Tag Carl von Clausewitz

Force Ratios in Conventional Combat

American soldiers of the 117th Infantry Regiment, Tennessee National Guard, part of the 30th Infantry Division, move past a destroyed American M5A1 “Stuart” tank on their march to recapture the town of St. Vith during the Battle of the Bulge, January 1945. [Wikipedia]
[This piece was originally posted on 16 May 2017.]

This post is a partial response to questions from one of our readers (Stilzkin). On the subject of force ratios in conventional combat….I know of no detailed discussion on the phenomenon published to date. It was clearly addressed by Clausewitz. For example:

At Leuthen Frederick the Great, with about 30,000 men, defeated 80,000 Austrians; at Rossbach he defeated 50,000 allies with 25,000 men. These however are the only examples of victories over an opponent two or even nearly three times as strong. Charles XII at the battle of Narva is not in the same category. The Russian at that time could hardly be considered as Europeans; moreover, we know too little about the main features of that battle. Bonaparte commanded 120,000 men at Dresden against 220,000—not quite half. At Kolin, Frederick the Great’s 30,000 men could not defeat 50,000 Austrians; similarly, victory eluded Bonaparte at the desperate battle of Leipzig, though with his 160,000 men against 280,000, his opponent was far from being twice as strong.

These examples may show that in modern Europe even the most talented general will find it very difficult to defeat an opponent twice his strength. When we observe that the skill of the greatest commanders may be counterbalanced by a two-to-one ratio in the fighting forces, we cannot doubt that superiority in numbers (it does not have to more than double) will suffice to assure victory, however adverse the other circumstances.

and:

If we thus strip the engagement of all the variables arising from its purpose and circumstance, and disregard the fighting value of the troops involved (which is a given quantity), we are left with the bare concept of the engagement, a shapeless battle in which the only distinguishing factors is the number of troops on either side.

These numbers, therefore, will determine victory. It is, of course, evident from the mass of abstractions I have made to reach this point that superiority of numbers in a given engagement is only one of the factors that determines victory. Superior numbers, far from contributing everything, or even a substantial part, to victory, may actually be contributing very little, depending on the circumstances.

But superiority varies in degree. It can be two to one, or three or four to one, and so on; it can obviously reach the point where it is overwhelming.

In this sense superiority of numbers admittedly is the most important factor in the outcome of an engagement, as long as it is great enough to counterbalance all other contributing circumstance. It thus follows that as many troops as possible should be brought into the engagement at the decisive point.

And, in relation to making a combat model:

Numerical superiority was a material factor. It was chosen from all elements that make up victory because, by using combinations of time and space, it could be fitted into a mathematical system of laws. It was thought that all other factors could be ignored if they were assumed to be equal on both sides and thus cancelled one another out. That might have been acceptable as a temporary device for the study of the characteristics of this single factor; but to make the device permanent, to accept superiority of numbers as the one and only rule, and to reduce the whole secret of the art of war to a formula of numerical superiority at a certain time and a certain place was an oversimplification that would not have stood up for a moment against the realities of life.

Force ratios were discussed in various versions of FM 105-5 Maneuver Control, but as far as I can tell, this was not material analytically developed. It was a set of rules, pulled together by a group of anonymous writers for the sake of being able to adjudicate wargames.

The only detailed quantification of force ratios was provided in Numbers, Predictions and War by Trevor Dupuy. Again, these were modeling constructs, not something that was analytically developed (although there was significant background research done and the model was validated multiple times). He then discusses the subject in his book Understanding War, which I consider the most significant book of the 90+ that he wrote or co-authored.

The only analytically based discussion of force ratios that I am aware of (or at least can think of at this moment) is my discussion in my upcoming book War by Numbers: Understanding Conventional Combat. It is the second chapter of the book: https://dupuyinstitute.org/2016/02/17/war-by-numbers-iii/

In this book, I assembled the force ratios required to win a battle based upon a large number of cases from World War II division-level combat. For example (page 18 of the manuscript):

I did this for the ETO, for the battles of Kharkov and Kursk (Eastern Front 1943, divided by when the Germans are attacking and when the Soviets are attacking) and for PTO (Manila and Okinawa 1945).

