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III.—: STRATEGY. - Carl von Clausewitz, On War, vol. 3 
On War, trans. Col. J.J. Graham. New and Revised edition with Introduction and Notes by Col. F.N. Maude, in Three Volumes (London: Kegan Paul, Trench, Trubner & C., 1918). Vol. 3.
Part of: On War
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This is the combination of the singles battles of a War, in order to attain to the object of the campaign.
If we know how to fight, if we know how to conquer, there is not much more wanted; to combine successful results is easy, because it is merely an affair of a well-practised judgment, and does not depend, like the direction of a battle, on special knowledge.
All that is essential in the few principles which there are, and which depend chiefly on the constitution of States and Armies may, therefore, be brought within a small compass.
(1) There are three principal objects in carrying on War:
(a) To conquer and destroy the enemy’s armed force.
(b) To get possession of the material elements of aggression, and of the other sources of existence of the hostile Army.
(c) To gain public opinion.
(2) To attain the first of these objects, the chief operation must be directed against the enemy’s principal Army, or at least against a very important portion of the hostile force; for it must be beaten before we can follow up the other two objects with success.
(3) In order to seize the material forces, operations are directed against those points at which those resources are chiefly concentrated: principal towns, magazines, great fortresses. On the road to these, the enemy’s principal force, or a considerable part of his Army, will be encountered.
(4) Public opinion is ultimately gained by great victories, and by the possession of the enemy’s capital.
(5) The first and most important maxim which we can set before us for the attainment of these objects is: to employ all the forces which we can make available with the utmost energy. In every modification which manifests itself in these respects, there is a shortcoming as respects the object. Even if the result is tolerably certain in itself, it is extremely unwise not to use the utmost efforts to make it perfectly certain; for these efforts can never produce injurious effects. Let the country suffer ever so much by it, no disadvantage can arise from that, because the pressure of the War is the sooner removed.
The moral impression produced by vigorous preparations is of infinite value; every one feels certain of success: this is the best means of raising the spirits of the Nation.
(6) The second principle is to concentrate our force as much as is possible at the point where the decisive blows are to be struck, to run the risk even of being at a disadvantage at other points, in order to make sure of the result at the decisive point. The success at that point will compensate for all defeats at secondary points.
(7) The third principle is: not to lose time. If no special and considerable advantage will arise by delay, it is important to commence work as quickly as possible. By rapidity, many measures of the enemy are nipped in the bud, and public opinion is gained in our favour.
Surprise plays a much greater part in Strategy than in tactics; it is the most powerful element of victory; Alexander, Hannibal, Cæsar, Gustavus Adolphus, Frederick II., Napoleon, owe the brightest rays of their fame to their promptitude.
(8) Lastly, the fourth principle is: to follow up the success we gain with the utmost energy.
The pursuit of the enemy when defeated is the only means of gathering up the fruits of victory.
(9) The first of these principles is the foundation of the three others. If we have followed the first principle, we can venture any length with respect to the others, without risking our all. It gives the means of continually creating new forces behind us, and with fresh forces every disaster may be repaired.
In this, and not in going forward with timid steps, lies that prudence which may be called wise.
(10) Small States, in the present day, cannot make any Wars of conquest; but, at the same time, for a defensive War, even their means are very great. Therefore I am perfectly convinced that hoever calls forth all his powers in order to appear incessantly with new masses, whoever adopts every imaginable means of preparation, whoever concentrates his force at the decisive point, whoever thus armed pursues a great object with resolution and energy, has done all that can be done in a general way for the strategical conduct of the War, and that unless he is altogether unfortunate in battle, he will undoubtedly be victorious in the same measure as his adversary has fallen short of this exertion and energy.
(11) Due attention being paid to these principles, the form in which the operations are carried on is in the end of little consequence. I shall, however, try to explain, in a few words, what is most important.
In tactics, we always seek to get round the enemy, that is to say, that portion of his force against which our principal attack is directed, partly because the convergent action of the combatant force is more advantageous than the parallel, partly because it is the only method of cutting the enemy off from his line of retreat.
