The practical importance of this conception will now become clear. It will be seen to afford the logical or theoretical exposition of what we began by stating in its purely concrete form. When a Chief of Staff is asked for a war plan he must not say we will make war in such and such a way because it was Napoleon's or Moltke's way. He will ask what is the political object of the war, what are the political conditions, and how much does the question at issue mean respectively to us and to our adversary. It is these considerations which determine the nature of the war. This primordial question settled, he will be in a position to say whether the war is of the same nature as those in which Napoleon's and Moltke's methods were successful, or whether it is of another nature in which those methods failed. He will then design and offer a
war plan, not because it has the hall-mark of this or that great master of war, but because it is one that has been proved to fit the kind of war in hand. To assume that one method of conducting war will suit all kinds of war is to fall a victim to abstract theory, and not to be a prophet of reality, as the narrowest disciples of the Napoleonic school are inclined to see themselves.
Hence, says Clausewitz, the first, the greatest and most critical decision upon which the Statesman and the General have to exercise their judgment is to determine the nature of the war, to be sure they do not mistake it for something nor seek to make of it something which from its inherent conditions it can never be. "This," he declares, "is the first and the most far-reaching of all strategical questions."
The first value, then, of his theory of war is that it gives a clear line on which we may proceed to determine the nature of a war in which we are about to engage, and to ensure that we do not try to apply to one nature of war any particular course of operations simply because they have proved successful in another nature of war. It is only, he insists, by regarding war not as an independent thing but as a political instrument that we can read aright the lessons of history and understand for our practical guidance how wars must differ in character according to the nature of the motives and circumstances from which they proceed. This conception, he claims, is the first ray of light to guide us to a true theory of war and thereby enable us to classify wars and distinguish them one from another.
Jomini, his great contemporary and rival, though proceeding by a less philosophical but no less lucid method, entirely endorses this view. A Swiss soldier of fortune, his
experience was much the same as that of Clausewitz. It was obtained mainly on the Staff of Marshal Ney and subsequently on the Russian headquarter Staff. He reached no definite theory of war, but his fundamental conclusions were the same. The first chapter of his final work, Précis de l'art de la Guerre, is devoted to "La Politique de la Guerre." In it he classifies wars into nine categories according to their political object, and he lays it down as a base proposition "That these
different kinds of war will have more or less influence on the nature of the operations which will be demanded to attain the end in view, on the amount of energy that must be put forth, and on the extent of the undertakings in which we must engage." "There will," he adds, "be a great difference in the operations according to the risks we have to run."
Both men, therefore, though on details of means they were often widely opposed, are agreed that the fundamental conception of war is political. Both of course agree that if we isolate in our mind the forces engaged in any theatre of war the abstract conception reappears. So far as those forces are concerned, war is a question of fighting in which each belligerent should endeavour by all means at his command and with all his energy to destroy the other. But even so they may find that certain means are barred to them for political reasons, and at any moment the fortune of war or a development of the political conditions with which it is entangled may throw them back upon the fundamental political theory.
That theory it will be unprofitable to labour further at this point. Let it suffice for the present to mark that it gives us a conception of war as an exertion of violence to secure a political end which we desire to attain, and that from this broad and simple formula we are able to deduce at once that wars will vary according to the nature of the end and the intensity of our desire to attain it. Here we may leave it to gather force and coherence as we examine the practical considerations which are its immediate outcome.