According to our classification, therefore, tactics _is the theory of the use of military forces in combat_. Strategy _is the theory of the use of combats for the object of the War_. The way in which the conception of a single, or independent combat, is more closely determined, the conditions to which this unit is attached, we shall only be able to explain clearly when we consider the combat; we must content ourselves for the present with saying that in relation to space, therefore in combats taking place at the same time, the unit reaches just as far as _personal command_ reaches; but in regard to time, and therefore in relation to combats which follow each other in close succession, it reaches to the moment when the crisis which takes place in every combat is entirely passed. That doubtful cases may occur, cases, for instance, in which several combats may perhaps be regarded also as a single one, will not overthrow the ground of distinction we have adopted, for the same is the case with all grounds of distinction of real things which are differentiated by a gradually diminishing scale. There may, therefore, certainly be acts of activity in War which, without any alteration in the point of view, may just as well be counted strategic as tactical; for example, very extended positions resembling a chain of posts, the preparations for the passage of a river at several points, &c. Our classification reaches and covers only the _use of the military force_. But now there are in War a number of activities which are subservient to it, and still are quite different from it; sometimes closely allied, sometimes less near in their affinity. All these activities relate to the _maintenance of the military force_. In the same way as its creation and training precede its use, so its maintenance is always a necessary condition. But, strictly viewed, all activities thus connected with it are always to be regarded only as preparations for fighting; they are certainly nothing more than activities which are very close to the action, so that they run through the hostile act alternate in importance with the use of the forces. We have therefore a right to exclude them as well as the other preparatory activities from the Art of War in its restricted sense, from the conduct of War properly so called; and we are obliged to do so if we would comply with the first principle of all theory, the elimination of all heterogeneous elements. Who would include in the real “conduct of War” the whole litany of subsistence and administration, because it is admitted to stand in constant reciprocal action with the use of the troops, but is something essentially different from it?