On War - title image

Carl von Clausewitz

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NOTE: This version of Carl von Clausewitz's On War is the long-obsolete J.J. Graham translation of Clausewitz's Vom Kriege (1832) published in London in 1873. The 1976/84 Howard/Paret version is the  standard translation today; for the most accurate text one should always consult the 1943 Jolles translation. Consider the more modern versions and other relevant books shown below.

Book Cover, ON WATERLOOOn Waterloo: Clausewitz, Wellington, and the Campaign of 1815. Ed./trans. Christopher Bassford, Daniel Moran, and Gregory W. Pedlow (, 2010). ISBN: 1453701508. This book is built around a new and complete translation of Clausewitz's study of the Waterloo campaign [Berlin: 1835], which is a strategic analysis of the entire campaign (not just the Battle of Waterloo), and the Duke of Wellington's detailed 1842 response to it.

Jolles translation, book coverBuy the best translation—recommended for serious readers. The Book of War (The Modern Library, February 2000). ISBN: 0375754776. Clausewitz's On War and Sun Tzu's Art of War in one volume. The translation of Clausewitz's On War is the 1943 version done by German literary scholar O.J. Matthijs Jolles at the University of Chicago during World War II—not today's standard translation, but certainly the most accurate.

On War, Princeton ed.Buy the standard English translation of Clausewitz's On War, by Michael Howard and Peter Paret  (Princeton University Press, 1976/84). ISBN: 0691018545 (paperback). Kindle edition. This quite readable translation appeared at the close of the Vietnam War and—principally for marketing and copyright reasons—has become the modern standard.

Book coverVanya Eftimova Bellinger, Marie von Clausewitz: The Woman Behind the Making of On War (Oxford University Press, 2015), ISBN: 0190225432. A rich biography of Countess Marie von Clausewitz that also sheds enormous light on the life, ideas, influences upon, and character of the great military thinker himself.


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.

The different steps in the defence which we have become acquainted with in the chapter on the methods of defence, are completely homogeneous with these fundamental conditions; there will therefore be no difficulty in connecting them with the same, according to the special requirements of each case. But there is one point which seems at first sight to involve a contradiction in itself, and which, as one of the most important in the defence, requires explanation so much the more. It is the hitting upon the exact centre of gravity of the enemy's force.

If the defender ascertains in time the roads by which the enemy will advance, and upon which in particular the great mass of his force will be found for a certainty, he may march against him on that road. This will be the most usual case, for although the defence precedes the attack in measures of a general nature, in the establishment of strong places, great arsenals, and depôts, and in the peace establishment of his army, and thus gives a line of direction to the assailant in his preparations, still, when the campaign really opens, the defender, in relation to the aggressor, has the peculiar advantage in general of playing the last hand.

To attack a foreign country with a large army, very considerable preparations are required. Provisions, stores, and articles of equipment of all kinds must be collected, which is a work of time. While these preparations are going on, the defender has time to prepare accordingly, in regard to which we must not forget that the defensive requires less time, generally speaking, because in every state things are prepared rather for the defensive than the offensive.

But although this may hold good in the majority of cases, there is always a possibility that, in particular cases, the defensive may remain in uncertainty as to the principal line by which the enemy intends to advance; and this case is more likely to occur when the defence is dependent on measures which of themselves take a good deal of time, as for example, the preparation of a strong position. Further, supposing the defender places himself on the line by which the aggressor is advancing, then, unless the defender is prepared to take the initiative by attacking the aggressor, the latter may avoid the position which the defender has taken up, by only altering a little his line of advance, for in the cultivated parts of Europe we can never be so situated that there are not roads to the right or left by which any position may be avoided. Plainly, in such a case the defender could not wait for his enemy in a position, or at least could not wait there in the expectation of giving battle.

But before entering on the means available to the defensive in this case, we must inquire more particularly into the nature of such a case, and the probability of its occurrence.

