valuable. What he offers is a way to think clearly, to adapt amid chaos, and to confront the true nature of war—a contest of wills, shaped by politics, distorted by chance, and fought in the dense, contested, and morally fraught terrain of the modern city.

John Spencer is chair of urban warfare studies at the Modern War Institute, codirector of MWI’s Urban Warfare Project, and host of the Urban Warfare Project Podcast. He served twenty-five years as an infantry soldier, which included two combat tours in Iraq. He is the author of the book Connected Soldiers: Life, Leadership, and Social Connections in Modern War and coauthor of Understanding Urban Warfare.

The views expressed are those of the author and do not reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense.

Image credit: Staff Sgt. Jason Hull, US Army