Le’ Notes #37: A very short introduction to Clausewitz

This post briefly covers Clausewitz’s main ideas on war, with specific reference to Books 1 and 2.

If you have (or are) studying war, the name Clausewitz will always pop up, and for good reason too. His treatise, On War, is one of the foundational texts in the study of war. In it, Clausewitz tries to create a sort of grand theory of war. So, what’s his theory of war? In this post, I’ll go through Clausewitz’s main ideas that make up his (unfinished) theory of war.

Before we go further, I’ll be taking most of the quotations from the Howard and Paret translation, as this is considered the academic standard of all On War translations. There are two versions of the Howard-Paret translation: the first being the original version (1976) and the second being the Everyman’s Library version (1993). Since I have the 1993 version, I’ll be using that as a reference. Note that the major difference is just the page numbering.

On War consists of eight books; however, for those who aren’t studying to become military commanders, you mostly need to be acquainted with Books I and II. These contain the essence of Clausewitz’s thoughts on war. However, if you have the time or are planning to further your understanding on Clausewitz, I suggest you read Bernard Brodie’s guide on how to read On War, present in the Everyman’s edition on page 775. It’s a really nifty study guide.

Book 2: Clausewitz’s theory of war

Clausewitz’s On War is, for the most part, incomplete. Clausewitz himself regarded Chapter 1 of Book 1 to be the part he was completely satisfied with. However, as Michael Handel suggests, you should start with Book 2, because this is where Clausewitz begins to lay out the theoretical and methodological foundations of his theory of war. It’s a bit tedious to read Book 2 because Clausewitz tends to get too philosophical (which becomes a bit of a turn-off for the casual reader), but it’s a rewarding read.

Don’t worry, this is what this post is for.

First, we need to understand the differences between a battle and war. There are engagements, which are the singular acts of fighting between you and the enemy; and then there is war or a collection of engagements that are directed to achieve a political end. As Clausewitz writes,

Tactics teaches the use of armed forces in the engagement; strategy, the use of engagements for the object of the war. (p. 146, emphasis in original)

From here on, Clausewitz goes into detail about what activities are considered preparations for war and war proper, which just serve to further clarify the distinctions between activities related to tactics and strategy. However, we’re much more interested in what Clausewitz has to say on the theory of war, which appears in Chapter 2.

In Book 2, Chapter 2, Clausewitz first starts with criticizing positivistic attempts to formulate the chaotic and seemingly endless practices of war. He notes:

They aim at fixed values; but in war everything is uncertain and calculations have to be made with variable quantities.

They direct the inquiry exclusively toward physical quantities, whereas all military action is intertwined with psychological forces and effects.

They consider only unilateral action, whereas war consists of a continuous interaction of opposites. (p. 156-157)

These three sentences are perhaps the most important statements that highlight Clausewitz’s core thoughts on a theory of war. As you may see, it’s rather impossible to come up with a theory of war because it needs to account for so many uncertain things. How can we positively account for moral factors? What about uncertainty? What of that genius commander who seems to break all rules yet succeeds all the time?

Clausewitz then offers a way out. Theory, he argued, should not be dogmatic; it should only serve as a guide for military strategists. This way, a theory of war would only cover several broad areas that Clausewitz assumes a strategist requires to know and would make their job easier, instead of providing a bunch of prescriptions that promise victory in war. As you may understand by now, since war is ridiculously complex and uncertain, a theory should not act as a straightjacket, but rather, as a set of primary principles for the strategist upon which they may improvise upon. As Clausewitz writes:

[Theory] is meant to educate the mind of the future commander, or, more accurately, to guide him in his self-education, not to accompany him to the battlefield; just as a wise teacher guides and stimulates a young man’s intellectual development, but is careful not to lead him by the hand for the rest of his life. (p. 163)

Now that we have an idea of the what a theory of war may look like, it’s time to move to Book 1, Chapter 1, which is perhaps the most important chapter in all of On War.

Book 1: The essential On War

In the first chapter of Book 1, Clausewitz proposes his definition of war:

War is thus an act of force to compel our enemy to do our will. (p. 83)

Notice how this single sentence manages to capture the essence of war as Clausewitz observed in Book 2, Chapter 2. We can thus understand war as having the following characteristics:

  1. There are two or more opposing sides that are locked in an eternal struggle to impose their will on the other.
  2. The use of physical force is inherent.

