Clausewitz and The Infantry Problem

Does the Prussian Offer a Solution?

Prussians Attack Plancenoit, painting by Adolf Norther

I wrote an article about a year ago titled “The Infantry Problem,” which explored the enduring challenge militaries face in sustaining the most important soldier on the battlefield: the infantryman. Despite technological advances and evolving doctrines, the fundamental dilemma of raising, training, equipping, organizing, and supporting large numbers of infantry persists as a central concern in military affairs. Infantry are not only the most numerous and vulnerable soldiers but also the most indispensable, as they directly bear the brunt of combat and are key to achieving tactical and strategic objectives. But what does the great philosopher of war, Carl von Clausewitz, have to say about this? Does he offer practical solutions to the infantry problem, or, like many before and since, ultimately confounded by a challenge that continues to haunt military organizations?

For the uninitiated, Carl von Clausewitz (1780–1831) was a Prussian general and one of the most influential military theorists in history, best known for his seminal work, On War (Vom Kriege).¹ A veteran of the Napoleonic Wars, Clausewitz drew on his combat experience and deep study of military history to analyze the nature of war, famously describing it as “a continuation of political intercourse, carried on with other means.”² He was a ferocious writer; On War and the compilation of his work in Historical and Political Writings totals more than 1000 pages. This is in addition to hundreds of pages of correspondence, letters, and memos he wrote throughout his career so there is plentiful material to choose from. His ideas explored the complex interplay of chance, friction, and human will on the battlefield, emphasizing that war could never be reduced to simple formulas.³ Clausewitz’s insights into strategy, the importance of moral forces, and the need to align military operations with political objectives have shaped military thought for nearly two centuries, making him a foundational figure in both historical and contemporary strategic studies.

The man himself.

However, it should be noted there is Clausewitz, and there is “Clausewitz.”⁴ Clausewitz perhaps more than any other western military theorist is more often quoted than actually read. Because On War was not fully finished and he planned to add revisions, historians and analysts have been speculating ever since about what he would have written further or what his original meaning was. Consequently, debates over the correct reading of key concepts, such as the nature of the “culminating point,” the meaning of “absolute war,” the “center of gravity,” or his famous dictum that war is “the continuation of politics by other means,” have become almost a scholarly discipline in their own right.⁵ For example, the British historian and former army officer B. H. Liddell Hart famously mischaracterized Clausewitz as the “Mahdi of Mass,” the “apostle of total war,” the “evil genius of military thought,” the man whose “gospel” had been “accepted everywhere as true” and who was supposedly directly responsible for the pointless carnage of World War I for which many scholars have spent years pushing back against.⁶ This specialized field not only seeks to clarify Clausewitz’s original intent but also examines how his theories have been appropriated, misused, or oversimplified in military, political, and academic circles across different eras and cultures.⁷

Scholars in this area meticulously examine what Clausewitz actually intended to convey, as opposed to what has been mistakenly attributed to him over the years.⁸ Because his prose is dense, often ambiguous, and originally written in early 19th-century German, even subtle errors in translation or context can lead to significant distortions of his ideas. These misunderstandings have, at times, resulted in Clausewitz’s work being co-opted to support strategic concepts he would never have endorsed or to justify doctrines fundamentally at odds with his theory of war.⁹ Thus, any attempt to grapple with the enduring infantry problem, or any other aspect of war, must begin with a careful reading of Clausewitz himself, lest we mistake the shadow of his ideas for the substance and risk drawing flawed lessons from one of history’s most profound thinkers on the art of war.

Die Tafelrunde (The Roundtable), by Josef Schneider. Clausewitz is seated to the left.

For the purposes of this essay, “the infantry problem” refers to the enduring challenge of raising, training, equipping, organizing, and sustaining large numbers of infantry soldiers while recognizing their extreme vulnerability on the battlefield.¹⁰ Clausewitz doesn’t outright identify or define the infantry problem, at least not exactly in the authors definition, but he readily identifies and writes about many aspects of it in On War and his other work.¹¹ He repeatedly addresses the immense demands placed on states to prepare and maintain effective infantry forces, the logistical burdens required to keep them operational in the field, and the devastating losses they can suffer in battle. His observations on the complexities of recruitment, training, provisioning, and the coordination of infantry with other arms reveal his acute awareness of the problem, even if he never labeled it as such. Through his analysis, Clausewitz provides a rich foundation for understanding why the infantry problem remains a central dilemma for military organizations past and present.

