Book SummaryOn War, by Carl von Clausewitz

1-Page Summary1-Page Book Summary of On War

On War by Carl von Clausewitz is arguably the most influential Western treatise on the subject of war. Clausewitz was a Prussian general who fought in the Napoleonic wars in the early 1800s, and he wrote extensively about military philosophy, strategy, and tactics.

The book consists of a large collection of essays. The author expressed an intent to develop them into a comprehensive textbook for military officers, politicians, and others who needed to understand...

On War Summary Philosophical Principles

We’ve grouped Clausewitz’s philosophical principles into three categories. First, we’ll discuss his perspectives on why war exists and the purpose it serves. Then, we’ll examine his views on what war really is—its essential nature. Finally, we’ll consider his ideas on the academic study of war and the criteria that any theory of war must meet.

The Purpose of War

According to Clausewitz, war is nothing but a tool of politics. When different nations or groups have conflicting political interests, one way to make the other side accommodate your interests is to compel them by means of military force. This, then, is the purpose of war: to force the enemy to comply with some kind of political demand. For example, maybe one country demands control of a region currently controlled by another country and invades that region if the other country refuses to cede it. Or perhaps an interest group within a country demands governmental reform and starts a revolutionary war if the government doesn’t reform.

(Shortform note: Robert Greene turns this definition of war around and uses it as the basis of his book _[The 33 Strategies of...

On War Summary Tactics and Strategy in a Model War

Now that we understand Clausewitz’s views on what war is, what it’s for, and the difficulty of developing theories that are faithful to the reality of war, we can consider his practical advice on tactics and strategy from his viewpoint.

To understand his advice, it’s also helpful to picture the context in which he meant it to be applied. Documenting the normal operations of the military in his day was not Clausewitz’s primary purpose in writing, but he mentions many aspects of these operations in passing. And since the normal operations of armies in the Napoleonic era are no longer common knowledge (as they would have been to Clausewitz’s original audience), we’ve used the information that he provided in passing to describe a hypothetical war, which should furnish the necessary context.

However, before we dive into our hypothetical war story and use it to present Clausewitz’s ideas about tactics and strategy, we need to clarify what he meant by “tactics” and “strategy.”

The Relationship Between Tactics and Strategy

Throughout the book, Clausewitz is careful to differentiate between strategy and tactics. Strategy is about picking your battles to achieve the ultimate...

Shortform Exercise: Apply Clausewitz’s Philosophical Observations on War

In the following questions, we’ll revisit Clausewitz’s philosophical discussion of war and give you a chance to reflect on how some of the issues he addresses apply to you.

As we discussed, Clausewitz identifies physical violence—people trying to kill each other—as the essence of war. He also makes the point that, in general, war only happens when people fight back against an aggressor instead of yielding to the aggressor's demands. Do you believe it’s ever appropriate to resort to violence in resisting someone’s demands? If so, when is it appropriate? If not, why not? Note your thoughts below.

Shortform Exercise: Apply Tactical and Strategic Advice to Your Life

In the following questions, we’ll revisit some of Clausewitz’s tactical and strategic advice, giving you a chance to consider how it might be applicable to your own situation.

Clausewitz stresses the importance of traveling light so that the army can move faster and focus on its main objectives, rather than devoting a lot of manpower to coordinating supply lines. A similar principle applies to travel in general: The more baggage you carry, the more energy you’ll expend lugging it around, and the less you’ll have left to focus on the purpose of your trip. Think about your most recent vacation or business trip. Did you pack any items that you never used on the trip? If so, what were they? What items did you bring along that you could have purchased or borrowed locally when you needed them?