Naturally there are in every State, and also in every theatre of war (of which alone we are at present speaking), objects and points upon which an attack is likely to be more efficacious than anywhere else. Upon this we think it will be better to speak when we come to the attack. Here we shall confine ourselves to observing that, if the most advantageous object and point of attack is the motive for the assailant in the direction of his blow, this motive reacts on the defensive, and must be his guide in cases in which he knows nothing of the intentions of his adversary. If the assailant does not take this direction which is favourable to him, he foregoes part of his natural advantages. It is evident that, if the defender has taken up a position in that direction, the evading his position, or passing round, is not to be done for nothing; it costs a sacrifice. From this it follows that there is not on the side of the defender such a risk of missing the direction of his enemy; neither on the other hand, is it so easy for the assailant to pass round his adversary as appears at first sight, because there exists beforehand a very distinct, and in most cases preponderating, motive in favour of one or the other direction, and that consequently the defender, although his preparations are fixed to one spot, will not fail in most cases to come in contact with the mass of the enemy's forces. In other words, if the defender has put himself in the right position, he may be almost sure that the assailant will come to meet him.

But by this we shall not and cannot deny the possibility of the defender sometimes not meeting with the assailant after all these arrangements, and therefore the question arises, what he should then do, and how much of the real advantages of his position still remain available to him.

If we ask ourselves what means still remain generally to the defender when the assailant passes by his position, they are the following:—

1. To divide his forces instantly, so as to be certain to find the assailant with one portion, and then to support that portion with the other.

2. To take up a position with his force united, and in case the assailant passes by him, to push on rapidly in front of him by a lateral movement. In most cases there will not be time to make such a movement directly to a flank, it will therefore be necessary to take up the new position somewhat further back.

3. With his whole force to attack the enemy in flank.

4. To operate against his communications.

5. By a counter attack on his theatre of war, to do exactly what the enemy has done in passing by us.

We introduce this last measure, because it is possible to imagine a case in which it may be efficacious; but as it is in contradiction to the object of the defence, that is, the grounds on which that form has been chosen, therefore it can only be regarded as an abnormity, which can only take place because the enemy has made some great mistake, or because there are other special features in a particular case.

Operating against the enemy's communications implies that our own are superior, which is also one of the fundamental requisites of a good defensive position. But although on that ground this action may promise the defender a certain amount of advantage, still, in the defence of a theatre of war, it is seldom an operation suited to lead to a decision, which we have supposed to be the object of the campaign.

The dimensions of a single theatre of war are seldom so large that the line of communications is exposed to much danger by their length, and even if they were in danger, still the time which the assailant requires for the execution of his blow is usually too short for his progress to be arrested by the slow effects of the action against his communications.

Therefore this means (that is the action against the communications) will prove quite inefficacious in most cases against an enemy determined upon a decision, and also in case the defender seeks such a solution.

The object of the three other means which remain for the defender, is a direct decision—a meeting of centre of force with centre of force; they correspond better, therefore, with the thing required. But we shall at once say that we decidedly prefer the third to the other two, and without quite rejecting the latter, we hold the former to be in the majority of cases the true means of defence.

In a position where our forces are divided, there is always a danger of getting involved in a war of posts, from which, if our adversary is resolute, can follow, under the best of circumstances, only a relative defence on a large scale, never a decision such as we desire; and even if by superior tact we should be able to avoid this mistake, still, by the preliminary resistance being with divided forces, the first shock is sensibly weakened, and we can never be sure that the advanced corps first engaged will not suffer disproportionate losses. To this is to be added that the resistance of this corps which usually ends in its falling back on the main body, appears to the troops in the light of a lost combat, or miscarriage of plans, and the moral force suffers accordingly.

The second means, that of placing our whole force in front of the enemy, in whichever direction he may bend his march, involves a risk of our arriving too late, and thus between two measures, falling short of both. Besides this, a defensive battle requires coolness and consideration, a knowledge, indeed intimate knowledge of the country, which cannot be expected in a hasty oblique movement to a flank. Lastly, positions suitable for a good defensive battle-field are too rarely to be met with to reckon upon them at every point of every road.

On the other hand, the third means, namely to attack the enemy in flank, therefore to give battle with a change of front, is attended with great advantages.

Firstly, there is always in this case, as we know, an exposure of the lines of communication, here the lines of retreat, and in this respect the defender has one advantage in his general relations as defender, and next and chiefly, the advantage which we have claimed for the strategic properties of his position at present.