Clausewitz asserts the primacy of the infantry in Book Five, Chapter Four in On War stating:

An army composed simply of artillery, therefore, would be absurd in war. An army consisting simply of cavalry is conceivable, but would have little strength in depth. An army consisting simply of infantry is not only conceivable, but would be a great deal stronger. The degree of independence of the three branches, then, is infantry, cavalry, artillery.¹²

He also wrote, “Artillery is effective only through the destructive power of fire; cavalry only by way of individual combat; infantry by both these means.”¹³ Finally, he listed that the “Infantry is the most independent of the arms” and “when one or more of the arms are combined, infantry is the most important of them.”¹⁴ That Clausewitz recognized the infantry as the main cog in the machine is unsurprising. The Napoleonic Wars were an infantryman’s war; one could not do much of anything without a large number of men armed with a musket and bayonet. However, he still wrote that, “Granted that infantry is the most versatile and indispensable of the arms, one nevertheless also has need for artillery and cavalry.”¹⁵ In other words, infantry could survive on its own, but actual military strength lay in the effective integration and coordination of all three branches.

For Clausewitz, the branches of the military service and their respective relationships were essentially two parts of an equation. One part concerned the number of soldiers in each branch, along with their level of training and the quality of their equipment. The other part involved calculating the costs and the logistical effort required to raise, maintain, and deploy these forces effectively. He wrote, “If one could compare the cost of raising and maintaining the various arms with the service each performs in time of war, one would end up with a definite figure which would express the optimum equation in abstract terms.”¹⁶ However, this is a classic case of “friction” as he surmised that trying to calculate a “systems” or “cost-effectiveness” analysis were “hardly more than a guessing game.”¹⁷ Sure, estimating the cost to build a cannon or pay a soldier was relatively easy, they were a “purely monetary factor,” but how could one calculate the cost of human life or the costs that would be incurred during a military campaign which were unpredictable, based on luck, and full of chance?¹⁸ Even if one could fully solve the equation, would the army that emerged be able to achieve the military and political “objects” of the war in question? This question prompted Clausewitz to write,

The peculiarities that arise from the predominance of one particular arm are the more relevant to the art of war in the narrower sense, since it is concerned with the use of available forces. These are usually assigned to the commander in proportion to their availability without his having much say in the matter.¹⁹

This doesn’t mean one should disregard the costs of an army and its infantry; as Clausewitz wrote, “it is possible to calculate what would happen if one arm were greatly superior or inferior to the same arm on the other side.”²⁰ Yet in practice, the ideal distribution of arms is rarely achieved, and commanders must remain flexible, ready to exploit advantages and compensate for shortcomings inherent in the composition of their forces. When one branch, whether infantry, cavalry, or artillery, predominates, it brings with it particular strengths and vulnerabilities that fundamentally shape what a commander can realistically accomplish on the battlefield. Still, none of this can be executed without the infantry, which, during the Napoleonic Wars, had expanded dramatically due to the widespread adoption of firearms and mass mobilization.²¹

This all leads to Clausewitz’s classic observation, “everything in war is very simple, but the simplest thing is difficult.”²² To transform a regular civilian into a capable infantryman, a lengthy and meticulous process must first unfold.²³ Recruitment is the essential starting point, identifying and enlisting men willing or compelled to serve. Once recruited, each soldier undergoes rigorous individual training, learning the fundamentals of drill, discipline, weapon handling, and personal combat skills. Equipping the infantryman with the appropriate uniforms, muskets, bayonets, ammunition, and other necessary gear ensures he is materially prepared for the battlefield's demands. However, individual competence alone is insufficient; the soldier must then be integrated into a larger formation, where he trains alongside his comrades in the complexities of unit maneuvers, coordinated marching, formation changes, and synchronized volley fire, skills vital for the collective effectiveness of an infantry company or battalion.

