On War

by Carl von Clausewitz

On the other hand, it follows from what precedes, that if we have a decided superiority over the enemy’s principal force, we may designedly pass it by in order at a future time to deliver a more decisive battle.

We have been speaking of a complete victory, therefore of a thorough defeat of the enemy, and not of a mere battle gained. But such a victory requires an enveloping attack, or a battle with an oblique front, for these two forms always give the result a decisive character. It is therefore an essential part of a plan of a war to make arrangements for this movement, both as regards the mass of forces required and the direction to be given them, of which more will be said in the chapter on the plan of campaign.

It is certainly not impossible, that even Battles fought with parallel fronts may lead to complete defeats, and cases in point are not wanting in military history; but such an event is uncommon, and will be still more so the more armies become on a par as regards discipline and handiness in the field. We no longer take twenty-one battalions in a village, as they did at Blenheim.

Once the great victory is gained, the next question is not about rest, not about taking breath, not about considering, not about reorganising, etc., etc., but only of pursuit of fresh blows wherever necessary, of the capture of the enemy’s capital, of the attack of the armies of his allies, or of whatever else appears to be a rallying point for the enemy.

If the tide of victory carries us near the enemy’s fortresses, the laying siege to them or not will depend on our means. If we have a great superiority of force, it would be a loss of time not to take them as soon as possible; but if we are not certain of the further events before us, we must keep the fortresses in check with as few troops as possible, which precludes any regular formal sieges. The moment that the siege of a fortress compels us to suspend our strategic advance, that advance, as a rule, has reached its culminating point. We demand, therefore, that the main body should press forward rapidly in pursuit without any rest; we have already condemned the idea of allowing the advance towards the principal point being made dependent on success at secondary points; the consequence of this is, that in all ordinary cases, our chief army only keeps behind it a narrow strip of territory which it can call its own, and which therefore constitutes its theatre of war. How this weakens the momentum at the head, and the dangers for the offensive arising therefrom, we have shown already. Will not this difficulty, will not this intrinsic counterpoise come to a point which impedes further advance? Certainly that may occur; but just as we have already insisted that it would be a mistake to try to avoid this contracted theatre of war at the commencement, and for the sake of that object to rob the advance of its elasticity, so we also now maintain, that as long as the commander has not yet overthrown his opponent, as long as he considers himself strong enough to effect that object, so long must he also pursue it. He does so perhaps at an increased risk, but also with the prospect of a greater success. If he reaches a point which he cannot venture to go beyond, where, in order to protect his rear, he must extend himself right and left well, then, this is most probably his culminating point. The power of flight is spent, and if the enemy is not subdued, most probably he will not be now.

All that the assailant now does to intensify his attack by conquest of fortresses, defiles, provinces, is no doubt still a slow advance, but it is only of a relative kind, it is no longer absolute. The enemy is no longer in flight, he is perhaps preparing a renewed resistance, and it is therefore already possible that, although the assailant still advances intensively, the position of the defence is every day improving. In short, we come back to this, that, as a rule, there is no second spring after a halt has once been necessary.

Theory, therefore, only requires that, as long as there is an intention of destroying the enemy, there must be no cessation in the advance of the attack; if the commander gives up this object because it is attended with too great a risk, he does right to stop and extend his force. Theory only objects to this when he does it with a view to more readily defeating the enemy.

We are not so foolish as to maintain that no instance can be found of States having been gradually reduced to the utmost extremity. In the first place, the principle we now maintain is no absolute truth, to which an exception is impossible, but one founded only on the ordinary and probable result; next, we must make a distinction between cases in which the downfall of a State has been effected by a slow gradual process, and those in which the event was the result of a first campaign. We are here only treating of the latter case, for it is only in such that there is that tension of forces which either overcomes the centre of gravity of the weight, or is in danger of being overcome by it. If in the first year we gain a moderate advantage, to which in the following we add another, and thus gradually advance towards our object, there is nowhere very imminent danger, but it is distributed over many points. Each pause between one result and another gives the enemy fresh chances: the effects of the first results have very little influence on those which follow, often none, often a negative only, because the enemy recovers himself, or is perhaps excited to increased resistance, or obtains foreign aid; whereas, when all is done in one march, the success of yesterday brings on with itself that of to-day, one brand lights itself from another. If there are cases in which States have been overcome by successive blows in which, consequently, Time, generally the patron of the defensive, has proved adverse how infinitely more numerous are the instances in which the designs of the aggressor have by that means utterly failed. Let us only think of the result of the Seven Years’ War, in which the Austrians sought to attain their object so comfortably, cautiously, and prudently, that they completely missed it.

In this view, therefore, we cannot at all join in the opinion that the care which belongs to the preparation of a theatre of war, and the impulse which urges us onwards, are on a level in importance, and that the former must, to a certain extent, be a counterpoise to the latter; but we look upon any evil which springs out of the forward movement, as an unavoidable evil which only deserves attention when there is no longer hope for us a-head by the forward movement.

Buonaparte’s case in 1812, very far from shaking our opinion, has rather confirmed us in it.