On War
Clausewitz (1827)

Book II: On the Theory of War

Chapter I. Branches of the Art of War


War in its literal meaning is fighting, for fighting alone is the efficient principle in the manifold activity which in a wide sense is called War. But fighting is a trial of strength of the moral and physical forces by means of the latter. That the moral cannot be omitted is evident of itself, for the condition of the mind has always the most decisive influence on the forces employed in War.

The necessity of fighting very soon led men to special inventions to turn the advantage in it in their own favour: in consequence of these the mode of fighting has undergone great alterations; but in whatever way it is conducted its conception remains unaltered, and fighting is that which constitutes War.

The inventions have been from the first weapons and equipments for the individual combatants. These have to be provided and the use of them learnt before the War begins. They are made suitable to the nature of the fighting, consequently are ruled by it; but plainly the activity engaged in these appliances is a different thing from the fight itself; it is only the preparation for the combat, not the conduct of the same. That arming and equipping are not essential to the conception of fighting is plain, because mere wrestling is also fighting.

Fighting has determined everything appertaining to arms and equipment, and these in turn modify the mode of fighting; there is, therefore, a reciprocity of action between the two.

Nevertheless, the fight itself remains still an entirely special activity, more particularly because it moves in an entirely special element, namely, in the element of danger.

If, then, there is anywhere a necessity for drawing a line between two different activities, it is here; and in order to see clearly the importance of this idea, we need only just to call to mind how often eminent personal fitness in one field has turned out nothing but the most useless pedantry in the other.

It is also in no way difficult to separate in idea the one activity from the other, if we look at the combatant forces fully armed and equipped as a given means, the profitable use of which requires nothing more than a knowledge of their general results.

The Art of War is therefore, in its proper sense, the art of making use of the given means in fighting, and we cannot give it a better name than the “Conduct of War.” On the other hand, in a wider sense all activities which have their existence on account of War, therefore the whole creation of troops, that is levying them, arming, equipping, and exercising them, belong to the Art of War.

To make a sound theory it is most essential to separate these two activities, for it is easy to see that if every act of War is to begin with the preparation of military forces, and to presuppose forces so organised as a primary condition for conducting War, that theory will only be applicable in the few cases to which the force available happens to be exactly suited. If, on the other hand, we wish to have a theory which shall suit most cases, and will not be wholly useless in any case, it must be founded on those means which are in most general use, and in respect to these only on the actual results springing from them.

The conduct of War is, therefore, the formation and conduct of the fighting. If this fighting was a single act, there would be no necessity for any further subdivision, but the fight is composed of a greater or less number of single acts, complete in themselves, which we call combats, as we have shown in the first chapter of the first book, and which form new units. From this arises the totally different activities, that of the formation and conduct of these single combats in themselves, and the combination of them with one another, with a view to the ultimate object of the War. The first is called tactics, the other strategy.

This division into tactics and strategy is now in almost general use, and every one knows tolerably well under which head to place any single fact, without knowing very distinctly the grounds on which the classification is founded. But when such divisions are blindly adhered to in practice, they must have some deep root. We have searched for this root, and we might say that it is just the usage of the majority which has brought us to it. On the other hand, we look upon the arbitrary, unnatural definitions of these conceptions sought to be established by some writers as not in accordance with the general usage of the terms.

According to our classification, therefore, tactics is the theory of the use of military forces in combat. Strategy is the theory of the use of combats for the object of the war.

The way in which the conception of a single, or independent combat, is more closely determined, the conditions to which this unit is attached, we shall only be able to explain clearly when we consider the combat; we must content ourselves for the present with saying that in relation to space, therefore in combats taking place at the same time, the unit reaches just as far as personal command reaches; but in regard to time, and therefore in relation to combats which follow each other in close succession, it reaches to the moment when the crisis which takes place in every combat is entirely passed.

That doubtful cases may occur, cases, for instance, in which several combats may perhaps be regarded also as a single one, will not overthrow the ground of distinction we have adopted, for the same is the case with all grounds of distinction of real things which are differentiated by a gradually diminishing scale. There may, therefore, certainly be acts of activity in War which, without any alteration in the point of view, may just as well be counted strategic as tactical; for example, very extended positions resembling a chain of posts, the preparations for the passage of a river at several points, &.

Our classification reaches and covers only the use of the military force. But now there are in War a number of activities which are subservient to it, and still are quite different from it; sometimes closely allied, sometimes less near in their affinity. All these activities relate to the maintenance of the military force. In the same way as its creation and training precede its use, so its maintenance is always a necessary condition. But, strictly viewed, all activities thus connected with it are always to be regarded only as preparations for fighting; they are certainly nothing more than activities which are very close to the action, so that they run through the hostile act alternate in importance with the use of the forces. We have therefore a right to exclude them as well as the other preparatory activities from the Art of War in its restricted sense, from the conduct of War properly so called; and we are obliged to do so if we would comply with the first principle of all theory, the elimination of all heterogeneous elements. Who would include in the real “conduct of War” the whole litany of subsistence and administration, because it is admitted to stand in constant reciprocal action with the use of the troops, but is something essentially different from it?