All these stages, recruitment, individual training, equipping, and unit integration, must be accomplished before a campaign can even begin. Once in the field, the infantryman must be continually provisioned with food, ammunition, clothing, and medical support to remain operational, creating a massive logistical burden for any army. Yet, despite the months or even years of preparation, time, and resources invested, the life of an infantryman is extraordinarily fragile: a single musket ball or a shard of canister shot from an enemy cannon can end his service, and life, in mere seconds.

Clausewitz concludes Book Five with a summary of his thoughts identifying the infantry as the most essential branch of the armed services;

1. Infantry is the main branch of the service; the other two are supplementary.

2. A high degree of skill and vigor in the conduct of war can to some extent make up for a lack of the supplementary branches—assuming great numerical superiority in infantry. The higher the quality of the infantry, the easier this will be.

3. It is harder to do without artillery than without cavalry: artillery is the principal agent of destruction, and its use in action is more closely coordinated with the infantry’s.

4. In general, artillery being the strongest agent of destruction and cavalry the weakest, one is always confronted with the question of how much artillery one can have without it being a disadvantage, and with how little cavalry one can manage.²⁴

Clausewitz’s repeated emphasis on infantry as the main and most indispensable branch of the armed services reveals his acute understanding of what we now call the infantry problem. By clearly stating that an army made up solely of artillery would be absurd, that an army of only cavalry would lack depth, but that an infantry-based army would still be fundamentally strong, Clausewitz highlights the singular importance of massed, well-trained foot soldiers to the success of any military endeavor. His discussion of the difficulties inherent in determining the optimal balance among infantry, artillery, and cavalry further exposes the complex calculations required to sustain a capable infantry force without undermining the overall effectiveness of the army. Moreover, his acknowledgment of the immense effort needed to raise, equip, train, and maintain infantry, and the devastating losses they inevitably suffer through his description of battle, demonstrates that Clausewitz did not merely consider infantry vital in an abstract sense. Instead, he recognized that the infantry’s primacy lay at the heart of the persistent and painful challenge every state faces in waging war: how to field enough capable soldiers, maintain their combat effectiveness, and endure the high human and logistical costs of infantry-centric warfare, a phenomenon that has not stopped in 2025.

Prussian soldiers in various unforms during the Napoleonic era.

Clausewitz very readily identifies many aspects of the infantry problem but does he offer a solution? Clausewitz very early recognized that the French Revolution and Napoleon had unleased a new type of war that he called “people’s war,” writing, “War was returned to the people, who to some extent had been separated from it by the professional standing armies; war cast off its shackles and crossed the bounds of what had once seemed possible.”²⁵ Clausewitz advocated for mass mobilization of manpower through systems like the Landwehr, emphasizing the importance of harnessing the full manpower potential of the nation to raise large numbers of soldiers and replenish losses, a pragmatic approach that recognized the realities of attrition and the need for depth in infantry ranks. He also emphasized the importance of thorough preparation, efficient supply systems, and meticulous campaign planning to minimize unnecessary losses, as evident in his criticism of Napoleon’s disastrous 1812 invasion of Russia.

However, in other respects, Clausewitz does not provide a definitive answer, largely because On War, the primary text examined in this essay, is a theory of war, rather than an operational manual.²⁶ It is intended to offer a conceptual framework for understanding the nature and dynamics of war, rather than prescribing specific doctrines or tactical solutions. He repeatedly acknowledges the inherent unpredictability of war, what he famously called “friction,” and the impossibility of fully solving the “optimum equation” of balancing costs, force composition, and effectiveness. Even with the best preparation, he argues, chance and uncertainty will always disrupt plans, and no formula can guarantee the success or survival of infantry forces. This ambiguity reflects Clausewitz’s larger philosophy: rather than offering simple solutions, he invites commanders and statesmen to think critically about problems, including the infantry problem, and adapt to its challenges with a flexible, realistic mindset, accepting that some aspects of the problem can only be managed, never entirely solved.