If this, which relates to the enemy and his position tactically, issued strategically, and applied to the enemy’s theatre of War (therefore also to his subsistence lines), then the separate columns, or Armies, which should envelop the enemy, will be in most cases so far apart from each other that they cannot take part in one and the same battle. The enemy will be in the middle, and may be able to turn with the mass of his forces against these Corps singly, and beat them in detail. Frederick II.’s campaigns furnish examples of this, more especially those of 1757 and 1758.
Now as the battle is the principal affair, the decisive one, the party acting on converging lines, unless he has a most decisive superiority in numbers, will lose by battles all the advantages which the enveloping movement would have gained for him; for an operation against the lines of communication only takes effect very slowly, but victory in the battle very quickly.
Therefore, in Strategy, he who finds himself in the midst of his enemies is better off than his opponent who tries to envelop him, particularly if the forces on each side are equal, and of course still more so if there is an inferiority on the enveloping side.
A strategic enveloping or turning movement is no doubt a very effective means of cutting the enemy off from his line of retreat; but as this object may also just as well be attained by a tactical turning movement, the strategic enveloping movement is therefore never advisable unless we are (physically and morally) so superior, that we shall be strong enough at the decisive point, and yet can at the same time dispense with the detached corps.
Napoleon never engaged in attempts to turn his enemy strategically, although he was so often, indeed almost always, both physically and morally superior.
Frederick II. only did it once, in the attack on Bohemia, 1757. Certainly by that means the Austrians were prevented from bringing on a battle until they got to Prague; but what was the benefit to him of the conquest of Bohemia as far as Prague, without a decisive battle? The battle of Kollin forced him to give it up again—a proof that battles decide all. At Prague he was obviously in danger of being attacked by the whole of the Austrian forces before the arrival of Schwerin. He would not have exposed himself to this danger if he had marched through Saxony with all his forces united. The first battle would in that case probably have been fought at Budin on the Eger, and that would have been as decisive as the Battle of Prague. This concentric march into Bohemia was unquestionably a consequence of the Prussian Army having been broken up during the winter in cantonments in Silesia and Saxony, and it is of importance to observe, that reasons of this kind, in most cases, are more influential than the advantages in the form of the disposition itself, for the facility of operations is favourable to their rapid execution, and the friction inherent in the immense machinery of a great armed force is in any case so great that we should never add to it except from necessity.
(12) Besides this, the principle just stated, of concentrating as much as possible at the decisive point, is opposed to the idea of enveloping strategically, and the order of battle for our troops naturally springs from that principle of itself. On that account I said, with reason, that the form of the order of battle is of little consequence. There is, however, one case in which the operating strategically against the enemy’s flank leads to great results, similar to those of a battle; that is, when in a poor or impoverished country the enemy, by great exertions, has formed large magazines, on the preservation of which his operations entirely depend. In such a case it may perhaps be advisable not to march with the mass of our forces against the enemy’s principal force, but to push forward against his base. For this there are, however, two conditions requisite:
(a) That the enemy is so far from his base that he will be forced by this means to make a long retreat; and
(b) That with a few troops and the help of natural and artificial obstacles we shall be able to harass him in such a manner on the road which his principal force must take, that no conquests he can make in that direction will compensate for the loss of his base.
(13) The subsistence of troops being a condition which is indispensable in the conduct of War, it has a great influence on the operations of the War, particularly in this way, that it will only allow of the concentration of troops to a certain degree; and as it must be considered in the choice of the line of operations, therefore it has an influence in determining the theatre of War.
(14) The subsistence for troops is provided, whenever the state of a country allows of it, at the cost of the country, by requisitions.
According to the present mode of making War, Armies take up considerably more space than formerly. The formation of separate independent corps has made this possible without our being placed at a disadvantage if opposed to an enemy who is concentrated in the old manner (with 70,000 to 100,000 men) at one spot; for one of these Corps, organised as they now are, can sustain itself for some time against an enemy twice or three times superior in numbers; during this time other Corps arrive, and therefore, even if this Corps is actually beaten, it will not have fought in vain, as we have already observed elsewhere.
Accordingly, now, single Divisions or Corps take the field, marching separately either in line with each other, or in succession one after another, and only so far in connection that, if they belong to the same Army, they can take part in any battle which may occur.