There is more than can be done on this, and we do have the data assembled to do this, but as always, I have not gotten around to it. This is why I am already considering a War by Numbers II, as I am already thinking about all the subjects I did not cover in sufficient depth in my first book.

Dupuy’s Verities: The Utility Of Defense

Battle of Franklin, 1864 by Kurz and Allison. Restoration by Adam Cuerden [Wikimedia Commons]

The third of Trevor Dupuy’s Timeless Verities of Combat is:

Defensive posture is necessary when successful offense is impossible.

From Understanding War (1987):

Even though offensive action is essential to ultimate combat success, a combat commander opposed by a more powerful enemy has no choice but to assume a defensive posture. Since defensive posture automatically increases the combat power of his force, the defending commander at least partially redresses the imbalance of forces. At a minimum he is able to slow down the advance of the attacking enemy, and he might even beat him. In this way, through negative combat results, the defender may ultimately hope to wear down the attacker to the extent that his initial relative weakness is transformed into relative superiority, thus offering the possibility of eventually assuming the offensive and achieving positive combat results. The Franklin and Nashville Campaign of our Civil War, and the El Alamein Campaign of World War II are examples.

Sometimes the commander of a numerically superior offensive force may reduce the strength of portions of his force in order to achieve decisive superiority for maximum impact on the enemy at some other critical point on the battlefield, with the result that those reduced-strength components are locally outnumbered. A contingent thus reduced in strength may therefore be required to assume a defensive posture, even though the overall operational posture of the marginally superior force is offensive, and the strengthened contingent of the same force is attacking with the advantage of superior combat power. A classic example was the role of Davout at Auerstadt when Napoléon was crushing the Prussians at Jena. Another is the role played by “Stonewall” Jackson’s corps at the Second Battle of Bull Run. [pp. 2-3]

This verity is both derivative of Dupuy’s belief that the defensive posture is a human reaction to the lethal environment of combat, and his concurrence with Clausewitz’s dictum that the defense is the stronger form of combat. Soldiers in combat will sometimes reach a collective conclusion that they can no longer advance in the face of lethal opposition, and will stop and seek cover and concealment to leverage the power of the defense. Exploiting the multiplying effect of the defensive is also a way for a force with weaker combat power to successfully engage a stronger one.

It also relates to the principle of war known as economy of force, as defined in the 1954 edition of the U.S. Army’s Field Manual FM 100-5, Field Service Regulations, Operations:

Minimum essential means must be employed at points other than that of decision. To devote means to unnecessary secondary efforts or to employ excessive means on required secondary efforts is to violate the principle of both mass and the objective. Limited attacks, the defensive, deception, or even retrograde action are used in noncritical areas to achieve mass in the critical area.

These concepts are well ingrained in modern U.S. Army doctrine. FM 3-0 Operations (2017) summarizes the defensive this way:

Defensive tasks are conducted to defeat an enemy attack, gain time, economize forces, and develop conditions favorable for offensive or stability tasks. Normally, the defense alone cannot achieve a decisive victory. However, it can set conditions for a counteroffensive or counterattack that enables Army forces to regain and exploit the initiative. Defensive tasks are a counter to enemy offensive actions. They defeat attacks, destroying as much of an attacking enemy as possible. They also preserve and maintain control over land, resources, and populations. The purpose of defensive tasks is to retain key terrain, guard populations, protect lines of communications, and protect critical capabilities against enemy attacks and counterattacks. Commanders can conduct defensive tasks to gain time and economize forces, so offensive tasks can be executed elsewhere. [Para 1-72]

UPDATE: Just as I posted this, out comes a contrarian view from U.S. Army CAPT Brandon Morgan via the Modern War Institute at West Point blog. He argues that the U.S. Army is not placing enough emphasis on preparing to conduct defensive operations:

In his seminal work On War, Carl von Clausewitz famously declared that, in comparison to the offense, “the defensive form of warfare is intrinsically stronger than the offensive.”