Clausewitz’s three extremes

Clausewitz’s three extremes are logical conclusions that we arrive at if we begin to think seriously about the nature of war.

Let’s start with the premise that “war is violent”. When we talk about physical force, we are not just talking about punching or kicking other people. Here, force refers to the manifestation of anything that we can use to inflict damage upon another person, be it guns or nuclear weapons. There is, theoretically, no limit to the accumulation of force. We can, theoretically, have an unlimited stock of weapons which we can use, without limits, to harm the other person. Likewise, the other person will also have such opportunities. Hence, we reach the first of Clausewitz’s extremes: the maximum use of force.

Now that we have so much force, what do we do with it? We want to stop the other person from inflicting harm upon us, or at best, we want them to submit to us. One way to do that is to put them in a position that is always less powerful than us, and we can do this by disarming them or making them defenseless. Likewise, our enemy will think the same and seek to disarm us. We then get locked in a cycle of trying to disarm the enemy, which is the objective of war. Hence, we reach Clausewitz’s second extreme: the aim is to disarm the enemy.

But does this necessarily mean I always have to match or overpower my enemy in physical terms? Note that in Book 2, Clausewitz made the argument that moral factors play a large role in a war. What if you have the guns, but your people are tired of war? That shouldn’t be allowed to happen. So, you try every possible method to increase your will to fight. The opponent will also do this. So, we now become trapped in a cycle of adjusting willpower, thus reaching the third extreme: the maximum exertion of strength.

If war fulfills all of these extremes, it is said to have reached the level of ideal war, the theoretical condition where war engulfs all walks of life without restraint. However, when you think about it, there’s always going to be something that serves to hold back these extreme conditions. What about control mechanisms over the military? What about the resources that are supposed to be for the people’s welfare?

This is where Clausewitz explains the restraints in war. An important restraint is the political objective, which provides a measure of how much force ought to be used. For example, if one wanted to simply send a threatening message to another state, they would not launch their entire arsenal of nuclear missiles. That would defeat the purpose. Another restraint would be the fact that war is waged under uncertain conditions, which would cause the strategist to need time to rethink things, thus causing a delay in the conduct of warfare. The strategist would then need to stop to gather intelligence, reassess and re-calibrate, before moving on.

Due to these restraints, Clausewitz proposes a renewed definition of war:

…war is not merely an act of policy but a true political instrument, a continuation of political intercourse, carried on with other means. (p. 99)

Note the difference with the first definition of war. Here, Clausewitz introduces a political dimension to war that serves to restrain the use of force from reaching the theoretical extremes. He further emphasizes this in his framework for analyzing wars, known as the “paradoxical trinity” (or as some translations have it, “remarkable”).

The Clausewitzian trinity (Zafar Husein)

Hatred and enmity are the psychological factors that make up war. This is reflected in the people, which need to be riled up to get war started. Uncertainty and creativity are represented in chance and probability, or the realm of the military, that have to deal with the fog of war. The political aspect (and specifically, the politician) is represented in reason, which guides the direction of war.

The remainder of Book 1 is dedicated to explaining these elements further, such as coup d’oeil or the “genius” commander (Ch. 3); military friction (Ch. 7), or the things that make armies get bogged down and missions to fail; and the problem of intelligence (Ch. 6). This post will end up being way too long if I discussed all of this. More to come later!


Clausewitz makes for a very difficult, but rewarding read. The first two books attempt to provide some guidelines in trying to understand the complex phenomenon of war, which remains relevant today.

It doesn’t seem right to write any conclusion here since there are so many ways to interpret Clausewitz, but for the sake of completion, here’s my take.

War is political and violent, subject to moral and psychological factors, and is horrendously complex. A theory of war, therefore, should have a degree of flexibility when it comes to dealing with so many unpredictable variables. As such, theory should serve as a guide, rather than dogmatic restraints. These characteristics make Clausewitz’s theory of war timeless and ever so relevant. It’s also why Clausewitz is the most important theorist of war to have ever lived.

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