In the second chapter of the second book, Strategy has been defined as “the employment of the battle as the means towards the attainment of the object of the War.” Properly speaking it has to do with nothing but the battle, but its theory must include in this consideration the instrument of this real activity—the armed force—in itself and in its principal relations, for the battle is fought by it, and shows its effects upon it in turn. It must be well acquainted with the battle itself as far as relates to its possible results, and those mental and moral powers which are the most important in the use of the same. Strategy is the employment of the battle to gain the end of the War; it must therefore give an aim to the whole military action, which must be in accordance with the object of the War; in other words, Strategy forms the plan of the War, and to this end it links together the series of acts which are to lead to the final decision, that, is to say, it makes the plans for the separate campaigns and regulates the combats to be fought in each. As these are all things which to a great extent can only be determined on conjectures some of which turn out incorrect, while a number of other arrangements pertaining to details cannot be made at all beforehand, it follows, as a matter of course, that Strategy must go with the Army to the field in order to arrange particulars on the spot, and to make the modifications in the general plan, which incessantly become necessary in War. Strategy can therefore never take its hand from the work for a moment. That this, however, has not always been the view taken is evident from the former custom of keeping Strategy in the cabinet and not with the Army, a thing only allowable if the cabinet is so near to the Army that it can be taken for the chief head-quarters of the Army. Theory will therefore attend on Strategy in the determination of its plans, or, as we may more properly say, it will throw a light on things in themselves, and on their relations to each other, and bring out prominently the little that there is of principle or rule. If we recall to mind from the first chapter how many things of the highest importance War touches upon, we may conceive that a consideration of all requires a rare grasp of mind.