Clausewitz, On War, Book V: Clausewitz on Combined Arms

Chapter Four of Book V of On War is titled “Relationship between the Branches of the Service.” This chapter, however, doesn’t really seek to explain the relationship between the branches (infantry, artillery, and cavalry). Instead, it seeks to explain the relative strengths and weaknesses of the three branches. The specific relationships between the branches are left for us to intuit.

Clausewitz explains the strengths right off:

“The engagement consists of two essentially different components: the destructive power of firearms, and hand-to-hand, or individual, combat. The latter in turn can be used for either attack or defense (words here employed in an absolute sense, for we are speaking in the broadest of terms). Artillery is effective only through the destructive power of fire; cavalry only by way of individual combat; infantry by both these means.

In hand-to-hand fighting, the essence of defense is to stand fast, as it were, rooted to the ground; whereas movement is the essence of attack. Cavalry is totally incapable of the former, but preeminent in the latter, so is suited only to attack. Infantry is best at standing fast, but does not lack some capacity to move.” (p.285)

Clausewitz then enumerates his thoughts on the combat arms:

“1. Infantry is the most independent of the arms.
2. Artillery has no independence.
3. When one or more arms are combined, infantry is the most important of them.
4. Cavalry is the most easily dispensable arm.
5. A combination of all three confers the greatest strength.” (p.286)

And so Clausewitz starts beating around the Combined Arms bush.

But what is Combined Arms?

Combined Arms is an approach to warfare which seeks to combine military arms to create complementary effects.

So Clausewitz recognizes that the combination of various combat arms can increase the effectiveness of the army (per #5 above.) But what does he say of the specific combination of arms? Is there a magic number of howitzers per 10,000 infantry? Apart from point #3 above, Clausewitz claims there might be a perfect proportion between the arms, but also claims that such a proportion is only theoretical:

“In theory, then, there is an optimum proportion between the arms, which in practice remains an unknown X, a mere figment of the imagination.” (p.287)

Clausewitz then goes on to explain the virtues and vices of artillery and cavalry, from which we can induce that Clausewitz views these arms as mere auxiliaries to the infantry, since he doesn’t discuss the virtues and vices of excessive amounts of infantry (i.e. Clausewitz views infantry is the core combat arm.)

Clausewitz also tackles the question of what happens to the nature of a given conflict when there is a preponderance of a given arm. In short, an excess of guns imposes a rather static battlefield and attritionist tactics. A shortage of artillery restores movement to the battlefield.

A prevalence of cavalry allows for sweeping attacks on flanks and the rear, while conferring the ability to keep the enemy at a distance. A lack of cavalry forces the armies to fight in closer contact.

As the combat arms affect the nature of the war, so the nature of the war affects the combat arms. He allows that in People’s War (what we would call irregular war, rebellion, or insurgency) the main arm is the infantry to an extent even larger than conventional warfare. (p.288.)

Clausewitz completes his chapter with a summary of his conclusions:

“1. Infantry is the main branch of 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 the 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.” (p.291)

Let us now evaluate Clausewitz’s conception of combined arms.

Clausewitz has fairly modern view of combined arms. While recognizing the supremacy of infantry in almost all ground combat operations, he allows for strengthening the army using auxiliary forces of other arms. He recognized that various situations might call for different proportions of arms. He didn’t jump on any bandwagon which advocated the supremacy of the howitzer or the saber. For this he should be commended.

However…

He espouses an awareness of the different strengths of the three branches, yet fails to delve into the relationships between the branches. For example, he makes no mention of who is responsible for furnishing support to whom.

Nor does Clausewitz speak of the types of support that are advantageous for a given situation. For example, is artillery support advisable in an infantry or cavalry attack? What sorts of support? Should enemy positions be “softened” by preparatory fires? Or might those preparatory fires only telegraph intentions? If cavalry is so superior in the attack, what might we do to such an attack if we only have infantry and artillery to oppose such an attack? When is cavalry better utilizes for reconnaissance, and when it is best used for the attack? These are crucial tactical questions that Clausewitz failed to answer.

Clausewitz also fails to identify any sort of combined arms relationships between units below the brigade level. In all seriousness, Clausewitz cannot really be blamed for this. He was a man of his time, when homogeneous regiments of a given arm were raised and subordinated to the corps, division or brigade. Combined-arms battalions, companies, platoons, and detachments were unknown. In fact, platoons didn’t even exist as tactical units until much after Clausewitz’s time. Yet there is nothing which would have prevented specialized combined-arms task forces from being employed in Clausewitz’s time, and his failure to define such a proposition can be viewed as a deficiency.

