Carl von Clausewitz was a Prussian general and influential military theorist. He is most famous for his military treatise Vom Kriege, translated into English as On War.

On War (1832)

Full text online

Book 1

• War therefore is an act of violence to compel our opponent to fulfill our will.
  • Chapter 1, paragraph 2

• Intelligence alone is not courage, we often see that the most intelligent people are irresolute. Since in the rush of events a man is governed by feelings rather than by thought, the intellect needs to arouse the quality of courage, which then supports and sustains it in action.
  • Chapter 3

• We repeat again: strength of character does not consist solely in having powerful feelings, but in maintaining one’s balance in spite of them. Even with the violence of emotion, judgment and principle must still function like a ship’s compass, which records the slightest variations however rough the sea.
  • Chapter 3

• Action in war is like movement in a resistant element. Just as the simplest and most natural of movements, walking, cannot easily be performed in water, so in war it is difficult for normal efforts to achieve even moderate results.
  • Ch. 7, as translated by Michael Howard and Peter Paret (1976)

• Kind-hearted people might of course think there was some ingenious way to disarm or defeat the enemy without too much bloodshed, and might imagine this is the true goal of the art of war. Pleasant as it sounds, it is a fallacy that must be exposed: war is such a dangerous business that the mistakes which come from kindness are the very worst.

• The invention of gunpowder and the constant improvement of firearms are enough in themselves to show that the advance of civilization has done nothing practical to alter or deflect the impulse to destroy the enemy, which is central to the very idea of war.

• The worst of all conditions in which a belligerent can find himself is to be utterly defenseless.

• Men are always more inclined to pitch their estimate of the enemy's strength too high than too low, such is human nature.

• ...only the element of chance is needed to make war a gamble, and that element is never absent.

• ...in the whole range of human activities, war most closely resembles a game of cards.

• Although our intellect always longs for clarity and certainty, our nature often finds uncertainty fascinating.

• With uncertainty in one scale, courage and self-confidence should be thrown into the other to correct the balance. The greater they are, the greater the margin that can be left for accidents.

• ...the side that feels the lesser urge for peace will naturally get the better bargain.

• Blind aggressiveness would destroy the attack itself, not the defense.

• Our discussion has shown that while in war many different roads can lead to the goal, to the attainment of the political object, fighting is the only possible means.

• Any complex activity, if it is to be carried on with any degree of virtuosity, calls for appropriate gifts of intellect and temperament. If they are outstanding and reveal themselves in exceptional achievements, their possessor is called a 'genius'.

• If the mind is to emerge unscathed from this relentless struggle with the unforeseen, two qualities are indispensable: first, an intellect that, even in the darkest hour, retains some glimmerings of the inner light which leads to truth; and second, the courage to follow this faint light wherever it may lead.

• ...the role of determination is to limit the agonies of doubt and the perils of hesitation when the motives for action are inadequate.

• Of all the passions that inspire a man in a battle, none, we have to admit, is so powerful and so constant as the longing for honor and reknown.

• Obstinacy is a fault of temperament. Stubbornness and intolerance of contradiction result from a special kind of egotism, which elevates above everything else the pleasure of its autonomous intellect, to which others must bow.

• ...self-reliance is the best defence against the pressures of the moment.

• Everything in war is simple, but the simplest thing is difficult.

Book 2

• Architects and painters know precisely what they are about as long as they deal with material phenomena. ... But when they come to the aesthetics of their work, when they aim at a particular effect on the mind or on the senses, the rules dissolve into nothing but vague ideas.

• Modern wars are seldom fought without hatred between nations; this serves more or less as a substitute for hatred between individuals.

• ...soldierly simplicity of character that has always represented the military at its best. In the higher ranks it is different. The higher a man is placed, the broader his point of view. Different interests and a wide variety of passions, good and bad, will arise on all sides. Envy and generosity, pride and humility, wrath and compassion - all may appear as effective forces in this great drama.

• ...talent and genius operate outside the rules, and theory conflicts with practice.

• The more physical the activity, the less the difficulties will be. The more the activity becomes intellectual and turns into motives which exercise a determining influence on the commander's will, the more the difficulties will increase.

• Great things alone can make a great mind, and petty things will make a petty mind unless a man rejects them as completely alien.

• Knowledge in war is very simple, being concerned with so few subjects, and only with their final results at that. But this does not make its application easy.

• ...an intellectual instinct which extracts the essence from the phenomena of life, as a bee sucks honey from a flower. In addition to study and reflections, life itself serves as a source.

• Knowledge must be so absorbed into the mind that it ceases to exist in a separate, objective way." "...in 1797 the secret of the effectiveness of resisting to the last had not yet been discovered.

• ...it is better to go on striking in the same direction than to move one's forces this way and that.

• There are times when the utmost daring is the height of wisdom.

