But now, if cutting off the enemy’s retreat is not to be a mere demonstration, but is seriously intended, the real solution is a decisive battle, or, at least, the conjunction of all the conditions for the same; and just in this solution we find again the two elements above-mentioned—the greater result and the greater danger. Therefore, if a general is to stand justified in adopting this method of action, his reasons must be favourable conditions.
In this method of resistance we must distinguish the two forms already mentioned. The first is, if a general with his whole force intends to attack the enemy in rear, either from a position taken up on the flank for that purpose, or by a formal turning movement; the second is, if he divides his forces, and, by an enveloping position with one part, threatens the enemy’s rear, with the other part his front.
The result is intensified in both cases alike, that is—either there is a real interception of the retreat, and consequently the enemy’s army taken prisoners, or the greater part scattered, or there may be a long and hasty retreat of the enemy’s force to escape the danger.
But the intensified risk is different in the two cases.
If we turn the enemy with our whole force, the danger lies in the laying open our own rear; and hence the question again depends on the relation of the mutual lines of retreat, just as in the action against the lines of communication, it depended on the relation of those lines.
Now certainly the defender, if he is in his own country, is less restricted than the assailant, both as to his lines of retreat and communication, and in so far is therefore in a better position to turn his adversary strategically; but this general relation is not of a sufficiently decisive character to be used as the foundation of a practical method; therefore, nothing but the whole of the relations in each individual case can decide.
Only so much we may add, that favourable conditions are naturally more common in wide spheres of action than in small; more common, also, on the side of independent states than on that of weak ones, dependent on foreign aid, and whose armies must, therefore, constantly have their attention bent on the point of junction with the auxiliary army; lastly, they become most favorable for the defender towards the close of the campaign, when the impulsive force of the assailant is somewhat spent; very much, again, in the same manner as in the case of the lines of communication.
Such a flank position as the Russians took up with such advantage on the road from Moscow to Kaluga, when Buonaparte’s aggressive force was spent, would have brought them into a scrape at the commencement of the campaign at the camp of Drissa, if they had not been wise enough to change their plan in good time.
The other method of turning the enemy, and cutting off his retreat by dividing our force, entails the risk attending a division of our own force, whilst the enemy, having the advantage of interior lines, retains his forces united, and therefore has the power of acting with superior numbers against one of our divisions. This is a disadvantage which nothing can remove, and in exposing ourselves to it, we can only be justified by one of three principal reasons:—
1. The original division of the force which makes such a method of action necessary, unless we incur a great loss of time.