According to the ordinary use of language, under the term diversion is understood such an incursion into the enemy’s country as draws off a portion of his force from the principal point. It is only when this is the chief end in view, and not the gain of the object which is selected as the point of attack, that it is an enterprise of a special character, otherwise it is only an ordinary attack.
Naturally the diversion must at the same time always have an object of attack, for it is only the value of this object that will induce the enemy to send troops for its protection; besides, in case the undertaking does not succeed as a diversion, this object is a compensation for the forces expended in the attempt.
These objects of attack may be fortresses, or important magazines, or rich and large towns, especially capital cities, contributions of all kinds; lastly, assistance may be afforded in this way to discontented subjects of the enemy.
It is easy to conceive that diversions may be useful, but they certainly are not so always; on the contrary, they are just as often injurious. The chief condition is that they should withdraw from the principal theatre of the war more of the enemy’s troops than we employ on the diversion; for if they only succeed in drawing off just the same number, then their efficacy as diversions, properly called, ceases, and the undertaking becomes a mere subordinate attack. Even where, on account of circumstances, we have in view to attain a very great end with a very small force, as, for instance, to make an easy capture of an important fortress, and another attack is made adjoining to the principal attack, to assist the latter, that is no longer a diversion. When two states are at war, and a