Front Page Titles (by Subject) CHAPTER III: THE RELATIONS OF THE OFFENSIVE AND DEFENSIVE TO EACH OTHER IN STRATEGY - On War, vol. 2
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CHAPTER III: THE RELATIONS OF THE OFFENSIVE AND DEFENSIVE TO EACH OTHER IN STRATEGY - Carl von Clausewitz, On War, vol. 2 
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. 2.
Part of: On War
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THE RELATIONS OF THE OFFENSIVE AND DEFENSIVE TO EACH OTHER IN STRATEGY
Let us ask again, first of all, what are the circumstances which ensure a successful result in Strategy?
In Strategy there is no victory, as we have before said. On the one hand, the strategic success is the successful preparation of the tactical victory; the greater this strategic success, the more probable becomes the victory in the battle. On the other hand, strategic success lies in the making use of the victory gained. The more events the strategic combinations can in the sequel include in the consequences of a battle gained, the more Strategy can lay hands on amongst the wreck of all that has been shaken to the foundation by the battle, the more it sweeps up in great masses what of necessity has been gained with great labour by many single hands in the battle, the grander will be its success. Those things which chiefly lead to this success, or at least facilitate it, consequently the leading principles of efficient action in Strategy, are as follow:—
1. The advantage of ground.
2. The surprise, let it be either in the form of an actual attack by surprise or by the unexpected display of large forces at certain points.
3. The attack from several quarters (all three, as in tactics).
4. The assistance of the theatre of War by fortresses, and everything belonging to them.
5. The support of the people.
6. The utilisation of great moral forces.
Now, what are the relations of offensive and defensive with respect to these things?
The Defender has the advantage of ground; the Assailant that of the attack by surprise in Strategy, as in tactics. But respecting the surprise, we must observe that it is infinitely more efficacious and important in the former than in the latter. In tactics, a surprise seldom rises to the level of a great victory, while in Strategy it often finishes the war at one stroke. But at the same time we must observe that the advantageous use of this means supposes some great and uncommon, as well as decisive error committed by the adversary, therefore it does not alter the balance much in favour of the offensive.
The surprise of the enemy, by placing superior forces in position at certain points, has again a great resemblance to the analogous case in tactics. Were the defensive compelled to distribute his forces upon several points of approach to his theatre of War, then the offensive would have plainly the advantage of being able to fall upon one point with all his weight. But here also, the new art of acting on the defensive by a different mode of proceeding has imperceptibly brought about new principles. If the defender does not apprehend that the enemy, by making use of an undefended road, will throw himself upon some important magazine or depôt, or on some unprepared fortification, or on the capital itself,—and if he is not reduced to the alternative of opposing the enemy on the road he has chosen, or of having his retreat cut off, then there are no peremptory grounds for dividing his forces; for if the offensive chooses a different road-from that on which the defensive is to be found, then some days later the latter can march against his opponent with his whole force upon the road he has chosen; besides, he may at the same time, in most cases, rest satisfied that the offensive will do him the honour to seek him out.* —If the offensive is obliged to advance with his forces divided, which is often unavoidable on account of subsistence, then plainly the defensive has the advantage on his side of being able to fall in force upon a fraction of the enemy.
Attacks in flank and rear, which in Strategy mean on the sides and reverse of the theatre of War, are of a very different nature to attacks so called in tactics.
1st. There is no bringing the enemy under two fires, because we cannot fire from one end of a theatre of War to the other.
2nd. The apprehension of losing the line of retreat is very much less, for the spaces in Strategy are so great that they cannot be barred as in tactics.
3rd. In Strategy, on account of the extent of space embraced, the efficacy of interior, that is of shorter lines, is much greater, and this forms a great safeguard against attacks from several directions.
4th. A new principle makes its appearance in the sensibility, which is felt as to lines of communication, that is in the effect which is produced by merely interrupting them.
