For the use of an army of a hundred thousand men about to march forward against an enemy, all the parallel roads within a space of at least ten miles are needed, and the more of them there are the better, since the columns can thereby be made shorter, and the trains be sent by the interior roads. Where a sufficient number of parallel roads exist, available for the army, it is usual to put about a division on each—sometimes the whole of a corps—according to the nature of the country and the objects to be attained. We will attempt to illustrate the march of an army by columns in the following diagram.
Suppose that E and F are two towns thirty miles apart, and that there are road connections as represented in the diagram. The army represented by the dotted line A B, wishes to move to attack the army C D. Cavalry, followed by infantry columns, would be sent out on the roads E M N and E G I, the cavalry going off toward P and K to protect the flanks, and the infantry taking position at I and O. Meantime another column, behind which are the baggage trains, covered with a rear guard, has moved to L. If the three points I, L, and O are reached simultaneously, the army can safely establish its new line, the baggage trains are entirely protected, and the whole country is occupied as effectually as if every acre were in possession.
The formation of a marching column varies according to circumstances, but is usually somewhat as follows, when moving toward an enemy:
The dots representing the ambulances and wagon trains do not show the true proportion of these to the rest of the column, and it cannot be given except at too great a sacrifice of space. They occupy more road than all the other parts of the column combined. With the advance guard go the engineers and pioneers, to repair the roads, make bridges, etc.
The difficulties and dangers attending a flank march can be made apparent by a diagram:
Let A B and C D represent two armies drawn up against each other in three lines of battle, on opposite sides of a stream, E F. The commander of the army A B, finding he cannot cross and drive the enemy from their works, determines, by a flank march to the left, to go around them, crossing at the point E. In order to effect this he must send his trains off by the road I K L to some interior line, and then slowly unfold his masses upon the single road K E H. By the time the head of his column is at H the rear has not perhaps left K, and thus the whole length of his army is exposed on its side to an attack by the enemy, which may sever it into two unsupporting portions. It will be perceived that to accomplish such marches with security, they must be made in secret as far as possible, until a portion of the marching force reaches the rear of the enemy; the column must be kept compact, and great vigilance must be exercised. In his progress from the Rapidan to the James, General Grant made three movements of this character with entire success, each time putting our forces so far in the rear of the rebels that they were compelled to hasten their own retreat instead of delaying to avail themselves of the opportunity for attacking.
Besides the topography of the country, various circumstances influence the manner in which a march is conducted—particularly the position of the enemy. When following a retreating foe, the cavalry is sent in the advance, supported by some infantry and horse artillery, to harass the rear guard, and, if practicable, delay the retreat until the main army can come up. This was the case in the peninsula campaign, from Yorktown to the Chickahominy. Again, the exact position of the enemy may not be known, or he may have large bodies in different places, so that his intentions cannot be surmised. It is then necessary to scatter the army so as to cover a number of threatened points, care being exercised to have all the different bodies within supporting distances, and to be on guard against a sudden concentration of the enemy between them. This was the case in the campaign which ended so gloriously at Gettysburg. The rebels were then threatening both Harrisburg and Baltimore, and the two extremities of our army were over thirty miles apart, so as to be concentrated either on the right, left, or centre, as events might determine. It happened that a collision was brought on at Gettysburg, and both armies immediately concentrated there. The corps on the right of our army was obliged to march about thirty-two miles, performing the distance in about eighteen or nineteen hours, and arriving in time to participate in the second day's battle. As much skill is evinced by a commander in preliminary manœuvring marches and the assignment of positions to the different portions of his army as in the direction of a battle. Napoleon gained many of his victories through the effects of such manœuvres.
Time is a very important element in marching. An army which can march five miles a day more than its opponent will almost certainly be victorious, for it can go to his flank, or assail him when unprepared, Frederick the Great achieved his successes by imparting mobility to his troops, and Napoleon also was a master of that peculiar feature in that faculty of command of which we have before spoken, that enables a leader to obtain from his men the maximum amount of continued exertion. To achieve facility in marching, all the equipments of the soldiers should be as light as possible, and the columns should be encumbered with no more trains than are absolutely indispensable. Officers of the highest class must be prepared to forego unnecessary luxuries, and to march with nothing more than a blanket, a change of clothing, and rations for a few days in their haversacks.
When a march is contemplated, orders are issued from the general headquarters prescribing all the details—the time at which each corps is to start, the roads to be taken, the precautions to be observed, and the points to be gained. Usually an early hour in the morning is fixed for the commencement of the march. If not in the immediate presence of the enemy, and a surprise is not intended, the reveillé is beaten about three o'clock, and the sleepy soldiers arouse from their beds on the ground, pack up their tents, blankets, and equipments, get a hasty breakfast, and fall into their ranks. If some commander—perhaps of a regiment only—has been dilatory, the whole movement is delayed. Many well-formed plans have been defeated by the indolence of a subordinate commander and his failure to put his troops in motion at the designated hour. Such a delay may embarrass the whole army by detaining other portions, whose movements are to be governed by those of the belated fragment. At four o'clock, if orders have been obeyed, the long columns are moving. Perhaps four or five hours are occupied in filing out into the road. While the sun is rising and the birds engaged at their matins, the troops are trudging along at that pace of three miles an hour, which seems so tardy, but which, persisted in day after day, traverses so great a distance. Every hour there is ten or fifteen minutes' halt, enabling the rear to close up, and the men to relieve themselves temporarily of their guns and knapsacks. Soon the heat commences to grow oppressive, the dust rises in suffocating clouds, knapsacks weigh like lead, and the artillery horses pant as they drag the heavy guns. But the steady tramp must be continued till about eleven o'clock, when a general halt under the shelter of some cool woods, by the side of a stream, is ordered. Two or three hours of welcome rest are here employed in dinner and finishing the broken morning's nap. After the intenser heat of the day is past, the tramp recommences, and continues till six or seven o'clock, when the place appointed for encamping is reached. Soon white tents cover every hill and plain and valley, the weary animals are unharnessed, trees and fence rails disappear rapidly to feed the consuming camp fires, there is a universal buzz formed from the laugh, the song, the shout, and the talking of twenty thousand voices: it gradually subsides, the fires grow dim, and silence and darkness fall upon the scene.