Secondly,—and this is the principal thing,—every assailant who attempts to pass by his opponent is placed between two opposite tendencies. His first desire is to advance to attain the object of his attack; but the possibility of being attacked in flank at any moment, creates a necessity for being prepared, at any moment, to deliver a blow in that direction, and that too a blow with the mass of his forces. These two tendencies are contradictory, and beget such a complication in the internal relations (of his army), such a difficulty in the choice of measures, if they are to suit every event, that there can hardly be a more disagreeable position strategically. If the assailant knew with certainty the moment when he would be attacked, he might prepare to receive the enemy with skill and ability; but in his uncertainty on this point, and pressed by the necessity of advancing, it is almost certain that when the moment for battle arrives, it finds him in the midst of hurried and half-finished preparations, and therefore by no means in an advantageous relation to his enemy.

If then there are favourable moments for the defender to deliver an offensive battle, it is surely at such a moment as this, above all others, that we may look for success. If we consider, further, that the knowledge of the country and choice of ground are on the side of the defender, that he can prepare his movements, and can time them, no one can doubt that he possesses in such a situation a decided superiority, strategically, over his adversary.

We think, therefore, that a defender occupying a well chosen position, with his forces united, may quietly wait for the enemy passing by his army; should the enemy not attack him in his position, and that an operation against the enemy's communications does not suit the circumstances, there still remains for him an excellent means of bringing about a decision by resorting to a flank attack.

If cases of this kind are hardly to be found in military history, the reason is, partly, that the defender has seldom had the courage to remain firm in such a position, but has either divided his forces, or rashly thrown himself in front of his enemy by a cross or diagonal march, or that no assailant dares to venture past the defender under such circumstances, and in that way his movement usually comes to a stand still.

The defender is in this case compelled to resort to an offensive battle: the further advantages of the state of expectation of a strong position, of good entrenchments, etc., etc., he must give up; in most cases the situation in which he finds the advancing enemy will not quite make up for these advantages, for it is just to evade their influence that the assailant has placed himself in his present situation; still it always offers him a certain compensation, and theory is therefore not just obliged to see a quantity disappear at once from the calculation, to see the pro and contra mutually cancel each other, as so often happens when critical writers of history introduce a little bit of theory.

It must not, in fact, be supposed that we are now dealing with logical subtilties; the subject is rather one which the more it is practically considered, the more it appears as an idea embracing the whole essence of defensive war, everywhere dominating and regulating it.

It is only by the determination on the part of the defender to assail his opponent with all his force, the moment he passes by him, that he avoids two pitfalls, close to which he is led by the defensive form; that is a division of his force, and a hasty flank march to intercept the assailant in front. In both he accepts the law of the assailant; in both he seeks to aid himself through measures of a very critical nature, and with a most dangerous degree of haste; and wherever a resolute adversary, thirsting for victory and a decision, has encountered such a system of defence, he has knocked it on the head. But when the defender has assembled his forces at the right point to fight a general action, if he is determined with this force, come what will, to attack his enemy in flank, he has done right, and is in the right course, and he is supported by all the advantages which the defence can give in his situation; his actions will then bear the stamp of good preparation, coolness, security, unity and simplicity.

We cannot here avoid mentioning a remarkable event in history, which has a close analogy with the ideas now developed; we do so to anticipate its being used in a wrong application.

When the Prussian army was, in October, 1806, waiting in Thuringia for the French under Buonaparte, the former was posted between the two great roads on which the latter might be expected to advance, that is, the road to Berlin by Erfurth, and that by Hof and Leipsic. The first intention of breaking into Franconia straight through the Thuringian Forest, and afterwards, when that plan was abandoned, the uncertainty as to which of the roads the French would choose for their advance, caused this intermediate position. As such, it must therefore have led to the adoption of the measure we have been discussing, a hasty interception of the enemy in front by a lateral movement.

