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.
If there is no great object within the assailant's sphere of victory, then the enemy's line of communication with the nearest great object to him is the point of paramount importance. The question, then, for every assailant to ask himself is, If I am successful in the battle, what is the first use I shall make of the victory? The object to be gained, as indicated by the answer to this question, shows the natural direction for his blow. If the defender has placed himself in that direction, he has done right, and there is nothing to do but to go and look for him there. If his position is too strong, then the assailant must seek to turn it, that is, make a virtue of necessity. But if the defender has not placed himself on this right spot, then the assailant chooses that direction, and as soon as he comes in line with the defender, if the latter has not in the mean time made a lateral movement, and placed himself across his path, he should turn himself in the direction of the defender's line of communication in order to seek an action there; if the defender remains quite stationary, then the assailant must wheel round towards him and attack him in rear.
Of all the roads amongst which the assailant has a choice, the great roads which serve the commerce of the country are always the best and the most natural to choose. To avoid any very great bends, more direct roads, even if smaller, must be chosen, for a line of retreat which deviates much from a direct line is always perilous.
5. The assailant, when he sets out with a view to a great decision, has seldom any reason for dividing his forces, and if, notwithstanding this, he does so, it generally proceeds from a want of clear views. He should therefore only advance with his columns on such a width of front as will admit of their all coming into action together. If the enemy himself has divided his forces, so much the better for the assailant, and to preserve this further advantage small demonstrations should be made against the enemy's corps which have separated from the main body; these are the strategic fausses attaques; a detachment of forces for this purpose would then be justifiable.
Such separation into several columns as is indispensably necessary must be made use of for the disposition of the tactical attack in the enveloping form, for that form is natural to the attack, and must not be disregarded without good reason. But it must be only of a tactical nature, for a strategic envelopment when a great blow takes place, is a complete waste of power. It can only be excused when the assailant is so strong that there can be no doubt at all about the result.
6. But the attack requires also prudence, for the assailant has also a rear, and has communications which must be protected. This service of protection must be performed as far as possible by the manner in which the army advances, that is, eo ipso by the army itself. If a force must be specially detailed for this duty, and therefore a partition of forces is required, this cannot but naturally weaken the force of the blow itself.—As a large army is always in the habit of advancing with a front of a day's march at least in breadth, therefore, if the lines of retreat and communication do not deviate much from the perpendicular, the covering of those lines is in most cases attained by the front of the army.
Dangers of this description, to which the assailant is exposed, must be measured chiefly by the situation and character of the adversary. When everything lies under the pressure of an imminent great decision, there is little room for the defender to engage in undertakings of this description; the assailant has, therefore, in ordinary circumstances not much to fear. But if the advance is over, if the assailant himself is gradually passing into the defensive, then the covering of the rear becomes every moment more necessary, becomes more a thing of the first importance. For the rear of the assailant being naturally weaker than that of the defender, therefore the latter, long before he passes over to the real offensive, and even at the same time that he is yielding ground, may have commenced to operate against the communications of the assailant.