On War

by Carl von Clausewitz

We think, therefore, a theatre of war, whether large or small, with its military force, whatever may be the size of that, represents a unity which maybe reduced to one centre of gravity. At this centre of gravity the decision must take place, and to be conqueror here means to defend the theatre of war in the widest sense.

CHAPTER XXVIII.
Defence of a Theatre of War—(continued)

Defence, however, consists of two different elements, these are the decision and the state of expectation. The combination of these two elements forms the subject of this chapter.

First we must observe that the state of expectation is not, in point of fact, the complete defence; it is only that province of the same in which it proceeds to its aim. As long as a military force has not abandoned the portion of territory placed under its guardianship, the tension of forces on both sides created by the attack continues, and this lasts until there is a decision. The decision itself can only be regarded as having actually taken place when either the assailant or defender has left the theatre of war.

As long as an armed force maintains itself within its theatre, the defence of the same continues, and in this sense the defence of the theatre of war is identical with the defence in the same. Whether the enemy in the meantime has obtained possession of much or little of that section of country is not essential, for it is only lent to him until the decision.

But this kind of idea by which we wish to settle the proper relation of the state of expectation to the whole is only correct when a decision is really to take place, and is regarded by both parties as inevitable. For it is only by that decision that the centres of gravity of the respective forces, and the theatre of war determined through them are effectually hit. Whenever the idea of a decisive solution disappears, then the centres of gravity are neutralised, indeed, in a certain sense, the whole of the armed forces become so also, and now the possession of territory, which forms the second principal branch of the whole theatre of war, comes forward as the direct object. In other words, the less a decisive blow is sought for by both sides in a war, and the more it is merely a mutual observation of one another, so much the more important becomes the possession of territory, so much the more the defensive seeks to cover all directly, and the assailant seeks to extend his forces in his advance.

Now we cannot conceal from ourselves the fact that the majority of wars and campaigns approach much more to a state of observation than to a struggle for life or death, that is, a contest in which one at least of the combatants uses every effort to bring about a complete decision. This last character is only to be found in the wars of the nineteenth century to such a degree that a theory founded on this point of view can be made use of in relation to them. But as all future wars will hardly have this character, and it is rather to be expected that they will again show a tendency to the observation character, therefore any theory to be practically useful must pay attention to that. Hence we shall commence with the case in which the desire of a decision permeates and guides the whole, therefore with real, or if we may use the expression, absolute war; then in another chapter we shall examine those modifications which arise through the approach, in a greater or less degree, to the state of a war of observation.

In the first case (whether the decision is sought by the aggressor or the defender) the defence of the theatre of war must consist in the defender establishing himself there in such a manner, that in a decision he will have an advantage on his side at any moment. This decision may be either a battle, or a series of great combats, but it may also consist in the resultant of mere relations, which arise from the situation of the opposing forces, that is, possible combats.

If the battle were not also the most powerful, the most usual and most effectual means of a decision in war, as we think we have already shown on several occasions, still the mere fact of its being in a general way one of the means of reaching this solution, would be sufficient to enjoin the greatest concentration of our forces which circumstances will in any way permit. A great battle upon the theatre of war is the blow of the centre of force against the centre of force; the more forces can be collected in the one or the other, the surer and greater will be the effect. Therefore every separation of forces which is not called for by an object (which either cannot itself be attained by the successful issue of a battle, or which itself is necessary to the successful issue of the battle) is blameable.

But the greatest concentration of forces is not the only fundamental condition; it is also requisite that they should have such a position and place that the battle may be fought under favourable circumstances.