On War

by Carl von Clausewitz

In the book on the defence, it has been sufficiently explained how far defensive positions can compel the assailant either to attack them, or to give up his advance. Only those which can effect this are subservient to our object, and suited to wear out or neutralise the forces of the aggressor, either wholly or in part, and in so far the attack can do nothing against such positions, that is to say, there are no means at its disposal by which to counter-balance this advantage. But defensive positions are not all really of this kind. If the assailant sees he can pursue his object without attacking such a position, it would be an error to make the attack; if he cannot follow out his object, then it is a question whether he cannot manœuvre the enemy out of his position by threatening his flank. It is only if such means are ineffectual, that a commander determines on the attack of a good position, and then an attack directed against one side, always in general presents the less difficulty; but the choice of the side must depend on the position and direction of the mutual lines of retreat, consequently, on the threatening the enemy’s retreat, and covering our own. Between these two objects a competition may arise, in which case the first is entitled to the preference, as it is of an offensive nature; therefore homogeneous with the attack, whilst the other is of a defensive character. But it is certain, and may be regarded as a truth of the first importance, that to attack an enemy thoroughly inured to war, in a good position, is a critical thing. No doubt instances are not wanting of such battles, and of successful ones too, as Torgau, Wagram (we do not say Dresden, because we cannot call the enemy there quite aguerried); but upon the whole, the danger is small, and it vanishes altogether, opposed to the infinite number of cases in which we have seen the most resolute commanders make their bow before such positions. (Torres Vedras.)

We must not, however, confuse the subject now before us with ordinary battles. Most battles are real “rencontres,” in which one party certainly occupies a position, but one which has not been prepared.

CHAPTER X.
Attack on an Entrenched Camp

It was for a time the fashion to speak with contempt of entrenchments and their utility. The cordon lines of the French frontier, which had been often burst through; the entrenched camp at Breslau in which the Duke of Bevern was defeated, the battle of Torgau, and several other cases, led to this opinion of their value; and the victories of Frederick the Great, gained by the principle of movement and the use of the offensive, threw a fresh light on all kind of defensive action, all fighting in a fixed position, particularly in intrenchments, and brought them still more into contempt. Certainly, when a few thousand men are to defend several miles of country, and when entrenchments are nothing more than ditches reversed, they are worth nothing, and they constitute a dangerous snare through the confidence which is placed in them. But is it not inconsistent, or rather nonsensical, to extend this view even to the idea of field fortification, in a mere swaggering spirit (as Templehof does)? What would be the object of entrenchments generally, if not to strengthen the defence? No, not only reason but experience, in hundreds and thousands of instances, show that a well-traced, sufficiently manned, and well defended entrenchment is, as a rule, to be looked upon as an impregnable point, and is also so regarded by the attack. Starting from this point of the efficiency of a single entrenchment, we argue that there can be no doubt as to the attack of an entrenched camp being a most difficult undertaking, and one in which generally it will be impossible for the assailant to succeed.

It is consistent with the nature of an entrenched camp that it should be weakly garrisoned; but with good, natural obstacles of ground and strong field works, it is possible to bid defiance to superior numbers. Frederick the Great considered the attack of the camp of Pirna as impracticable, although he had at his command double the force of the garrison; and although it has been since asserted, here and there, that it was quite possible to have taken it; the only proof in favour of this assertion is founded on the bad condition of the Saxon troops; an argument which does not at all detract in any way from the value of entrenchments. But it is a question, whether those who have since contended not only for the feasibility but also for the facility of the attack, would have made up their minds to execute it at the time.

We, therefore, think that the attack of an entrenched camp belongs to the category of quite exceptional means on the part of the offensive. It is only if the entrenchments have been thrown up in haste are not completed, still less strengthed by obstacles to prevent their being approached, or when, as is often the case taken altogether, the whole camp is only an outline of what it was intended to be, a half-finished ruin, that then an attack on it may be advisable, and at the same time become the road to gain an easy conquest over the enemy.

CHAPTER XI.
Attack on a Mountain

From the fifth and following chapters of the sixth book, may be deduced sufficiently the strategic relations of a mountain generally, both as regards the defence and the attack. We have also there endeavoured to explain the part which a mountain plays as a line of defence, properly so called, and from that naturally follows how it is to be looked upon in this signification from the side of the assailant. There remains, therefore, little for us to say here on this important subject. Our chief result was there that the defence must choose as his point of view a secondary combat, or the entirely different one of a great general action; that in the first case the attack of a mountain can only be regarded as a necessary evil, because all the circumstances are unfavourable to it; but in the second case the advantages are on the side of the attack.

An attack, therefore, armed with the means and the resolution for a battle, will give the enemy a meeting in the mountains, and certainly find his account in so doing.

But we must here once more repeat that it will be difficult to obtain respect for this conclusion, because it runs counter to appearances, and is also, at first sight, contrary to the experience of war. It has been observed, in most cases hitherto, that an army pressing forward to the attack (whether seeking a great general action or not), has considered it an unusual piece of good fortune if the enemy has not occupied the intervening mountains, and has itself then hastened to be beforehand in the occupation of them. No one will find this forestalling of the enemy in any way inconsistent with the interests of the assailant; in our view this is also quite admissible, only we must point out clearly a fine distinction here between circumstances.