Now it confessedly lies in the nature of things, that on account of the greater spaces in Strategy, the enveloping attack, or the attack from several sides, as a rule is only possible for the side which has the initiative, that is the offensive, and that the defensive is not in a condition, as he is in tactics, in the course of the action, to turn the tables on the enemy by surrounding him, because he has it not in his power either to draw up his forces with the necessary depth relatively, or to conceal them sufficiently: but then, of what use is the facility of enveloping to the offensive, if its advantages are not forthcoming? We could not therefore bring forward the enveloping attack in Strategy as a principle of victory in general, if its influence on the lines of communication did not come into consideration. But this factor is seldom great at the first moment, when attack and defence first meet, and while they are still opposed to each other in their original position; it only becomes great as a campaign advances, when the offensive in the enemy’s country is by degrees brought into the condition of defensive; then the lines of communication of this new party acting on the defensive, become weak, and the party originally on the defensive, in assuming the offensive can derive advantage from this weakness. But who does not see that this casual superiority of the attack is not to be carried to the credit of the offensive in general, for it is in reality created out of the superior relations of the defensive.
The fourth principle, the Assistance of the Theatre of War, is naturally an advantage on the side of the defensive. If the attacking Army opens the campaign, it breaks away from its own theatre, and is thus weakened, that is, it leaves fortresses and depôts of all kinds behind it. The greater the sphere of operations which must be traversed, the more it will be weakened (by marches and garrisons); the Army on the defensive continues to keep up its connection with everything, that is, it enjoys the support of its fortresses, is not weakened in any way, and is near to its sources of supply.
The support of the population as a fifth principle is not realised in every defence, for a defensive campaign may be carried on in the enemy’s country, but still this principle is only derived from the idea of the defensive, and applies to it in the majority of cases. Besides by this is meant chiefly, although not exclusively, the effect of calling out the last reserves, and even of a national armament, the result of which is that all friction is diminished, and that all resources are sooner forthcoming and flow in more abundantly.
The campaign of 1812, gives as it were in a magnifying glass a very clear illustration of the effect of the means specified under principles 3 and 4. 500,000 men passed the Niemen, 120,000 fought at Borodino, and much fewer arrived at Moscow.
We may say that the effect itself of this stupendous attempt was so disastrous that even if the Russians had not assumed any offensive at all, they would still have been secure from any fresh attempt at invasion for a considerable time. It is true that with the exception of Sweden there is no country in Europe which is situated like Russia, but the efficient principle is always the same, the only distinction being in the greater or less degree of its strength.
If we add to the fourth and fifth principles, the consideration that these forces of the defensive belong to the original defensive, that is the defensive carried on in our own soil, and that they are much weaker if the defence takes place in an enemy’s country and is mixed up with an offensive undertaking, then from that there is a new disadvantage for the offensive, much the same as above, in respect to the third principle; for the offensive is just as little composed entirely of active elements, as the defensive of mere warding off blows; indeed every attack which does not lead directly to peace must inevitably end in the defensive.
Now, if all defensive elements which are brought into use in the attack are weakened by its nature, that is by belonging to the attack, then this must also be considered as a general disadvantage of the offensive.
This is far from being an idle piece of logical refinement, on the contrary we should rather say that in it lies the chief disadvantage of the offensive in general, and therefore from the very commencement of, as well as throughout every combination for a strategic attack, most particular attention ought to be directed to this point, that is to the defensive, which may follow, as we shall see more plainly when we come to the book on plans of campaigns.
The great moral forces which at times saturate the being of War, as it were with a leaven of their own, which therefore the Commander in certain cases can use to assist the other means at his disposal, are to be supposed as much on the side of the defensive as of the offensive; at least those which are more especially in favour of the attack, such as confusion and disorder in the enemy’s ranks—do not generally appear until after the decisive stroke is given, and consequently seldom contribute beforehand to produce that result.
We think we have now sufficiently established our proposition, that the defensive is a stronger form of war than the offensive;* but there still remains to be mentioned one small factor hitherto unnoticed. It is the high spirit, the feeling of superiority in an Army which springs from a consciousness of belonging to the attacking party. The thing is in itself a fact, but the feeling soon merges into the more general and more powerful one which is imparted by victory or defeat, by the talent or incapacity of the General.
[* ]This is exactly what Napoleon did not do either at Jena or Friedland. By threatening an important point he compelled his adversary to interpose to protect it.—Ed.
[* ]Nowadays the fact that the defender in his own country has control over his railways may add enormously to his power. Thus in England it would be possible to transfer 200,000 men in twenty-four hours from Scotland to the South or vice versâ with ease.—Ed.