This is largely due to the defender’s ability to occupy key terrain before the attack, and is most true when there is sufficient time to prepare the defense. And yet within the doctrinal hierarchy of the four elements of decisive action (offense, defense, stability, and defense support of civil authorities), the US Army prioritizes offensive operations. Ultimately, this has led to training that focuses almost exclusively on offensive operations at the cost of deliberate planning for the defense. But in the context of a combined arms fight against a near-peer adversary, US Army forces will almost assuredly find themselves initially fighting in a defense. Our current neglect of deliberate planning for the defense puts these soldiers who will fight in that defense at grave risk.

Dupuy’s Verities: The Power Of Defense

Leonidas at Thermopylae, by Jacques-Louis David, 1814. [Wikimedia]

The second of Trevor Dupuy’s Timeless Verities of Combat is:

Defensive strength is greater than offensive strength.

From Understanding War (1987):

[Prussian military theorist, Carl von] Clausewitz expressed this: “Defense is the stronger form of combat.” It is possible to demonstrate by the qualitative comparison of many battles that Clausewitz is right and that posture has a multiplicative effect on the combat power of a military force that takes advantage of terrain and fortifications, whether hasty and rudimentary, or intricate and carefully prepared. There are many well-known examples of the need of an attacker for a preponderance of strength in order to carry the day against a well-placed and fortified defender. One has only to recall Thermopylae, the Alamo, Fredericksburg, Petersburg, and El Alamein to realize the advantage enjoyed by a defender with smaller forces, well placed, and well protected. [p. 2]

The advantages of fighting on the defensive and the benefits of cover and concealment in certain types of terrain have long been basic tenets in military thinking. Dupuy, however, considered defensive combat posture and defensive value of terrain not just to be additive, but combat power multipliers, or circumstantial variables of combat that when skillfully applied and exploited, the effects of which could increase the overall fighting capability of a military force.

The statement [that the defensive is the stronger form of combat] implies a comparison of relative strength. It is essentially scalar and thus ultimately quantitative. Clausewitz did not attempt to define the scale of his comparison. However, by following his conceptual approach it is possible to establish quantities for this comparison. Depending upon the extent to which the defender has had the time and capability to prepare for defensive combat, and depending also upon such considerations as the nature of the terrain which he is able to utilize for defense, my research tells me that the comparative strength of defense to offense can range from a factor with a minimum value of about 1.3 to maximum value of more than 3.0. [p. 26]

The values Dupuy established for posture and terrain based on historical combat experience were as follows:

For example, Dupuy calculated that mounting even a hasty defense in rolling, gentle terrain with some vegetation could increase a force’s combat power by more than 50%. This is a powerful effect, achievable without the addition of any extra combat capability.

It should be noted that these values are both descriptive, in terms of defining Dupuy’s theoretical conception of the circumstantial variables of combat, as well as factors specifically calculated for use in his combat models. Some of these factors have found their way into models and simulations produced by others and some U.S. military doctrinal publications, usually without attribution and shorn of explanatory context. (A good exploration of the relationship between the values Dupuy established for the circumstantial variables of combat and his combat models, and the pitfalls of applying them out of context can be found here.)

While the impact of terrain on combat is certainly an integral part of current U.S. Army thinking at all levels, and is constantly factored into combat planning and assessment, its doctrine does not explicitly acknowledge the classic Clausewitzian notion of a power disparity between the offense and defense. Nor are the effects of posture or terrain thought of as combat multipliers.