This makes it practicable to subsist an Army for a time without magazines. It is facilitated by the organisation of the Corps itself, by its staff and its commissariat department.
(15) When important reasons (as for instance the position of the enemy’s principal Army) do not decide otherwise, one should choose the richest and most productive provinces to operate in, for facility of subsistence promotes rapidity of movement. There is nothing which in importance surpasses the subsistence, except the position of the enemy’s principal Army, which we are seeking, the situation of the capital city, or strong place which we wish to take. All other considerations, for instance, the advantageous form of drawing up the armed force (order of battle), of which we have already spoken, are, as a rule, much less important.
(16) In spite of this new method of subsisting, we are very far from being able to dispense with all magazines, and a wise Commander, even if the resources of the province are quite sufficient, will not neglect to form magazines behind him as a provision against unforeseen events, and so as to be able the more readily to concentrate his strength at certain points. This is one of those measures of precaution which are no detriment to the main object.
(1) In political language, a defensive War is one which a State carries on to maintain its independence: in Strategy, a defensive War is a campaign in which we limit ourselves to contending with the enemy in a theatre of War which has been prepared by us for the purpose. Whether the battles we fight in this theatre of War are offensive or defensive makes no difference in this respect.
(2) We choose the strategic defensive chiefly when the enemy is superior in force. Naturally fortresses and entrenched camps, which are to be regarded as the chief preparations of a theatre of War, afford great advantages, to which may be added knowledge of the country and the possession of good maps and surveys. With these advantages, a small Army, or an Army which is based on a small State and limited resources, will be more in a condition to oppose the enemy than without the aid of such assistance.
There are besides the two following grounds upon which we may choose the defensive form of War by preference:
First.—If the poverty of the provinces surrounding our theatre of War makes our operations extremely difficult on account of the question of subsistence. In that case we escape the disadvantage, and the enemy must submit to it. This is, for instance, at this moment (1812) the case of the Russian Army.
Secondly.—If the enemy has greater advantages for carrying on the War. In a prepared theatre of War—which we know, where all the surrounding circumstances are in our favour—War is more easily conducted; there will not be so many faults committed. In this case, that is, when the little dependence to be placed on our troops and Generals compels us to resort to the defensive, we gladly combine the tactical defensive with the strategic, that is, we give battle in positions prepared beforehand; we do so further because there is less risk of our committing faults.
(3) In defensive War, just as much as in the offensive, a great object should be pursued. This can be nothing else than to annihilate the enemy’s Army, either in a battle, or by making his subsistence so difficult as to produce disorganisation and compel him to retreat, by which he must necessarily suffer considerable losses. Wellington’s campaign in the years 1810 and 1811 is an instance of this.
The defensive War, therefore, does not consist in an indolent waiting for events; we must only pursue the waiting-for system where there is a palpable and decisive utility in that mode of procedure. That sort of calm before a storm, whilst the offensive is gathering up new force for great blows, is extremely dangerous for the defender.
If the Austrians, after the battle of Aspern, had reinforced themselves to three times the strength of the French Emperor, which they certainly might have done, then the time of rest which took place before the battle of Wagram might have been advantageous to them, but only on that condition; as they did not do so, it was so much lost time for them, and it would have been wiser if they had taken advantage of Napoleon’s critical position to reap the fruits of their success at Aspern.
(4) Fortresses are intended to occupy an important part of the enemy’s Army in besieging them. This period must, therefore, be taken advantage of to beat the rest of the Army. Our battles should be fought behind our fortresses, not in front of them. At the same time, however, we must not quietly look on at their being captured, as Benningsen did during the siege of Dantzig.
(5) A great river, that is, one we cannot build a bridge across without considerable difficulty—rivers like the Danube below Vienna, and the Lower Rhine—affords a natural line of defence of which we can avail ourselves, not by distributing our forces equally along its banks, and seeking to hinder the passage absolutely, which is a dangerous measure, but by watching it, and when the enemy passes, then falling upon him from all sides just at the moment when he has not yet got all his forces under command, and is still hemmed in within a narrow space close to the river. The battle of Aspern is an instance. At the battle of Wagram the Austrians, without any necessity, allowed the French to get possession of far too much space, by which means they did away with the disadvantages peculiarly inherent to the passage of a river.
