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.
In like manner as to the staff. The more intimately it comes into contact with the troops, the more useful and valuable it becomes. The almost entire separation of the staff from the line, as now practised by us, and hitherto by the French, has proved mischievous, and the great retinues of staff-officers with which some of our earlier generals began the war were simply ridiculous. I don't believe in a chief of staff at all, and any general commanding an army, corps, or division, that has a staff-officer who professes to know more than his chief, is to be pitied. Each regiment should have a competent adjutant, quartermaster, and commissary, with two or three medical officers. Each brigade commander should have the same staff, with the addition of a couple of young aides-de-camp, habitually selected from the subalterns of the brigade, who should be good riders, and intelligent enough to give and explain the orders of their general.
The same staff will answer for a division. The general in command of a separate army, and of a corps d'armee, should have the same professional assistance, with two or more good engineers, and his adjutant-general should exercise all the functions usually ascribed to a chief of staff, viz., he should possess the ability to comprehend the scope of operations, and to make verbally and in writing all the orders and details necessary to carry into effect the views of his general, as well as to keep the returns and records of events for the information of the next higher authority, and for history. A bulky staff implies a division of responsibility, slowness of action, and indecision, whereas a small staff implies activity and concentration of purpose. The smallness of General Grant's staff throughout the civil war forms the best model for future imitation. So of tents, officers furniture, etc., etc. In real war these should all be diacarded, and an army is efficient for action and motion exactly in the inverse ratio of its impedimenta. Tents should be omitted altogether, save one to a regiment for an office, and a few for the division hospital. Officers should be content with a tent fly, improvising poles and shelter out of bushes. The tents d'abri, or shelter-tent, carried by the soldier himself, is allsufficient. Officers should never seek for houses, but share the condition of their men.