However, the Army does implicitly recognize the advantage of the defensive through its stubbornly persistent adherence to the so-called 3-1 rule of combat. Its version of this (which the U.S. Marine Corps also uses) is described in doctrinal publications as “historical minimum planning ratios,” which proscribe that a 3-1 advantage in numerical force ratio is necessary for an attacker to defeat a defender in a prepared or fortified position. Overcoming a defender in a hasty defense posture requires a 2.5-1 force ratio advantage. The force ratio advantages the Army considers necessary for decisive operations are even higher. While the 3-1 rule is a deeply problematic construct, the fact that is the only quantitative planning factor included in current doctrine reveals a healthy respect for the inherent power of the defensive.

Human Factors In Warfare: Friction

The Prussian military philosopher Carl von Clausewitz identified the concept of friction in warfare in his book On War, published in 1832.

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… Countless minor incidents—the kind you can never really foresee—combine to lower the general level of performance, so that one always falls far short of the intended goal… Friction is the only concept that more or less corresponds to the factors that distinguish real war from war on paper… None of [the military machine’s] components is of one piece: each part is composed of individuals, every one of whom retains his potential of friction [and] the least important of whom may chance to delay things or somehow make them go wrong…

[Carl von Clausewitz, On War, Edited and translated by Michael Howard and Peter Paret (Princeton, NJ: Princeton University Press, 1984). Book One, Chapter 7, 119-120.]

While recognizing this hugely significant intangible element, Clausewitz also asserted that “[F]riction…brings about effects that cannot be measured, just they are largely due to chance.” Nevertheless, the clearly self-evident nature of friction in warfare subsequently led to the assimilation of the concept into the thinking of most military theorists and practitioners.

Flash forward 140 years or so. While listening to a lecture on combat simulation, Trevor Dupuy had a flash of insight that led him to conclude that it was indeed possible to measure the effects of friction.[1] Based on his work with historical combat data, Dupuy knew that smaller-sized combat forces suffer higher casualty rates than do larger-sized forces. As the diagram at the top demonstrates, this is partly explained by the fact that small units have a much higher proportion of their front line troops exposed to hostile fire than large units.

However, this relationship can account for only a fraction of friction’s total effect. The average exposure of a company of 200 soldiers is about seven times greater than an army group of 100,000. Yet, casualty rates for a company in intensive combat can be up to 70 times greater than that of an army group. This discrepancy clearly shows the influence of another factor at work.

Dupuy hypothesized that this reflected the apparent influence of the relationship between dispersion, deployment, and friction on combat. As friction in combat accumulates through the aggregation of soldiers into larger-sized units, its effects degrade the lethal effects of weapons from their theoretical maximum. Dupuy calculated that friction affects a force of 100,000 ten times more than it does a unit of 200. Being an ambient, human factor on the battlefield, higher quality forces do a better job of managing friction’s effects than do lower quality ones.

After looking at World War II combat casualty data to calculate the effect of friction on combat, Dupuy looked at casualty rates from earlier eras and found a steady correlation, which he believed further validated his hypothesis.

Despite the consistent fit of the data, Dupuy felt that his work was only the beginning of a proper investigation into the phenomenon.

During the periods of actual combat, the lower the level, the closer the loss rates will approach the theoretical lethalities of the weapons in the hands of the opposing combatants. But there will never be a very close relationship of such rates with the theoretical lethalities. War does not consist merely of a number of duels. Duels, in fact, are only a very small—though integral—part of combat. Combat is a complex process involving interaction over time of many men and numerous weapons combined in a great number of different, and differently organized, units. This process cannot be understood completely by considering the theoretical interactions of individual men and weapons. Complete understanding requires knowing how to structure such interactions and fit them together. Learning how to structure these interactions must be based on scientific analysis of real combat data.

NOTES

[1] This post is based on Trevor N. Dupuy, Understanding War: History and Theory of Combat (New York: Paragon House, 1987), Chapter 14.