That said, it is worth noting that modern combined-arms doctrine has reached practical apogee. Combined arms doctrine now permeates virtually all military doctrine and forces. In the United States, combined arms doctrine exists from the fireteam level, where hand grenades complement rifles, through all levels of combat to the nuclear-strategic level, where the triad of nuclear missiles, nuclear submarines, and bomber aircraft complement one another in furnishing the nuclear deterrent. Yet this combined-arms thinking is not only found in modern conventional and nuclear forces. In Israel’s 2006 war against Hizbollah, Hizbollah managed to fight the Israeli Defense Forces to a standstill using a combined-arms potion of anti-tank guided missiles, irregular partisans, and propaganda distributed by the Internet and media.

It must be stated that Clausewitz is very generous to the artillery when describing their destructive power. 18th century cannon, as well as 21st century howitzers and mortars, are formidable weapons, but their destructive capability is greatly overstated. Their worth lies in their suppressive capabilities—they keep the enemy from firing, maneuvering, or otherwise undertaking whatever tasks he wishes. This is crucial to recognize, as any time you are using artillery fires to destroy something, odds are that it is a misapplication of fires. Any additional fires beyond what is required to suppress the enemy are probably wasted. This also implies that there is probably an upper limit to the amount of artillery in a given force for a given situation, and that limit is not defined by material circumstances, wealth, or numbers of men. It is instead defined by the point of diminishing returns.

How does the Clausewitzian concept of Combined Arms translate to warfare today?

First, it should be noted that the three branches of service that Clausewitz names are utterly archaic today. Modern infantry exists in myriad forms. The standard, basic infantry is actually quite rare in modern armies. In most conventional armies, infantries are found in various forms: mechanized, motorized, heliborne, airborne, Marine, mountain, Ranger, and Special Forces. The modern infantries are instead given various degrees of enhanced speed, maneuverability, armor protection. Modern infantry has more mobility than cavalry, and often employs more firepower than artillery.

Cavalry, despite Corb Lund’s singing, is unreservedly dead as a modern combat arm. Though some units may claim lineage to the cavalry of older times, these units are almost always actually mechanized or aviation units. One modern type of cavalry is the Armored Cavalry Regiment, which contain mechanized infantry, tanks, artillery, and aviation all under the command of a colonel. Yet the ACR is capable of both attack and defense, and can deliver much more firepower than even artillery units of yore.

Artillery, preeminent in firepower, is no longer as dependent on infantry for protection, nor is it as immobile as it used to be. Modern artillery ranges from the mortars that are organic to infantry companies and battalion, through modern towed howitzers, to self–propelled artillery. Modern artillery is mobile, is capable of high rates of fire, and is capable of delivering a whole range of effects from delivering smoke obscurants and mines to specialized laser-guided cluster-bomblet rounds. Some modern self-propelled artillery pieces resemble tanks in their mobility, and some mortars can be carried by a single man, and are well-employed by handful of men.

The branches Clausewitz worked with have therefore been blurred together when considering their capabilities. But this is not to say that the branches have merged. Modern artillery might be highly mobile, but it still excels at providing only suppressive fires. Infantry has extreme mobility, but is now charged with destroying the enemy. And the modern equivalents of cavalry (tanks, light-armored vehicles, and aviation) still require coordination with the infantry to provide protection (in the case of tanks), and to coordinate fires (in the case of aviation). The branches have blurred in terms of capability, but they are still very separate in their functions. Combined Arms fighting is as crucial today as ever.

Something needs to be stated on the moral aspect of combined arms. Moral strength can be derived from the orchestration of the arms, and that moral strength can be translated into success. I last fought in Iraq in 2006, and during that time I traveled by way of convoy at a time when the roadside bomb and the ambush were the main source of Coalition casualties. Therefore we arranged a section of AH-1W Cobras to provide aerial escort to the convoy. Those two aircraft and the four Marines manning them never did have to fire their weapons, almost certainly because their very presence deterred any action against my ground convoy. We were able to essentially drive on enemy-infested roads without fear, and that lack of fear reinforces moral strength.

Yet the moral strength of combined arms can also work against the stronger side when fighting in an asymmetric war. This is particularly true in cases where the weaker makes use of an aggressive media strategy. The Israelis learned this lesson the hard way, in the so-called Jenin Massacre, and in the 2006 Lebanon War. Bottom line, to a neutral bystander, the sight of combined arms fighting is terrifying, and the side that uses combined arms in plain sight of the media only welcomes losing support in the court of opinion.

In conclusion, Clausewitz was generally correct when it comes to combined arms, but his precepts were designed for the 19th century. Some of his thoughts can be transported to the 21st century with modification, but only with caution. The ubiquity of media and the prevalence of irregular conflict in modern times are factors that Clausewitz did not take accounting for. Consequently, the onus is on us to bring inject creativity into our military operations, so that victory may be attained with low human and material costs.