This was in fact the idea in case the enemy marched by Erfurth, for the roads in that direction were good; on the other hand, the idea of a movement of this description on the road by Hof could not be entertained, partly because the army was two or three marches away from that road, partly because the deep valley of the Saale interposed; neither did this plan ever enter into the views of the Duke of Brunswick, so that there was no kind of preparation made for carrying it into effect, but it was always contemplated by Prince Hohenlohe, that is, by Colonel Massenbach, who exerted all his influence to draw the Duke into this plan. Still less could the idea be entertained of leaving the position which had been taken on the left bank of the Saale to try an offensive battle against Buonaparte on his advance, that is, to such an attack in flank as we have been considering; for if the Saale was an obstacle to intercepting the enemy in the last moment (à fortiori) it would be a still greater obstacle to assuming the offensive at a moment when the enemy would be in possession of the opposite side of the river, at least partially. The Duke, therefore, determined to wait behind the Saale to see what would happen, that is to say, if we can call anything a determination which emanated from this many-headed Headquarters' Staff, and in this time of confusion and utter indecision.

Whatever may have been the true condition of affairs during this state of expectation, the consequent situation of the army was this:—

1. That the enemy might be attacked if he crossed the Saale to attack the Prussian army.

2. That if he did not march against that army, operations might be commenced against his communications.

3. If it should be found practicable and advisable, he might be intercepted near Leipsic by a rapid flank march.

In the first case, the Prussian army possessed a great strategic and tactical advantage in the deep valley of the Saale. In the second, the strategic advantage was just as great, for the enemy had only a very narrow base between our position and the neutral territory of Bohemia, whilst ours was extremely broad; even in the third case, our army, covered by the Saale, was still by no means in a disadvantageous situation. All these three measures, in spite of the confusion and want of any clear perception at head-quarters, were really discussed; but certainly we cannot wonder that, although a right idea may have been entertained, it should have entirely failed in the execution by the complete want of resolution and the confusion generally prevailing.

In the two first cases, the position on the left bank of the Saale is to be regarded as a real flank position, and it had undoubtedly as such very great qualities; but in truth, against a very superior enemy, against a Buonaparte, a flank position with an army that is not very sure about what it is doing, is a very bold measure.

After long hesitation, the Duke on the 13th adopted the last of the plans proposed, but it was too late, Buonaparte had already commenced to pass the Saale, and the battles of Jena and Auerstadt were inevitable. The Duke, through his indecision, had set himself between two stools; he quitted his first position too late to push his army in before the enemy, and too soon for a battle suited to the object. Nevertheless, the natural strength of this position proved itself so far that the Duke was able to destroy the right wing of the enemy's army at Auerstadt, whilst Prince Hohenlohe, by a bloody retreat, was still able to back out of the scrape; but at Auerstadt they did not venture to realise the victory, which was quite certain; and at Jena they thought they might reckon upon one which was quite impossible.

In any case, Buonaparte felt the strategic importance of the position on the Saale so much, that he did not venture to pass it by, but determined on a passage of the Saale in sight of the enemy.

By what we have now said we think we have sufficiently specified the relations between the defence and the attack when a decisive course of action is intended, and we believe we have shown also the threads to which, according to their situation and connection, the different subjects of the plan of defence attach themselves. To go through the different arrangements more in detail does not come within our views, for that would lead us into a boundless field of particular cases. When a general has laid down for his direction a distinct point, he will see how far it agrees with geographical, statistical, and political circumstances, the material and personal relations of his own army and that of the enemy, and how the one or the other may require that his plans should be modified in carrying them into effect.

But in order more distinctly to connect and look closer at the gradations in the defence specified in the chapter on the different kinds of defence, we shall here lay before our readers what seems to us most important, in relation to the same generally.

1. Reasons for marching against the enemy with a view to an offensive battle, may be as follows:—

(a) If we know that the enemy is advancing with his forces very much divided, and therefore we have reason to expect a victory, although we are, upon the whole, much weaker.

But such an advance on the part of the assailant is in itself very improbable, and consequently, unless we know of it upon certain information, the plan is not good; for to reckon upon it, and rest all our hopes on it through a mere supposition, and without sufficient motive, leads generally to a very dangerous situation. We do not, then, find things as we expected; we are obliged to give up the offensive battle, we are not prepared to fight on the defensive, we are obliged to commence with a retreat against our will, and leave almost everything to chance.