We have said, in the third chapter of our first book, that as the fight or combat is the only directly effective activity, therefore the threads of all others, as they end in it, are included in it. By this we meant to say that to all others an object was thereby appointed which, in accordance with the laws peculiar to themselves, they must seek to attain. Here we must go a little closer into this subject.

The subjects which constitute the activities outside of the combat are of various kinds.

The one part belongs, in one respect, to the combat itself, is identical with it, whilst it serves in another respect for the maintenance of the military force. The other part belongs purely to the subsistence, and has only, in consequence of the reciprocal action, a limited influence on the combats by its results. The subjects which in one respect belong to the fighting itself are marches, camps, and cantonments, for they suppose so many different situations of troops, and where troops are supposed there the idea of the combat must always be present.

The other subjects, which only belong to the maintenance, are subsistence, care of the sick, the supply and repair of arms and equipment.

Marches are quite identical with the use of the troops. The act of marching in the combat, generally called manoeuvring, certainly does not necessarily include the use of weapons, but it is so completely and necessarily combined with it that it forms an integral part of that which we call a combat. But the march outside the combat is nothing but the execution of a strategic measure. By the strategic plan is settled when, where, and with what forces a battle is to be delivered — and to carry that into execution the march is the only means.

The march outside of the combat is therefore an instrument of strategy, but not on that account exclusively a subject of strategy, for as the armed force which executes it may be involved in a possible combat at any moment, therefore its execution stands also under tactical as well as strategic rules. If we prescribe to a column its route on a particular side of a river or of a branch of a mountain, then that is a strategic measure, for it contains the intention of fighting on that particular side of the hill or river in preference to the other, in case a combat should be necessary during the march.

But if a column, instead of following the road through a valley, marches along the parallel ridge of heights, or for the convenience of marching divides itself into several columns, then these are tactical arrangements, for they relate to the manner in which we shall use the troops in the anticipated combat.

The particular order of march is in constant relation with readiness for combat, is therefore tactical in its nature, for it is nothing more than the first or preliminary disposition for the battle which may possibly take place.

As the march is the instrument by which strategy apportions its active elements, the combats, but these last often only appear by their results and not in the details of their real course, it could not fail to happen that in theory the instrument has often been substituted for the efficient principle. Thus we hear of a decisive skilful march, allusion being thereby made to those combat- combinations to which these marches led. This substitution of ideas is too natural and conciseness of expression too desirable to call for alteration, but still it is only a condensed chain of ideas in regard to which we must never omit to bear in mind the full meaning, if we would avoid falling into error.

We fall into an error of this description if we attribute to strategical combinations a power independent of tactical results. We read of marches and manoeuvres combined, the object attained, and at the same time not a word about combat, from which the conclusion is drawn that there are means in War of conquering an enemy without fighting. The prolific nature of this error we cannot show until hereafter.

But although a march can be regarded absolutely as an integral part of the combat, still there are in it certain relations which do not belong to the combat, and therefore are neither tactical nor strategic. To these belong all arrangements which concern only the accommodation of the troops, the construction of bridges, roads, &. These are only conditions; under many circumstances they are in very close connection, and may almost identify themselves with the troops, as in building a bridge in presence of the enemy; but in themselves they are always activities, the theory of which does not form part of the theory of the conduct of War.

Camps, by which we mean every disposition of troops in concentrated, therefore in battle order, in contradistinction to cantonments or quarters, are a state of rest, therefore of restoration; but they are at the same time also the strategic appointment of a battle on the spot, chosen; and by the manner in which they are taken up they contain the fundamental lines of the battle, a condition from which every defensive battle starts; they are therefore essential parts of both strategy and tactics.

Cantonments take the place of camps for the better refreshment of the troops. They are therefore, like camps, strategic subjects as regards position and extent; tactical subjects as regards internal organisation, with a view to readiness to fight.

The occupation of camps and cantonments no doubt usually combines with the recuperation of the troops another object also, for example, the covering a district of country, the holding a position; but it can very well be only the first. We remind our readers that strategy may follow a great diversity of objects, for everything which appears an advantage may be the object of a combat, and the preservation of the instrument with which War is made must necessarily very often become the object of its partial combinations.

If, therefore, in such a case strategy ministers only to the maintenance of the troops, we are not on that account out of the field of strategy, for we are still engaged with the use of the military force, because every disposition of that force upon any point Whatever of the theatre of War is such a use.