(6) Mountains are the second natural obstacles of ground which afford a good line of defence, as we can either have them in front, and only occupy them with a few light troops, treat them to a certain extent as a river which the enemy must cross, and as soon as he debouches with his single columns, fall upon one of them with our whole weight, or we may ourselves take position in the mountains. In the last case, we must only defend the single passes with small detachments, and a considerable part of the Army (a third or a half) must remain in reserve, in order to fall in superior numbers on any column which forces its way through. This great reserve must, however, not be split up with a view to absolutely preventing all the columns from passing, but we must, from the first, resolve to make use of it to attack that column which we suppose to be the strongest. If, in this way, we rout a considerable part of the enemy’s force, the other columns which have forced their way through will of themselves retire again.
The formation of mountain ranges in general is such that about the centre of the masses there are plateaux or plains at a greater or less elevation, and the sides next to the level country are intersected by deep valleys forming the entrances or avenues. The defender, therefore, has in the mountains a district in which he can make rapid movements right or left, whilst the attacking columns are separated from each other by steep, inaccessible ridges. It is only a mountain mass of this kind that is well adapted for a good defence. If it is rugged and impassable generally throughout, so that the Corps on the defensive must be scattered and disconnected, then to undertake the defence with the principal Army is a dangerous measure, for under such circumstances all the advantages are on the side of the assailant, who can fall upon any of the isolated posts with far superior numbers, as no pass, no single post is so strong that it cannot soon be taken by superior numbers.
(7) With regard to mountain warfare, it is specially to be observed that in it a great deal depends on the aptitude of subordinate officers, but still more on the high spirit which animates the ranks. Great skill in manœuvring is not here requisite, but a military spirit and a heart in the cause, for every one is more or less left to act independently; this is why national levies find their account in mountain warfare, for while they are deficient in the first quality, they possess the other in the highest degree.
(8) Lastly, in respect to the strategic defensive, it is to be observed that, while it is in itself stronger than the offensive, it should only be used to gain the first great result, and that if this object is attained, and peace does not immediately follow upon that, greater results can only be obtained by the offensive; for whoever remains always on the defensive exposes himself to the disadvantage of always carrying on the War at his own expense. No State can endure that for more than a certain time; and therefore, if it exposes itself to the blows of its adversary without ever striking in return, it is almost sure in the end to become exhausted, and be obliged to submit. We should therefore begin with the defensive, that we may with the more certainty end with the offensive.
(1) The strategic attack pursues the aim of the War directly, for it is aimed directly at the destruction of the enemy’s armed force, whilst the strategic defence seeks to obtain this object partly only indirectly. From this it comes that the principles of the attack are already contained in the general principles of Strategy. Only two subjects require special mention.
(2) The first is, keeping the Army constantly complete in men and arms. To the defender, this is relatively easier, from the proximity of his resources. The assailant, although in most cases possessed of the resources of a powerful State, must bring his means more or less from a distance, and therefore, of course, with greater difficulty. That he may not run short in means, he must make such arrangements that the levy of recruits and transport of arms anticipate his wants in these respects. The roads on his line of operations must be incessantly covered with reinforcements and trains of supplies moving to the front; on those roads, military stations must be formed to expedite the transport.
(3) Even in the most prosperous circumstances, and with the greatest moral and physical superiority, the assailant must keep in view the possibility of a great change of fortune. For this reason, he must provide points on the line of operations suitable for refuge, in the event of his Army being beaten. Such are fortresses with entrenched camps, or simply entrenched camps.
Large rivers afford the best means of checking the pursuit of an enemy for a time. We should therefore secure the passages across them with bridge heads, surrounded with a girdle of strong redoubts.
For the defence of these points, and as garrisons for important towns and fortresses, troops, in greater or less number, must be left behind, according as we have to apprehend attacks from the enemy or the hostility of the inhabitants of the country. These, with the reinforcements coming up, form new Corps, which, in case of success, follow the Army, but in case of disaster are stationed at the points which have been fortified to secure the retreat.
Napoleon always showed great foresight in the provision he made in this manner in the rear of his Army; and in that way, even in his boldest operations, he incurred less risks than might be imagined at first sight.