Additionally, compared to many of his other theses, his idea of people’s war was met with hostility by some of the Prussian military establishment because, in their view, it would degrade the professionalism of the military. Nonetheless, the Landwehr system is largely how Prussia was able to mobilize 5% of their population during the War of the 6th Coalition with the army peaking at some 275,000 soldiers in the fall of 1813.²⁷ After the Napoleonic Wars, the victorious monarchs attempted put the “genie of nationalism and it’s concomitant people’s war back in the bottle” as one historian put it.²⁸ Thus, Clausewitz’s emphasis on infantry and mass mobilization became less prominent in the decades following his death. Yet he remained a touchstone for some military thinkers, including Sigismund von Schlichting, a prominent commander during the German Wars of Unification. In his 1880s article “On the Infantry Battle,” Schlichting invoked Clausewitz’s observation that the defensive form of war is inherently stronger than the offensive.²⁹ He used this point to reinforce his own argument that the advent of modern infantry weapons—particularly rapid-firing rifles and more accurate artillery—had made offensive operations even more difficult and costly, further tipping the balance in favor of the defender.³⁰

But it is also worth examining the broader nature of the Napoleonic Wars themselves. While armies grew to unprecedented sizes and battles became increasingly bloody, direct combat was often not the primary cause of casualties. Instead, disease, exhaustion, exposure, desertion, and other non-battle factors claimed far more lives than musket balls or cannon fire. Marches over vast distances with inadequate sanitation and supply systems led to outbreaks of dysentery, typhus, and other deadly illnesses that could decimate entire regiments long before they reached the battlefield. Poor nutrition, lack of clean water, and the physical toll of continuous campaigning further weakened soldiers, making them more vulnerable to disease and reducing the combat effectiveness of armies. For example, Clausewitz believed that Napoleon could have reached Moscow with more than 200,000 instead of 90,000 if he had,

A more thorough preparation for the campaign, better organization of his supply services, and more carefully planned marches to avoid bringing together such huge masses of men on a single road would have prevented the shortages that prevailed from the beginning and would have limited the army's losses.³¹

Clausewitz dedicates seven chapters in On War to the subjects of marching, supply bases, and lines of communication, an emphasis that underscores his understanding of the logistical underpinnings of military success. For Clausewitz, these were not secondary technical matters but integral components of strategy itself. An army's ability to move effectively, sustain itself over long distances, and maintain secure lines of communication with its base of operations was as decisive as its performance in battle. Poorly coordinated marches could exhaust troops before they ever met the enemy; disorganized supply lines could bring entire campaigns to a standstill; and inadequate planning could expose forces to unnecessary attrition, disease, and demoralization. By devoting sustained attention to these logistical realities, Clausewitz reveals his broader philosophy: that war is not won solely through tactical brilliance or battlefield heroism, but through the careful orchestration of movement, supply, and endurance over time. In this view, solving the infantry problem meant mastering not only combat but also the conditions that enable infantry to survive long enough to fight.

Clausewitz includes a chapter titled “Superiority of Numbers” in Book Three of On War, where he plainly states, “superiority of numbers is the most common element in victory.”³² Although he does not explicitly specify that this numerical superiority must come from greater numbers of infantry, the broader context of his work, and what is discussed above in this essay, makes it clear that he saw infantry as the primary source of mass on the battlefield. Firepower in the form of artillery could mask the quality or numbers of infantry; he wrote, “increase in artillery is certainly the fastest means of bolstering its forces and bringing about some sort of balance.”³³ But there came a point when artillery in large numbers would limit an army’s mobility and require even more infantry “since in itself it is unable to engage in hand-to-hand combat.”³⁴ Thus again, the infantry reigns supreme.

Clausewitz doesn’t offer a secret solution to the infantry problem, but acknowledging the problem and stating the obvious might be good enough, given how often military organizations throughout history have neglected the infantry. By emphasizing the need for thorough preparation, the ability to mobilize national manpower, and the recognition that war cannot be reduced to mechanical calculations, Clausewitz compels leaders to confront the harsh realities of sustaining effective infantry forces. His writings remind us that the strength of an army rests not in grand theories or technological shortcuts but in the quality, resilience, and support of its foot soldiers. In this way, Clausewitz’s enduring value lies less in prescribing easy answers and more in forcing military and political leaders to face the fundamental, unchanging truth that victory in war depends on the ability to raise, train, and maintain the infantry, the indispensable backbone of any army, despite the immense costs and inevitable uncertainties involved.

