The superiority which we have attributed to the defensive form of war consists:
1. In the use of ground.
2. In the possession of a prepared theatre of war.
3. In the support of the people.
4. In the advantage of the state of expectancy.
It must be evident that these principles cannot always be forthcoming and active in a like degree; that, consequently, one defence is not always like another; and therefore, also, that the defence will not always have this same superiority over the offensive. This must be particularly the case in a defensive, which commences after the exhaustion of an offensive, and has its theatre of war usually situated at the apex of an offensive triangle thrust far forward into the country. Of the four principles above named, this defensive only enjoys the first the use of the ground undiminished, the second generally vanishes altogether, the third becomes negative, and the fourth is very much reduced. A few more words, only by way of explanation, respecting the last.
If the imagined equilibrium, under the influence of which whole campaigns have often passed without any results, because the side which should assume the initiative is wanting in the necessary resolution, and just therein lies, as we conceive, the advantage of the state of expectancy if this equilibrium is disturbed by an offensive act, the enemy’s interests damaged, and his will stirred up to action, then the probability of his remaining in a state of indolent irresolution is much diminished. A defence, which is organised on conquered territory, has a much more irritating character than one upon our own soil; the offensive principle is engrafted on it in a certain measure, and its nature is thereby weakened. The quiet which Daun allowed Frederick II. in Silesia and Saxony, he would never have granted him in Bohemia.
Thus it is clear that the defensive, which is interwoven or mixed up with an offensive undertaking, is weakened in all its chief principles; and, therefore, will no longer have the preponderance which belongs to it originally.
As no defensive campaign is composed of purely defensive elements, so likewise no offensive campaign is made up entirely of offensive elements; because, besides the short intervals in every campaign, in which both armies are on the defensive, every attack which does not lead to a peace, must necessarily end in a defensive.
In this manner it is the defensive itself which contributes to the weakening of the offensive. This is so far from being an idle subtlety, that on the contrary, we consider it a chief disadvantage of the attack that we are afterwards reduced through it to a very disadvantageous defensive.