In the seventeenth and eighteenth centuries, when the improvements in the firearms of infantry occasioned a great increase of that arm, and allowed of its being deployed in such long thin lines, the order of battle was thereby simplified, but, at the same time it became more difficult and more artificial in the carrying out, and as no other way of disposing of cavalry at the commencement of a battle was known but that of posting them on the wings, where they were out of the fire and had room to move, therefore in the order of battle the army always became a closed inseparable whole. If such an army was divided in the middle, it was like an earthworm cut in two: the wings had still life and the power of motion, but they had lost their natural functions. The army lay, therefore, in a manner under a spell of unity, and whenever any parts of it had to be placed in a separate position, a small organisation and disorganisation became necessary. The marches which the whole army had to make were a condition in which, to a certain extent, it found itself out of rule. If the enemy was at hand, the march had to be arranged in the most artificial manner, and in order that one line or one wing might be always at the prescribed distance from the other, the troops had to scramble over everything: marches had also constantly to be stolen from the enemy, and this perpetual theft only escaped severe punishment through one circumstance, which was, that the enemy lay under the same ban. Hence, when, in the latter half of the eighteenth century, it was discovered that cavalry would serve just as well to protect a wing if it stood in rear of the army as if it were placed on the prolongation of the line, and that, besides this, it might be applied to other purposes than merely fighting a duel with the enemy’s cavalry, a great step in advance was made, because now the army in its principal extension or front, which is always the breadth of its order of battle (position), consisted entirely of homogeneous members, so that it could be formed of any number of parts at pleasure, each part like another and like the whole. In this way it ceased to be one single piece and became an articulated whole, consequently pliable and manageable: the parts might be separated from the whole and then joined on again without difficulty, the order of battle always remained the same.—Thus arose the corps consisting of all arms, that is, thus such an organisation became possible, for the want of it had been felt long before. That all this relates to the combat is very natural. The battle was formerly the whole war, and will always continue to be the principal part of it; but, the order of battle belongs generally more to tactics than strategy, and it is only introduced here to show how tactics in organising the whole into smaller wholes made preparations for strategy.