1.

Kiran Pfitzner

has an entire substack dedicated to the great Prussian which I highly recommend.

2. Carl von Clausewitz, On War, trans. Michael Howard and Peter Paret (Princeton: Princeton University Press, 1984), 87.

3. Alan Beyerchen, “Clausewitz, Nonlinearity, and the Unpredictability of War.” International Security 17, no. 3 (1992): 59–90.

4. Highly recommend this essay by

B. A. Friedman

who gives a good overview of the issues with Clausewitz, What to do about "Clausewitz".

5. His work also really did not make it beyond Prussia until the early 1900’s when historians and military officers began to read his work seriously in Great Britain and the United States, see Christopher Bassford, Clausewitz in English: The Reception of Clausewitz in Britain and America, 1815–1945, 1st ed. (Oxford: Oxford University Press, 1994).

6. Christopher Bassford, “John Keegan and the Grand Tradition of Trashing Clausewitz: A Polemic.” War in History 1, no. 3 (1994): 319.

7. For the problems with Clausewitz interpretations in Great Britain and the United States, see Christopher Bassford, Clausewitz in English: The Reception of Clausewitz in Britain and America, 1815–1945, 1st ed. (Oxford: Oxford University Press, 1994).

8. Bassford, 319–36.

9. For example, see debate over the influence of Clausewitz over the U.S. Military, Phillip S. Meilinger, “Busting the Icon: Restoring Balance to the Influence of Clausewitz.” Strategic Studies Quarterly 1, no. 1 (2007): 116–45. The counterargument, Nikolas Gardner, “Resurrecting the ‘Icon’: The Enduring Relevance of Clausewitz’s On War.” Strategic Studies Quarterly 3, no. 1 (2009): 119–33.

10. See Again, “The Infantry Problem.”

11. The word infantry shows up 60 plus times in On War.

12. Clausewitz, On War, 285.

13. Clausewitz, On War, 285.

14. Clausewitz, On War, 285. Number points 1 and 3.

15. Clausewitz, On War, 291.

16. Clausewitz, On War, 673.

17. Clausewitz, On War, 286. Brodie uses the terms “systems” and “cost effectiveness,” 672.

18. Clausewitz, On War, 286.

19. Clausewitz, On War, 286.

20. Clausewitz, On War, 287-289.

21. Clausewitz, On War, 95. Mass mobilization or “people’s war” is discussed later in the essay.

22. Clausewitz, On War, 286.

23. Clausewitz doesn’t lay out all this but he does discuss “physical effort in war,” On War, 115-116.

24. Carl von Clausewitz, Historical and Political Writings, ed. and trans. Peter Paret and Daniel Moran (Princeton, NJ: Princeton University Press, 1992), 76.

25. Clausewitz, Historical and Political Writings, 287.

26. Peter Paret, “Clausewitz and the Nineteenth Century,” in Michael Howard, ed., The Theory and Practice of War: Essays Presented to Captain B. H. Liddell Hart (New York: Praeger, 1965), 31

27. Michael V. Leggiere, Napoleon and the Struggle for Germany: The Franco-Prussian War of 1813. Vol. 2 of Cambridge Military Histories (Cambridge: Cambridge University Press, 2015), 91.

28. Robert T. Foley, German Strategy and the Path to Verdun: Erich von Falkenhayn and the Development of Attrition, 1870–1916 (Cambridge: Cambridge University Press, 2005), 14.

29. Antulio J. Echevarria II, “Borrowing from the Master: Uses of Clausewitz in German Military Literature Before the Great War,” War in History 3, no. 3 (July 1996): 281.

30. Ibid., 282.

31. Clausewitz, On War, 194.

32. Clausewitz, On War, 288.

33. Clausewitz, On War, 287.

34. Clausewitz, Historical and Political Writings, 202.