third falls upon one of them, such an event is very commonly called a diversion—but such an attack differs in nothing from an ordinary attack except in its direction; there is, therefore, no occasion to give it a particular name, for in theory it should be a rule only to denote by particular names such things as are in their nature distinct.
But if small forces are to attract large ones, there must obviously be some special cause, and, therefore, for the object of a diversion it is not sufficient merely to detach some troops to a point not hitherto occupied.
If the assailant with a small corps of 1000 men overruns one of his enemy’s provinces, not belonging to the theatre of war, and levies contribution, etc., it is easy to see beforehand that the enemy cannot put a stop to this by detaching 1000 men, but that if he means to protect the province from invaders, he must at all events send a considerably larger force. But it may be asked cannot a defender, instead of protecting his own province, restore the balance by sending a similar detachment to plunder a province in our country? Therefore, if an advantage is to be obtained by an aggressor in this way, it must first be ascertained that there is more to be got or to be threatened in the defender’s provinces than in his own. If this is the case, then no doubt a weak diversion will occupy a force on the enemy’s side greater than that composing the enterprise. On the other hand, this advantage naturally diminishes as the masses increase, for 50,000 men can defend a province of moderate extent not only against equal but even against somewhat superior numbers. The advantage of large diversions is, therefore, very doubtful, and the greater they become the more decisive must be the other circumstances which favour a diversion if any good is to come out of such an enterprise upon the whole.
Now these favourable circumstances may be:—
a. Forces which the assailant holds available for a diversion without weakening the great mass of his force.