But if the maintenance of the troops in camp or quarters calls forth activities which are no employment of the armed force, such as the construction of huts, pitching of tents, subsistence and sanitary services in camps or quarters, then such belong neither to strategy nor tactics.

Even entrenchments, the site and preparation of which are plainly part of the order of battle, therefore tactical subjects, do not belong to the theory of the conduct of War so far as respects the execution of their construction the knowledge and skill required for such work being, in point of fact, qualities inherent in the nature of an organised Army; the theory of the combat takes them for granted.

Amongst the subjects which belong to the mere keeping up of an armed force, because none of the parts are identified with the combat, the victualling of the troops themselves comes first, as it must be done almost daily and for each individual. Thus it is that it completely permeates military action in the parts constituting strategy — we say parts constituting strategy, because during a battle the subsistence of troops will rarely have any influence in modifying the plan, although the thing is conceivable enough. The care for the subsistence of the troops comes therefore into reciprocal action chiefly with strategy, and there is nothing more common than for the leading strategic features of a campaign and War to be traced out in connection with a view to this supply. But however frequent and however important these views of supply may be, the subsistence of the troops always remains a completely different activity from the use of the troops, and the former has only an influence on the latter by its results.

The other branches of administrative activity which we have mentioned stand much farther apart from the use of the troops. The care of sick and wounded, highly important as it is for the good of an Army, directly affects it only in a small portion of the individuals composing it, and therefore has only a weak and indirect influence upon the use of the rest. The completing and replacing articles of arms and equipment, except so far as by the organism of the forces it constitutes a continuous activity inherent in them — takes place only periodically, and therefore seldom affects strategic plans.

We must, however, here guard ourselves against a mistake. In certain cases these subjects may be really of decisive importance. The distance of hospitals and depo^ts of munitions may very easily be imagined as the sole cause of very important strategic decisions. We do not wish either to contest that point or to throw it into the shade. But we are at present occupied not with the particular facts of a concrete case, but with abstract theory; and our assertion therefore is that such an influence is too rare to give the theory of sanitary measures and the supply of munitions and arms an importance intheory of the conduct of War such as to make it worth while to include in the theory of the conduct of War the consideration of the different ways and systems which the above theories may furnish, in the same way as is certainly necessary in regard to victualling troops.

If we have clearly understood the results of our reflections, then the activities belonging to War divide themselves into two principal classes, into such as are only “preparations for War” and into the “War itself.” This division must therefore also be made in theory.

The knowledge and applications of skill in the preparations for War are engaged in the creation, discipline, and maintenance of all the military forces; what general names should be given to them we do not enter into, but we see that artillery, fortification, elementary tactics, as they are called, the whole organisation and administration of the various armed forces, and all such things are included. But the theory of War itself occupies itself with the use of these prepared means for the object of the war. It needs of the first only the results, that is, the knowledge of the principal properties of the means taken in hand for use. This we call “The Art of War” in a limited sense, or “Theory of the Conduct of War,” or “Theory of the Employment of Armed Forces,” all of them denoting for us the same thing.

The present theory will therefore treat the combat as the real contest, marches, camps, and cantonments as circumstances which are more or less identical with it. The subsistence of the troops will only come into consideration like other given circumstances in respect of its results, not as an activity belonging to the combat.

The Art of War thus viewed in its limited sense divides itself again into tactics and strategy. The former occupies itself with the form of the separate combat, the latter with its use. Both connect themselves with the circumstances of marches, camps, cantonments only through the combat, and these circumstances are tactical or strategic according as they relate to the form or to the signification of the battle.

No doubt there will be many readers who will consider superfluous this careful separation of two things lying so close together as tactics and strategy, because it has no direct effect on the conduct itself of War. We admit, certainly that it would be pedantry to look for direct effects on the field of battle from a theoretical distinction.

But the first business of every theory is to clear up conceptions and ideas which have been jumbled together, and, we may say, entangled and confused; and only when a right understanding is established, as to names and conceptions, can we hope to progress with clearness and facility, and be certain that author and reader will always see things from the same point of view. Tactics and strategy are two activities mutually permeating each other in time and space, at the same time essentially different activities, the inner laws and mutual relations of which cannot be intelligible at all to the mind until a clear conception of the nature of each activity is established.

He to whom all this is nothing, must either repudiate all theoretical consideration, or his understanding has not as yet been pained by the confused and perplexing ideas resting on no fixed point of view, leading to no satisfactory result, sometimes dull, sometimes fantastic, sometimes floating in vague generalities, which we are often obliged to hear and read on the conduct of War, owing to the spirit of scientific investigation having hitherto been little directed to these subjects.