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—