On War

by Carl von Clausewitz

Usually both sides come into action with their physical powers considerably deteriorated, for the movements immediately preceding have generally the character of very urgent circumstances. The efforts which the forging out of a great combat costs, complete the exhaustion; from this it follows that the victorious party is very little less disorganised and out of his original formation than the vanquished, and therefore requires time to reform, to collect stragglers, and issue fresh ammunition to those who are without. All these things place the conqueror himself in the state of crisis of which we have already spoken. If now the defeated force is only a detached portion of the enemy’s Army, or if it has otherwise to expect a considerable reinforcement, then the conqueror may easily run into the obvious danger of having to pay dear for his victory, and this consideration, in such a case, very soon puts an end to pursuit, or at least restricts it materially. Even when a strong accession of force by the enemy is not to be feared, the conqueror finds in the above circumstances a powerful check to the vivacity of his pursuit. There is no reason to fear that the victory will be snatched away, but adverse combats are still possible, and may diminish the advantages which up to the present have been gained. Moreover, at this moment the whole weight of all that is sensuous in an Army, its wants and weaknesses, are dependent on the will of the Commander. All the thousands under his command require rest and refreshment, and long to see a stop put to toil and danger for the present; only a few, forming an exception, can see and feel beyond the present moment, it is only amongst this little number that there is sufficient mental vigour to think, after what is absolutely necessary at the moment has been done, upon those results which at such a moment only appear to the rest as mere embellishments of victory—as a luxury of triumph. But all these thousands have a voice in the council of the General, for through the various steps of the military hierarchy these interests of the sensuous creature have their sure conductor into the heart of the Commander. He himself, through mental and bodily fatigue, is more or less weakened in his natural activity, and thus it happens then that, mostly from these causes, purely incidental to human nature, less is done than might have been done, and that generally what is done is to be ascribed entirely to the thirst for glory, the energy, indeed also the hard-heartedness of the General-in-Chief. It is only thus we can explain the hesitating manner in which many Generals follow up a victory which superior numbers have given them. The first pursuit of the enemy we limit in general to the extent of the first day, including the night following the victory. At the end of that period the necessity of rest ourselves prescribes a halt in any case.

This first pursuit has different natural degrees.

The first is, if cavalry alone are employed; in that case it amounts usually more to alarming and watching than to pressing the enemy in reality, because the smallest obstacle of ground is generally sufficient to check the pursuit. Useful as cavalry may be against single bodies of broken demoralised troops, still when opposed to the bulk of the beaten Army it becomes again only the auxiliary arm, because the troops in retreat can employ fresh reserves to cover the movement, and, therefore, at the next trifling obstacle of ground, by combining all arms they can make a stand with success. The only exception to this is in the case of an army in actual flight in a complete state of dissolution.

The second degree is, if the pursuit is made by a strong advance-guard composed of all arms, the greater part consisting naturally of cavalry. Such a pursuit generally drives the enemy as far as the nearest strong position for his rear-guard, or the next position affording space for his Army. Neither can usually be found at once, and, therefore, the pursuit can be carried further; generally, however, it does not extend beyond the distance of one or at most a couple of leagues, because otherwise the advance-guard would not feel itself sufficiently supported. The third and most vigorous degree is when the victorious Army itself continues to advance as far as its physical powers can endure. In this case the beaten Army will generally quit such ordinary positions as a country usually offers on the mere show of an attack, or of an intention to turn its flank; and the rear-guard will be still less likely to engage in an obstinate resistance.

In all three cases the night, if it sets in before the conclusion of the whole act, usually puts an end to it, and the few instances in which this has not taken place, and the pursuit has been continued throughout the night, must be regarded as pursuits in an exceptionally vigorous form.

If we reflect that in fighting by night everything must be, more or less, abandoned to chance, and that at the conclusion of a battle the regular cohesion and order of things in an army must inevitably be disturbed, we may easily conceive the reluctance of both Generals to carrying on their business under such disadvantageous conditions. If a complete dissolution of the vanquished Army, or a rare superiority of the victorious Army in military virtue does not ensure success, everything would in a manner be given up to fate, which can never be for the interest of any one, even of the most fool-hardy General. As a rule, therefore, night puts an end to pursuit, even when the battle has only been decided shortly before darkness sets in. This allows the conquered either time for rest and to rally immediately, or, if he retreats during the night it gives him a march in advance. After this break the conquered is decidedly in a better condition; much of that which had been thrown into confusion has been brought again into order, ammunition has been renewed, the whole has been put into a fresh formation. Whatever further encounter now takes place with the enemy is a new battle not a continuation of the old, and although it may be far from promising absolute success, still it is a fresh combat, and not merely a gathering up of the débris by the victor.

When, therefore, the conqueror can continue the pursuit itself throughout the night, if only with a strong advance-guard composed of all arms of the service, the effect of the victory is immensely increased, of this the battles of Leuthen and La Belle Alliance(*) are examples.

(*) Waterloo.

The whole action of this pursuit is mainly tactical, and we only dwell upon it here in order to make plain the difference which through it may be produced in the effect of a victory.

This first pursuit, as far as the nearest stopping-point, belongs as a right to every conqueror, and is hardly in any way connected with his further plans and combinations. These may considerably diminish the positive results of a victory gained with the main body of the Army, but they cannot make this first use of it impossible; at least cases of that kind, if conceivable at all, must be so uncommon that they should have no appreciable influence on theory. And here certainly we must say that the example afforded by modern Wars opens up quite a new field for energy. In preceding Wars, resting on a narrower basis, and altogether more circumscribed in their scope, there were many unnecessary conventional restrictions in various ways, but particularly in this point. The conception, Honour of Victory seemed to Generals so much by far the chief thing that they thought the less of the complete destruction of the enemy’s military force, as in point of fact that destruction of force appeared to them only as one of the many means in War, not by any means as the principal, much less as the only means; so that they the more readily put the sword in its sheath the moment the enemy had lowered his. Nothing seemed more natural to them than to stop the combat as soon as the decision was obtained, and to regard all further carnage as unnecessary cruelty. Even if this false philosophy did not determine their resolutions entirely, still it was a point of view by which representations of the exhaustion of all powers, and physical impossibility of continuing the struggle, obtained readier evidence and greater weight. Certainly the sparing one’s own instrument of victory is a vital question if we only possess this one, and foresee that soon the time may arrive when it will not be sufficient for all that remains to be done, for every continuation of the offensive must lead ultimately to complete exhaustion. But this calculation was still so far false, as the further loss of forces by a continuance of the pursuit could bear no proportion to that which the enemy must suffer. That view, therefore, again could only exist because the military forces were not considered the vital factor. And so we find that in former Wars real heroes only—such as Charles XII., Marlborough, Eugene, Frederick the Great—added a vigorous pursuit to their victories when they were decisive enough, and that other Generals usually contented themselves with the possession of the field of battle. In modern times the greater energy infused into the conduct of Wars through the greater importance of the circumstances from which they have proceeded has thrown down these conventional barriers; the pursuit has become an all-important business for the conqueror; trophies have on that account multiplied in extent, and if there are cases also in modern Warfare in which this has not been the case, still they belong to the list of exceptions, and are to be accounted for by peculiar circumstances.