We have not treated of this subject in the defence, because a line of cantonments is not to be regarded as a defensive means, but as a mere existence of the army in a state which implies little readiness for battle. In respect to this readiness for battle, we therefore did not go beyond what we required to say in connection with this condition of an army in the 13th chapter of the 5th book.
But here, in considering the attack, we have to think of an enemy’s army in cantonments in all respects as a special object; for, in the first place, such an attack is of a very peculiar kind in itself; and, in the next place, it may be considered as a strategic means of particular efficacy. Here we have before us, therefore, not the question of an onslaught on a single cantonment or a small corps dispersed amongst a few villages, as the arrangements for that are entirely of a tactical nature, but of the attack of a large army, distributed in cantonments more or less extensive; an attack in which the object is not the mere surprise of a single cantonment, but to prevent the assembly of the army.
The attack on an enemy’s army in cantonments is therefore the surprise of an army not assembled. If this surprise succeeds fully, then the enemy’s army is prevented from reaching its appointed place of assembly, and, therefore, compelled to choose another more to the rear; as this change of the point of assembly to the rear in a state of such emergency can seldom be effected in less than a day’s march, but generally will require several days, the loss of ground which this occasions is by no means an insignificant loss; and this is the first advantage gained by the assailant.