This is very much what occurred in the defence, conducted by the army under Dohna against the Russians, in the campaign of 1759, and which, under General Wedel, ended in the unfortunate battle of Zullichau.

This measure shortens matters so much that plan-makers are only too ready to propose it, without taking much trouble to inquire how far the hypothesis on which it rests is well founded.

(b) If we are generally in sufficient strength for battle, and—

(c) If a blundering, irresolute adversary specially invites an attack.

In this case the effect of surprise may be worth more than any assistance furnished by the ground through a good position. It is the real essence of good generalship thus to bring into play the power of the moral forces;—but theory can never say loud enough nor often enough there must be an objective foundation for these suppositions; without such foundation to be always talking of surprises and the superiority of novel or unusual modes of attack, and thereon to found plans, considerations, criticisms, is acting without any grounds, and is altogether objectionable.

(d) When the nature of our army makes it specially suited for the offensive.

It was certainly not a visionary or false idea when Frederick the Great conceived that in his mobile, courageous army, full of confidence in him, obedient by habit, trained to precision, animated and elevated by pride, and with its perfection in the oblique attack, he possessed an instrument which, in his firm and daring hand, was much more suited to attack than defence; all these qualities were wanting in his opponents, and in this respect, therefore, he had the most decided superiority; to make use of this was worth more to him, in most cases, than to take to his assistance entrenchments and obstacles of ground.—But such a superiority will always be rare; a well-trained army, thoroughly practised in great movements, has only part of the above advantages. If Frederick the Great maintained that the Prussian army was particularly adapted for attack—and this has been incessantly repeated since his time—still we should not attach too much weight to any such saying; in most cases in war we feel more exhilarated, more courageous when acting offensively than defensively: but this is a feeling which all troops have in common, and there is hardly an army respecting which its generals and leaders have not made the same assertion (as Frederick). We must, therefore, not too readily rely on an appearance of superiority, and through that neglect real advantages.

A very natural and weighty reason for resorting to an offensive battle may be the composition of the army as regards the three arms, for instance, a numerous cavalry and little artillery.

We continue the enumeration of reasons.

(e.) When we can nowhere find a good position.

(f.) When we must hasten with the decision.

(g.) Lastly, the combined influence of several or all of these reasons.

2. The waiting for the enemy in a locality where it is intended to attack him (Minden, 1759) naturally proceeds from—

a, there being no such disproportion of force to our disadvantage as to make it necessary to seek a strong position and strengthen it by entrenchments.

b, a locality having been found particularly adapted to the purpose. The properties which determine this belong to tactics; we shall only observe that these properties chiefly consist in an easy approach for the defender from his side, and in all kinds of obstacles on the side next to the enemy.

3. A position will be taken with the express intention of there waiting the attack of the enemy—

a. If the disproportion of forces compels us to seek cover from natural obstacles or behind field-works.

b. When the country affords an excellent position for our purpose.

The two modes of defence, 2 and 3, will come more into consideration according as we do not seek the decision itself, but content ourselves with a negative result, and have reason to think that our opponent is wavering and irresolute, and that he will in the end fail to carry out his plans.

4. An entrenched unassailable camp only fulfils the object—

a. If it is situated at an extremely important strategic point.

The character of such a position consists in this, that we cannot be driven out of it; the enemy is therefore obliged to try some other means, that is, to pursue his object without touching this camp, or to blockade it and reduce it by starvation: if it is impossible for him to do this, then the strategic qualities of the position must be very great.

b. If we have reason to expect aid from abroad.

Such was the case with the Saxon army in its position at Pirna. Notwithstanding all that has been said against the measure on account of the ill-success which attended it in this instance, it is perfectly certain that 17,000 Saxons could never have been able to neutralise 40,000 Prussians in any other way. If the Austrians were unable to make better use of the superiority obtained at Lowositz, that only shows the badness of their whole method of war, as well as of their whole military organisation; and there cannot be a doubt that if the Saxons instead of taking post in the camp at Pirna had retired into Bohemia, Frederick the Great would have driven both Austrians and Saxons beyond Prague, and taken that place in the same campaign. Whoever does not admit the value of this advantage, and limits his consideration to the capture of the whole Saxon army, shows himself incapable of making a calculation of all the circumstances in a case of this kind, and without calculation no certain deduction can be obtained.

