on several occasions, still the mere fact of its being in a general way one of the means of reaching this solution, would be sufficient to enjoin the greatest concentration of our forces which circumstances will in any way permit. A great battle upon the theatre of war is the blow of the centre of force against the centre of force; the more forces can be collected in the one or the other, the surer and greater will be the effect. Therefore every separation of forces which is not called for by an object (which either cannot itself be attained by the successful issue of a battle, or which itself is necessary to the successful issue of the battle) is blameable .
But the greatest concentration of forces is not the only fundamental condition; it is also requisite that they should have such a position and place that the battle may be fought under favourable circumstances.
The different steps in the defence which we have become acquainted with in the chapter on the methods of defence, are completely homogeneous with these fundamental conditions; there will therefore be no difficulty in connecting them with the same, according to the special requirements of each case. But there is one point which seems at first sight to involve a contradiction in itself, and which, as one of the most important in the defence, requires explanation so much the more. It is the hitting upon the exact centre of gravity of the enemy’s force.
If the defender ascertains in time the roads by which the enemy will advance, and upon which in particular the great mass of his force will be found for a certainty, he may march against him on that road. This will be the most usual case, for although the defence precedes the attack in measures of a general nature, in the establishment of strong places, great arsenals, and depôts, and in the peace establishment of his army, and thus gives a line of direction to the assailant in his preparations, still, when the campaign really opens, the defender, in relation to the aggressor, has the peculiar advantage in general of playing the last hand.