Marches are a mere passage from one position to another under two primary conditions.
The first is the due care of the troops, so that no forces shall be squandered uselessly when they might be usefully employed; the second, is precision in the movements, so that they may fit exactly. If we marched 100,000 men in one single column, that is, upon one road without intervals of time, the rear of the column would never arrive at the proposed destination on the same day with the head of the column; we must either advance at an unusually slow pace, or the mass would, like a thread of water, disperse itself in drops; and this dispersion, together with the excessive exertion laid upon those in rear owing to the length of the column, would soon throw everything into confusion.
If from this extreme we take the opposite direction, we find that the smaller the mass of troops in one column the greater the ease and precision with which the march can be performed. The result of this is the need of a division quite irrespective of that division of an army in separate parts which belongs to its position; therefore, although the division into columns of march originates in the strategic disposition in general, it does not do so in every particular case. A great mass which is to be concentrated at any one point must necessarily be divided for the march. But even if a disposition of the army in separate parts causes a march in separate divisions, sometimes the conditions of the primitive disposition, sometimes those of the march, are paramount. For instance, if the disposition of the troops is one made merely for rest, one in which a battle is not expected, then the conditions of the march predominate, and these conditions are chiefly the choice of good, well-frequented roads. Keeping in view this difference, we choose a road in the one case