Incursions into the enemy’s country which have as their object reprisals or levying contributions, cannot properly be regarded as defensive means, they are rather true offensive means; but they are usually combined with the object of a real diversion, which may be regarded as a real defensive measure, as it is intended to weaken the enemy’s force opposed to us. But as the above means may be used just as well by the assailant, and in itself is a real attack, we therefore think more suitable to leave its further examination for the next book. Accordingly we shall only count it in here, in order to render a full account of the arsenal of small offensive arms belonging to the defender of a theatre of war, and for the present merely add that in extent and importance it may attain to such a point, as to give the whole war the appearance, and along with that the honour, of the offensive. Of this nature are Frederick the Great’s enterprises in Poland, Bohemia and Franconia, before the campaign of 1759. His campaign itself is plainly a pure defence; these incursions into the enemy’s territory, however, gave it the appearance of an aggression, which perhaps had a special value on account of the moral effect.
An attack on one of the enemy’s corps or on his main body must always be kept in view as a necessary complement of the whole defence whenever the aggressor takes the matter too easily, and on that account shows himself very defenceless at particular points. Under this silent condition the whole action takes place. But here also the defender, in the same way as in operating against the communications of the enemy, may go a step further in the province of the offensive, and just as well as his adversary may make it his business to lie in wait for a favourable stroke. In order to ensure a result in this field, he must either be very decidedly superior in force to his opponent—which certainly is inconsistent with the defensive in general, but still may happen—or he must have a method and the talent of keeping his forces more concentrated, and make up by activity and mobility for the danger which he incurs in other respects.