• Thus it has come about that our theoretical and critical literature, instead of giving plain, straightforward arguments in which the author at least always knows what he is saying and the reader what he is reading, is crammed with jargon, ending at obscure crossroads where the author loses its readers. Sometimes these books are even worse: they are just hollow shells. The author himself no longer knows just what he is thinking and soothes himself with obscure ideas which would not satisfy him if expressed in plain speech.

• Anyone who feels the urge to undertake such a task must dedicate himself for his labors as he would prepare for a pilgrimage to distant lands. He must spare no time or effort, fear no earthly power or rank, and rise above his own vanity or false modesty in order to tell, in accordance with the expression of the Code Napoléon, the truth, the whole truth, and nothing but the truth.

• Essentally combat is an expression of hostile feelings. But in the large-scale combat that we call war hostile feelings often have become merely hostile intentions. At any rate, there are usually no hostile feelings between individuals. Yet such emotions can never be completely absent from war. Modern wars are seldom fought without hatred between nations; this serves as a more or less substitute for the hatred between individuals. Even when there is no natural hatred and no animosity to start with, the fighting itself will stir up hostile feelings: violence committed on superior orders will stir up the desire for revenge and retaliation against the perpetrator rather than against the powers that ordered the action. It is only human (or animal, if you like), but it is a fact.

Book 3

• A prince or general can best demonstrate his genius by managing a campaign exactly to suit his objectives and his resources, doing neither too much nor too little.

• What we should admire is the acute fulfillment of the unspoken assumptions, the smooth harmony of the whole activity, which only become evident in the final success.

• Where execution is dominant, as it is in the individual events of a war whether great or small, then intellectual factors are reduced to a minimum.

• If we do not learn to regard a war, and the separate campaigns of which it is composed, as a chain of linked engagements each leading to the next, but instead succumb to the idea that the capture of certain geographical points or the seizure of undefended provinces are of value in themselves, we are liable to regard them as windfall profits. In so doing, and in ignoring the fact that they are links in a continuous chain of events, we also ignore the possibility that their possession may later lead to definite disadvantages.

• ...in war, the advantages and disadvantages of a single action could only be determined by the final balance.

• The moral elements are among the most important in war. They constitute the spirit that permeates war as a whole, and at an early stage they establish a close affinity with the will that moves and leads a whole mass of force, practically merging with it, since the will is itself a moral quantity. Unfortunately they will not yield to academic wisdom. They cannot be classified or counted. They have to be seen or felt. ... It is paltry philosophy if in the old-fashioned way one lays down rules and principles in total disregard of moral values. As soon as these appear one regards them as exceptions, which gives them a certain scientific status, and thus makes them into rules. Or again one may appeal to genius, which is above all rules; which amounts to admitting that rules are not only made for idiots, but are idiotic in themselves.
  • Ch 3 : Moral Factors, as translated by Michael Howard and Peter Paret.

• The commander's talents are given greatest scope in rough hilly country. Mountains allow him too little real command over his scattered units and he is unable to control them all; in open country, control is a simple matter and does not test his ability to the fullest.

• Boldness will be at a disadvantage only in an encounter with deliberate caution, which may be considered bold in its own right, and is certainly just as powerful and effective; but such cases are rare.

• Timidity is the root of prudence in the majority of men.

• Boldness governed by superior intellect is the mark of a hero.

• ...as man under pressure tends to give in to physical and intellectual weakness, only great strength of will can lead to the objective.

• Beauty cannot be defined by abscissas and ordinates; neither are circles and ellipses created by their geometrical formulas.

• If a segment of one's force is located where it is not sufficiently busy with the enemy, or if the troops are on the march - that is, idle - while the enemy is fighting, then these forces are being managed uneconomically. In this sense they are being wasted, which is even worse than using them inappropriately.

• ...any move made in a state of tension will be of more important, and will have more results, than it would have made in a state of eqilibrium. In times of maximum tension this importance will rise to an infinite degree.

• The state of crisis is the real war; the equilibrium is nothing but its reflex.

Book 6

• If defense is the stronger form of war, yet has a negative object, it follows that it should be used only so long as weakness compels, and be abandoned as soon as we are strong enough to pursue a positive object.
  • Chapter 1

• Surprise becomes effective when we suddenly face the enemy at one point with far more troops than he expected. This type of numerical superiority is quite distinct from numerical superiority in general: it is the most powerful medium in the art of war.
  • Chapter 2

• Phillipsburg was the name of one those badly drawn fortresses resembling a fool with his nose too close to the wall.
  • Chapter 11

• A general who allows himself to be decisively defeated in an extended mountain position deserves to be court-martialled.
  • Chapter 17

• ...only a fraction of book learning will seep into practical life anyhow; and the more foolish the theory, the less of it.
  • Chapter 23