EVERY position in which we accept battle, at the same time making use of the ground as a means of protection, is a defensive position, and it makes no difference in this respect whether we act more passively or more offensively in the action. This follows from the general view of the defensive which we have given.
Now we may also apply the term to every position in which an army whilst marching to encounter the enemy would certainly accept battle if the latter sought for it. In point of fact, most battles take place in this way, and in all the middle ages no other was ever thought of. That is, however, not the kind of position of which we are now speaking; by far the greater number of positions are of this kind, and the conception of a position in contradistinction to a camp taken up on the march would suffice for that. A position which is specially called a defensive position must therefore have some other distinguishing characteristics.
In the decisions which take place in an ordinary position, the idea of time evidently predominates; the armies march against each other in order to come to an engagement: the place is a subordinate point, all that is required from it is that it should not be unsuitable. But in a real defensive position the idea of place predominates; the decision is to be realised on this spot, or rather, chiefly through this spot. That is the only kind of position we have here in view.
Now the connection of place is a double one; that is, in the first instance, inasmuch as a force posted at this point exercises a certain influence upon the war in general; and next, inasmuch as the local features of the ground contribute to the strength of the army and afford protection: in a word, a strategic and a tactical connection.
Strictly speaking, the term defensive position has its origin only in connection with tactics, for its connection with strategy, namely, that an army posted at this point by its presence serves to defend the country, will also suit the case of an army acting offensively.
The strategic effect to be derived from a position cannot be shown completely until hereafter, when we discuss the defence of a theatre of war; we shall therefore only consider it here as far as can be done at present, and for that end we must examine more closely the nature of two ideas which have a similarity and are often mistaken for one another, that is, the turning a position, and the passing by it.
The turning a position relates to its front, and is done either by an attack upon the side of the position or on its rear, or by acting against its lines of retreat and communication.
The first of these, that is, an attack on flank or rear is tactical in its nature. In our days in which the mobility of troops is so great, and all plans of battles have more or less in view the turning or enveloping the enemy, every position must accordingly be adapted to meet such measures, and one to deserve the name of strong must, with a strong front, allow at least of good combinations for battle on the sides and rear as well, in case of their being menaced. In this way a position will not become untenable by the enemy turning it with a view to an attack on the flank or rear, as the battle which then takes place was provided for in the choice of the position, and should ensure the defender all the advantages which he could expect from this position generally.
If the position is turned by the enemy with a view to acting against the lines of retreat and communication, this is a strategic relation, and the question is how long the position can be maintained, and whether we cannot outbid the enemy by a scheme like his own, both these questions depend on the situation of the point (strategically), that is, chiefly on the relations of the lines of communication of both combatants. A good position should secure to the army on the defensive the advantage in this point. In any case the position will not be rendered of no effect in this way, as the enemy is neutralised by the position when he is occupied by it in the manner supposed.
But if the assailant, without troubling himself about the existence of the army awaiting his attack in a defensive position, advances with his main body by another line in pursuit of his object, then he passes by the position; and if he can do this with impunity, and really does it, he will immediately enforce the abandonment of the position, consequently put an end to its usefulness.
There is hardly any position in the world which, in the simple sense of the words, cannot be passed by, for cases such as the isthmus of Perekop are so rare that they are hardly worth attention. The impossibility of passing by must therefore be understood as merely applying to the disadvantages in which the assailant would become involved if he set about such an operation. We shall have a more fitting opportunity to state these disadvantages in the twenty-seventh chapter; whether small or great, in every case they are the equivalent of the tactical effect which the position is capable of producing but which has not been realised, and in common with it constitute the object of the position.
From the preceding observations, therefore, two strategic properties of the defensive position have resulted:
1. That it cannot be passed round.
2. That in the struggle for the lines of communication it gives the defender advantages.
Here we have to add two other strategic properties, namely—
3. That the relation of the lines of communication may also have a favourable influence on the form of combat; and
4. That the general influence of the country is advantageous.
For the relation of the lines of communication has an influence not only upon the possibility or impossibility of passing by a position or of cutting off the enemy's supplies, but also on the whole course of the battle. An oblique line of retreat facilitates a tactical turning movement on the part of the assailant, and paralyses our own tactical movements during the battle. But an oblique position in relation to the lines of communication is often not the fault of tactics but a consequence of a defective strategic point; it is, for example, not to be avoided when the road changes direction in the vicinity of the position (Borodino, 1812); the assailant is then in such a position that he can turn our line without deviating from, his own perpendicular disposition.
Further, the aggressor has much greater freedom for tactical movement if he commands several roads for his retreat whilst we are limited to one. In such cases the tactical skill of the defensive will be exerted in vain to overcome the disadvantageous influence resulting from the strategic relations.
