But these four conditions are only the chief points which relate to the subject; a number of local and special circumstances attach themselves to these, and often attain to an influence more decisive and important than that of the principal ones themselves. Selecting only the most essential, we mention the state of the roads, the nature of the country through which they pass, the means of cover which are afforded by rivers, mountains, and morasses, the seasons and weather, the importance of particular convoys, such as siege trains, the number of light troops, etc., etc.
On all these circumstances, therefore, will depend the effect with which a general can act on his opponent’s communications; and by comparing the result of the whole of these circumstances on the one side with the result of the whole on the other, we obtain a just estimate of the relative advantages of both systems of communication, on which will depend which of the two generals can play the highest game.
What here seems so prolix in the explanation is often decided in the concrete case at first sight; but still, the tact of a practised judgment is required for that, and person must have thought over every one of the cases now developed in order to see in its true light the absurdity of those critical writers who think they have settled something by the mere words “turning” and “acting on a flank,” without giving their reasons.
We now come to the second chief condition, under which the strategic action against the enemy’s flank may take place.
If the enemy is hindered from advancing by any other cause but the resistance which our army opposes, let that cause be what it may, then our army has no reason to be apprehensive about weakening itself by sending out detachments to harass the enemy; for if the enemy should