For the rapid transmission of orders in an army covering a large space of ground, the magnetic telegraph is by far the best, though habitually the paper and pencil, with good mounted orderlies, answer every purpose. I have little faith in the signal-service by flags and torches, though we always used them; because, almost invariably when they were most needed, the view was cut off by intervening trees, or by mists and fogs. There was one notable instance in my experience, when the signal-flags carried a message. of vital importance over the heads of Hood's army, which had interposed between me and Allatoona, and had broken the telegraph-wires--as recorded in Chapter XIX.; but the value of the magnetic telegraph in war cannot be exaggerated, as was illustrated by the perfect concert of action between the armies in Virginia and Georgia during 1864. Hardly a day intervened when General Grant did not know the exact state of facts with me, more than fifteen hundred miles away as the wires ran. So on the field a thin insulated wire may be run on improvised stakes or from tree to tree for six or more miles in a couple of hours, and I have seen operators so skillful, that by cutting the wire they would receive a message with their tongues from a distant station. As a matter of course, the ordinary commercial wires along the railways form the usual telegraph-lines for an army, and these are easily repaired and extended as the army advances, but each army and wing should have a small party of skilled men to put up the field-wire, and take it down when done. This is far better than the signal-flags and torches. Our commercial telegraph-lines will always supply for war enough skillful operators.
The value of railways is also fully recognized in war quite as much as, if not more so than, in peace. The Atlanta campaign would simply have beep impossible without the use of the railroads from Louisville to Nashville-one hundred and eighty-five miles--from Nashville to Chattanooga-one hundred and fifty-one miles--and from Chattanooga to Atlanta-one hundred and thirty-seven miles. Every mile of this "single track" was so delicate, that one man could in a minute have broken or moved a rail, but our trains usually carried along the tools and means to repair such a break. We had, however, to maintain strong guards and garrisons at each important bridge or trestle--the destruction of which would have necessitated time for rebuilding. For the protection of a bridge, one or two log block houses, two stories high, with a piece of ordnance and a small infantry guard, usually sufficed. The block-house had a small parapet and ditch about it, and the roof was made shot proof by earth piled on. These points could usually be reached only by a dash of the enemy's cavalry, and many of these block houses successfully resisted serious attacks by both cavalry and artillery. The only block-house that was actually captured on the main was the one described near Allatoona. Our trains from Nashville forward were operated under military rules, and ran about ten miles an hour in gangs of four trains of ten cars each. Four such groups of trains daily made one hundred and sixty cars, of ten tons each, carrying sixteen hundred tons, which exceeded the absolute necessity of the army, and allowed for the accidents that were common and inevitable. But, as I have recorded, that single stem of railroad, four hundred and seventy-three miles long, supplied an army of one hundred thousand men and thirty-five thousand animals for the period of one hundred and ninety-six days, viz., from May 1 to November 12, 1864. To have delivered regularly that amount .of food and forage by ordinary wagons would have required thirty-six thousand eight hundred wagons of six mules each, allowing each wagon to have hauled two tons twenty miles each day, a simple impossibility in roads such as then existed in that region of country. Therefore, I reiterate that the Atlanta campaign was an impossibility without these railroads; and only then, because we had the men and means to maintain and defend them, in addition to what were necessary to overcome the enemy. Habitually, a passenger-car will carry fifty men with their necessary baggage. Box-cars, and even platform-cars, answer the purpose well enough, but they, should always have rough board-seats. For sick and wounded men, box-cars filled with straw or bushes were usually employed. Personally, I saw but little of the practical working of the railroads, for I only turned back once as far as Resaca; but I had daily reports from the engineer in charge, and officers who came from the rear often explained to me the whole thing, with a description of the wrecked trains all the way from Nashville to Atlanta. I am convinced that the risk to life to the engineers and men on that railroad fully equaled that on the skirmish-line, called for as high an order of courage, and fully equaled it in importance. Still, I doubt if there be any necessity in time of peace to organize a corps specially to work the military railroads in time of war, because in peace these same men gain all the necessary experience, possess all the daring and courage of soldiers, and only need the occasional protection and assistance of the necessary train-guard, which may be composed of the furloughed men coming and going, or of details made from the local garrisons to the rear.
For the transfer of large armies by rail, from one theatre of action to another by the rear--the cases of the transfer of the Eleventh and Twelfth Corps-General Hooker, twenty-three thousand men--from the East to Chattanooga, eleven hundred and ninety-two miles in seven days, in the fall of 1863; and that of the Army of the Ohio--General Schofield, fifteen thousand men--from the valley of the Tennessee to Washington, fourteen hundred miles in eleven days, en route to North Carolina in January, 1865, are the best examples of which I have any knowledge, and reference to these is made in the report of the Secretary of War, Mr. Stanton, dated November 22, 1865.
Engineer troops attached to an army are habitually employed in supervising the construction of forts or field works of a nature more permanent than the lines need by the troops in motion, and in repairing roads and making bridges. I had several regiments of this kind that were most useful, but as a rule we used the infantry, or employed parties of freedmen, who worked on the trenches at night while the soldiers slept, and these in turn rested by day. Habitually the repair of the railroad and its bridges was committed to hired laborers, like the English navvies, under the supervision of Colonel W. W. Wright, a railroad-engineer, who was in the military service at the time, and his successful labors were frequently referred tc in the official reports of the campaign.
For the passage of rivers, each army corps had a pontoon-train with a detachment of engineers, and, on reaching a river, the leading infantry division was charged with the labor of putting it down. Generally the single pontoon-train could provide for nine hundred feet of bridge, which sufficed; but when the rivers were very wide two such trains would be brought together, or the single train was supplemented by a trestle-bridge, or bridges made on crib-work, out of timber found near the place. The pontoons in general use were skeleton frames, made with a hinge, so as to fold back and constitute a wagon-body. In this same wagon were carried the cotton canvas cover, the anchor and chains, and a due proportion of the balks, cheeses, and lashings. All the troops became very familiar with their mechanism and use, and we were rarely delayed by reason of a river, however broad. I saw, recently, in Aldershot, England, a very complete pontoon-train; the boats were sheathed with wood and felt, made very light; but I think these were more liable to chafing and damage in rough handling than were our less expensive and rougher boats. On the whole, I would prefer the skeleton frame and canvas cover to any style of pontoon that I have ever seen.
In relation to guards, pickets, and vedettes, I doubt if any discoveries or improvements were made during our war, or in any of the modern wars in Europe. These precautions vary with the nature of the country and the situation of each army. When advancing or retreating in line of battle, the usual skirmish-line constitutes the picket-line, and may have "reserves," but usually the main line of battle constitutes the reserve; and in this connection I will state that the recent innovation introduced into the new infantry tactics by General Upton is admirable, for by it each regiment, brigade, and division deployed, sends forward as "skirmishers" the one man of each set of fours, to cover its own front, and these can be recalled or reenforced at pleasure by the bugle-signal.
For flank-guards and rear-guards, one or more companies should be detached under their own officers, instead of making up the guard by detailing men from the several companies.
For regimental or camp guards, the details should be made according to existing army regulations; and all the guards should be posted early in the evening, so as to afford each sentinel or vedette a chance to study his ground before it becomes too dark.