Lastly as regards the fourth point, such a disadvantageous general influence may predominate in the other characteristics of ground, that the most careful choice, and the best use of tactical means, can do nothing to combat them. Under such circumstances the chief points are as follows:
1. The defensive must particularly seek for the advantage of being able to overlook his adversary, so that he may be able swiftly to throw himself upon him inside the limits of his position. It is only when the local difficulties of approach combine with these two conditions that the ground is really favourable to the defensive.
On the other hand, those points which are under the influence of commanding ground are disadvantageous to him; also most positions in mountains (of which we shall speak more particularly in the chapters on mountain warfare). Further, positions which rest one flank on mountains, for such a position certainly makes the passing by more difficult, but facilitates a turning movement. Of the same kind are all positions which have a mountain immediately in their front, and generally all those which bear relation to the description of ground above specified.
As an example of the opposite of these disadvantageous properties, we shall only instance the case of a position which has a mountain in rear; from this so many advantages result that it may be assumed in general to be one of the most favourable of all positions for the defensive.
2. A country may correspond more or less to the character and composition of an army. A very numerous cavalry is a proper reason for seeking an open country. Want of this arm, perhaps also of artillery, while we have at command a courageous infantry inured to war, and acquainted with the country, make it advisable to take advantage of a difficult, close country.
We do not here enter into particulars respecting the tactical relation which the local features of a defensive position bear to the force which is to occupy it. We only speak of the total result, as that only is a strategic quantity.
Undoubtedly a position in which an army is to await the full force of the hostile attack, should give the troops such an important advantage of ground as may be considered a multiplier of its force. Where nature does much, but not to the full as much as we want, the art of entrenchment comes to our help. In this way it happens not unfrequently that some parts become unassailable, and not unusually the whole is made so: plainly in this last case, the whole nature of the measure is changed. It is then no longer a battle under advantageous conditions which we seek, and in this battle the issue of the campaign, but an issue without a battle. Whilst we occupy with our force an unassailable position, we directly refuse the battle, and oblige our enemy to seek for a solution in some other way.
We must, therefore, completely separate these two cases, and shall speak of the latter in the following chapter, under the title of a strong position.
But the defensive position with which we have now to do is nothing more than a field of battle with the addition of advantages in our favour; and that it should become a field of battle, the advantages in our favour must not be too great. But now what degree of strength may such a position have? Plainly more in proportion as our enemy is more determined on the attack, and that depends on the nature of the individual case. Opposed to a Buonaparte, we may and should withdraw behind stronger ramparts than before a Daun or a Schwartzenburg.
If certain portions of a position are unattackable, say the front, then that is to be taken as a separate factor of its whole strength, for the forces not required at that point are available for employment elsewhere; but we must not omit to observe that whilst the enemy is kept completely off such impregnable points, the form of his attack assumes quite a different character, and we must ascertain, in the first instance, how this alteration will suit our situation.
For instance, to take up a position, as has often been done, so close behind a great river that it is to be looked upon as covering the front, is nothing else but to make the river a point of support for the right or left flank; for the enemy is naturally obliged to cross further to the right or left, and cannot attack without changing his front: the chief question, therefore, is what advantages or disadvantages does that bring to us?
According to our opinion, a defensive position will come the nearer to the true ideal of such a position the more its strength is hid from observation, and the more it is favourable to our surprising the enemy by our combinations in the battle. Just as we advisably endeavour to conceal from the enemy the whole strength of our forces and our real intentions, so in the same way we should seek to conceal from the enemy the advantages which we expect to derive from the form of the ground. This of course can only be done to a certain degree, and requires, perhaps, a peculiar mode of proceeding, hitherto but little attempted.
The vicinity of a considerable fortress, in whatever direction it may be, confers on every position a great advantage over the enemy in the movement and use of the forces belonging to it. By suitable field-works, the want of natural strength at particular points may be remedied, and in that manner the great features of the battle may be settled beforehand at will; these are the means of strengthening by art; if with these we combine a good selection of those natural obstacles of ground which impede the effective action of the enemy's forces without making action absolutely impossible, if we turn to the best account the advantage we have over the enemy in knowing the ground, which he does not, so that we succeed in concealing our movements better than he does his, and that we have a general superiority over him in unexpected movements in the course of the battle, then from these advantages united, there may result in our favour an overpowering and decisive influence in connection with the ground, under the power of which the enemy will succumb, without knowing the real cause of his defeat. This is what we understand under defensive position, and we consider it one of the greatest advantages of defensive war.
Leaving out of consideration particular circumstances, we may assume that an undulating, not too well, but still not too little, cultivated country affords the most positions of this kind.