If, then, there is anywhere a necessity for drawing a line between two different activities, it is here; and in order to see clearly the importance of this idea, we need only just to call to mind how often eminent personal fitness in one field has turned out nothing but the most useless pedantry in the other. It is also in no way difficult to separate in idea the one activity from the other, if we look at the combatant forces fully armed and equipped as a given means, the profitable use of which requires nothing more than a knowledge of their general results. The Art of War is therefore, in its proper sense, the art of making use of the given means in fighting, and we cannot give it a better name than the “_Conduct of War_.” On the other hand, in a wider sense all activities which have their existence on account of War, therefore the whole creation of troops, that is levying them, arming, equipping, and exercising them, belong to the Art of War. To make a sound theory it is most essential to separate these two activities, for it is easy to see that if every act of War is to begin with the preparation of military forces, and to presuppose forces so organised as a primary condition for conducting War, that theory will only be applicable in the few cases to which the force available happens to be exactly suited. If, on the other hand, we wish to have a theory which shall suit most cases, and will not be wholly useless in any case, it must be founded on those means which are in most general use, and in respect to these only on the actual results springing from them. The conduct of War is, therefore, the formation and conduct of the fighting. If this fighting was a single act, there would be no necessity for any further subdivision, but the fight is composed of a greater or less number of single acts, complete in themselves, which we call combats, as we have shown in the first chapter of the first book, and which form new units. From this arises the totally different activities, that of the _formation_ and _conduct_ of these single combats in themselves, and the _combination_ of them with one another, with a view to the ultimate object of the War. The first is called _tactics_, the other _strategy_. This division into tactics and strategy is now in almost general use, and every one knows tolerably well under which head to place any single fact, without knowing very distinctly the grounds on which the classification is founded. But when such divisions are blindly adhered to in practice, they must have some deep root. We have searched for this root, and we might say that it is just the usage of the majority which has brought us to it. On the other hand, we look upon the arbitrary, unnatural definitions of these conceptions sought to be established by some writers as not in accordance with the general usage of the terms.