But as the cases a and b very rarely occur, therefore, the entrenched camp is a measure which requires to be well considered, and which is very seldom suitable in practice. The hope of inspiring the enemy with respect by such a camp, and thus reducing him to a state of complete inactivity, is attended with too much danger, namely, with the danger of being obliged to fight without the possibility of retreat. If Frederick the Great gained his object in this way at Bunzelwitz, we must admire the correct judgment he formed of his adversary, but we must certainly also lay more stress than usual on the resources which he would have found at the last moment to clear a road for the remnants of his army, and also on the irresponsibility of a king.

5. If there is one or if there are several fortresses near the frontier, then the great question arises, whether the defender should seek an action before or behind them. The latter recommends itself—

a, by the superiority of the enemy in numbers, which forces us to break his power before coming to a final struggle.

b, by these fortresses being near, so that the sacrifice of territory is not greater than we are compelled to make.

c, by the fitness of the fortresses for defence.

One principal use of fortresses is unquestionably, or should be, to break the enemy's force in his advance and to weaken considerably that portion which we intend to bring to an engagement. If we so seldom see this use made of fortresses, that proceeds from the cases in which a decisive battle is sought for by one of the opposing parties being very rare. But that is the only kind of case which we treat of here. We therefore look upon it as a principle equally simple and important in all cases in which the defender has one or more fortresses near him, that he should keep them before him, and give the decisive battle behind them. We admit that a battle lost within the line of our fortresses will compel us to retreat further into the interior of the country than one lost on the other side, tactical results in both cases being the same, although the causes of the difference have their origin rather in the imagination than in real things; neither do we forget that a battle may be given beyond the fortresses in a well chosen position, whilst inside them the battle in most cases must be an offensive one, particularly if the enemy is laying siege to a fortress which is in danger of being lost; but what signify these nice shades of distinction, as compared to the advantage that, in the decisive battle, we meet the enemy weakened by a fourth or a third of his force, perhaps one half if there are many fortresses?

We think, therefore, that in all cases of an inevitable decision, whether sought for by the offensive or the defensive, and that the latter is not tolerably sure of a victory, or if the nature of the country does not offer some most decisive reason to give battle in a position further forward—in all these cases we say when a fortress is situated near at hand and capable of defence, the defender should by all means withdraw at once behind it, and let the decision take place on this side, consequently with its co-operation. If he takes up his position so close to the fortress that the assailant can neither form the siege of nor blockade the place without first driving him off, he places the assailant under the necessity of attacking him, the defender, in his position. To us, therefore, of all defensive measures in a critical situation, none appears so simple and efficacious as the choice of a good position near to and behind a strong fortress.

At the same time, the question would wear a different aspect if the fortress was situated far back; for then it would be necessary to abandon a considerable part of our theatre of war, a sacrifice which, as we know, should not be made unless in a case of great urgency. In such a case the measure would bear more resemblance to a retreat into the interior of the country.

Another condition is, the fitness of the place for defence. It is well known that there are fortified places, especially large ones, which are not fit to be brought into contact with an enemy's army, because they could not resist the sudden assault of a powerful force. In this case, our position must at all events be so close behind that we could support the garrison.

Lastly, the retreat into the interior of the country is only a natural resource under the following circumstances:—

a, when owing to the physical and moral relation in which we stand as respects the enemy, the idea of a successful resistance on the frontier or near it cannot be entertained.

b, when it is a principal object to gain time.

c, when there are peculiarities in the country which are favourable to the measure, a subject on which we have already treated in the twenty-fifth chapter.

We thus close the chapter on the defence of a theatre of war if a decisive solution is sought for by one or other party, and is therefore inevitable. But it must be particularly borne in mind, that events in war do not exhibit themselves in such a pure abstract form, and that therefore, if our maxims and arguments should be used in reasoning on actual war, our thirtieth chapter should also be kept in view, and we must suppose the general, in the majority of cases, as placed between two tendencies, urged more towards one or the other, according to circumstances.


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