On War

by Carl von Clausewitz

Morasses, that is, impassable swamps, which are only traversed by a few embankments, present peculiar difficulties to the tactical attack, as we have stated in treating of the defence. Their breadth hardly ever admits of the enemy being driven from the opposite bank by artillery, and of the construction of a roadway across. The strategic consequence is that endeavours are made to avoid attacking them by passing round them. Where the state of culture, as in many low countries, is so great that the means of passing are innumerable, the resistance of the defender is still strong enough relatively, but it is proportionably weakened for an absolute decision, and, therefore, wholly unsuitable for it. On the other hand, if the low land (as in Holland) is aided by inundations, the resistance may become absolute, and defy every attack. This was shown in Holland in the year 1672, when, after the conquest and occupation of all the fortresses outside the margin of the inundation, 50,000 French troops became available, who,—first under Condé and then under Luxemburg,—were unable to force the line of inundation, although it was only defended by about 20,000 men. The campaign of the Prussians, in 1787, under the Duke of Brunswick, against the Dutch, ended, it is true, in a quite contrary way, as these lines were then carried by a force very little superior to the defenders, and with trifling loss; but the reason of that is to be found in the dissensions amongst the defenders from political animosities, and a want of unity in the command, and yet nothing is more certain than that the success of the campaign, that is, the advance through the last line of inundation up to the walls of Amsterdam depended on a point of such extreme nicety that it is impossible to draw any general deduction from this case. The point alluded to was the leaving unguarded the Sea of Haarlem. By means of this, the Duke turned the inundation line, and got in rear of the post of Amselvoen. If the Dutch had had a couple of armed vessels on this lake the duke would never have got to Amsterdam, for he was “au bout de son latin.” What influence that might have had on the conclusion of peace does not concern us here, but it is certain that any further question of carrying the last line of inundation would have been put an end to completely.

The winter is, no doubt, the natural enemy of this means of defence, as the French have shown in 1794 and 1795, but it must be a severe winter.

Woods, which are scarcely passable, we have also included amongst the means which afford the defence powerful assistance. If they are of no great depth then the assailant may force his way through by several roads running near one another, and thus reach better ground, for no one point can have any great tactical strength, as we can never suppose a wood as absolutely impassable as a river or a morass.—But when, as in Russia and Poland, a very large tract of country is nearly everywhere covered with wood, and the assailant has not the power of getting beyond it, then, certainly, his situation becomes very embarrassing. We have only to think of the difficulties he must contend with to subsist his army, and how little he can do in the depths of the forest to make his ubiquitous adversary feel his superiority in numbers. Certainly this is one of the worst situations in which the offensive can be placed.

CHAPTER XV.
Attack on a Theatre of War with the View to a Decision

Most of the subjects have been already touched upon in the sixth book, and by their mere reflection, throw sufficient light on the attack.

Moreover, the conception of an enclosed theatre of war, has a nearer relation to the defence than to the attack. Many of the leading points, the object of attack, the sphere of action of victory, etc., have been already treated of in that book, and that which is most decisive and essential on the nature of the attack, cannot be made to appear until we get to the plan of war: still there remains a good deal to say here, and we shall again commence with the campaign, in which a great decision is positively intended.

1. The first aim of the attack is a victory. To all the advantages which the defender finds in the nature of his situation, the assailant can only oppose superior numbers; and, perhaps, in addition, the slight advantage which the feeling of being the offensive and advancing side gives an army. The importance of this feeling, however, is generally overrated; for it does not last long, and will not hold out against real difficulties. Of course, we assume that the defender is as faultless and judicious in all he does as the aggressor. Our object in this observation is to set aside those vague ideas of sudden attack and surprise, which, in the attack, are generally assumed to be fertile sources of victory, and which yet, in reality, never occur except under special circumstances. The nature of the real strategic surprise, we have already spoken of elsewhere.—If, then, the attack is inferior in physical power, it must have the ascendancy in moral power, in order to make up for the disadvantages which are inherent in the offensive form; if the superiority in that way is also wanting, then there are no good grounds for the attack, and it will not succeed.

2. As prudence is the real genius of the defender, so boldness and self-confidence must animate the assailant. We do not mean that the opposite qualities in each case may be altogether wanting, but that the qualities named have the greatest affinity to the attack and defence respectively. These qualities are only in reality necessary because action in war is no mere mathematical calculation; it is activity which is carried on if not in the dark, at all events in a feeble twilight, in which we must trust ourselves to the leader who is best suited to carry out the aim we have in view.—The weaker the defender shows himself morally, the bolder the assailant should become.

3. For victory, it is necessary that there should be a battle between the enemy’s principal force and our own. This is less doubtful as regards the attack than in regard to the defence, for the assailant goes in search of the defender in his position. But we have maintained (in treating of the defensive) that the offensive should not seek the defender out if he has placed himself in a false position, because he may be sure that the defender will seek him out, and then he will have the advantage of fighting where the defender has not prepared the ground. Here all depends on the road and direction which have the greatest importance; this is a point which was not examined in the defence, being reserved for the present chapter. We shall, therefore, say what is necessary about it here.

4. We have already pointed out those objects to which the attack should be more immediately directed, and which, therefore, are the ends to be obtained by victory; now, if these are within the theatre of war which is attacked, and within the probable sphere of victory, then the road to them is the natural direction of the blow to be struck. But we must not forget that the object of the attack does not generally obtain its signification until victory has been gained, and therefore the mind must always embrace the idea of victory with it; the principal consideration for the assailant is, therefore, not so much merely to reach the object as to reach it a conqueror; therefore the direction of his blow should be not so much on the object itself as on the way which the enemy’s army must take to reach it. This way is the immediate object of the attack. To fall in with the enemy before he has reached this object, to cut him off from it, and in that position to beat him—to do this is to gain an intensified victory.—If, for example, the enemy’s capital is the object of the attack, and the defender has not placed himself between it and the assailant, the latter would be wrong in marching direct upon the capital, he would do much better by taking his direction upon the line connecting the defender’s army with the capital, and seeking there the victory which shall place the capital in his hands.