Report of Maj. Gen. George B. McClellan, U. S. Army,
commanding the Army of the Potomac (Part 1)

No. 1. -- Extract, embracing the "First Period," from Maj. Gen. George B. McClellan's report of the operations of the Army of the Potomac from July 27, 1861, to November 9, 1862.
O.R.-- SERIES I--VOLUME 5 [S# 5]

CHAPTER I.

NEW YORK, August 4, 1863.

        SIR: I have the honor to submit herein the official report of the operations of the Army of the Potomac while under my charge. Accompanying it are the reports of the corps, division, and subordinate commanders pertaining to the various engagements, battles, and occurrences of the campaigns, and important documents connected with its organization, supply, and movements. These, with lists of maps and memoranda submitted, will be found appended, duly arranged, and marked for convenient reference.
        Charged in the spring of 1861 with the operations in the Department of the Ohio, which included the States of Illinois, Indiana, Ohio, and latterly Western Virginia, it had become my duty to counteract the hostile designs of the enemy in Western Virginia, which were immediately directed to the destruction of the Baltimore and Ohio Railroad and the possession of the Kanawha Valley, with the ultimate object of gaining Wheeling and the control of the Ohio River.
        The successful affairs of Philippi, Rich Mountain, Carrick's Ford, &c., had been fought, and I had acquired possession of all Western Virginia north of the Kanawha Valley, as well as of the lower portion of that valley.
        I had determined to proceed to the relief of the Upper Kanawha Valley as soon as provision was made for the permanent defense of the mountain passes leading from the east into the region under our control, when I received at Beverly, in Randolph County, on the 21st of July, 1861, intelligence of the unfortunate result of the battle of Manassas, fought on that day. On the 22d I received an order by telegraph directing me to turn over command to Brigadier-General Rosecrans and repair at once to Washington. I had already caused reconnaissances to be made for intrenchments at the Cheat Mountain Pass, also on the Huntersville road, near Elkwater, and at Red House, near the main road from Romney to Grafton. During the afternoon and night of the 22d I gave the final instructions for the construction of these works, turned over the command to Brigadier-General Rosecrans, and started on the morning of the 23d for Washington, arriving there on the afternoon of the 26th. On the 27th I assumed command of the Division of the Potomac, comprising the troops in and around Washington, on both banks of the river.
        With this brief statement of the events which immediately preceded my being called to the command of the troops at Washington I proceed to an account, from such authentic data as are at hand, of my military operations while commander of the Army of the Potomac.
        The subjects to be considered naturally arrange themselves as follows: The organization of the Army of the Potomac; the military events connected with the defenses of Washington from July, 1861, to March, 1862; the campaign on the Peninsula, and that in Maryland.
        The great resources and capacity for powerful resistance of the South at the breaking out of the rebellion, and the full proportions of the great conflict about to take place, were sought to be carefully measured, and I had also endeavored by every means in my power to impress upon the authorities the necessity for such immediate and full preparation as alone would enable the Government to prosecute the war on a scale commensurate with the resistance to be offered.
        On the 4th of August, 1861, I addressed to the President the following memorandum, prepared at his request:

MEMORANDUM.

        The object of the present war differs from those in which nations are usually engaged mainly in this, that the purpose of ordinary war is to conquer a peace and make a treaty on advantageous terms. In this contest it has become necessary to crush a population sufficiently numerous, intelligent, and warlike to constitute a nation, We have not only to defeat their armed and organized forces in the field, but to display such an overwhelming strength as will convince all our antagonists, especially those of the governing, aristocratic class, of the utter impossibility of resistance. Our late reverses make thin course imperative. Had we been successful in the recent battle (Manassas), it is possible that we might have been spared the labor and expenses of a great effort.
        Now we have no alternative. Their success will enable the political leaders of the rebels to convince the mass of their people that we are inferior to them in force and courage, and to command all their resources The contest began with a class; now it is with a people. Our military success can alone restore the former issue.
        By thoroughly defeating their armies, taking their strong places, and pursuing a rigidly protective policy as to private property and unarmed persons, and a lenient course as to private soldiers, we may well hope for a permanent restoration of a peaceful Union. But in the first instance the authority of the Government must be supported by overwhelming physical force.
        Our foreign relations and financial credit also imperatively demand that the military action of the Government should be prompt and irresistible.
        The rebels have chosen Virginia as their battle-field, and it seems proper, for us to make the first great struggle there. But, while thus directing our main efforts, it is necessary to diminish the resistance there offered us by movements on other points both by land and water.
        Without entering at present into details, I would advise that a strong movement be made on the Mississippi, and that the rebels be driven out of Missouri.
        As soon as it becomes perfectly clear that Kentucky is cordially united with us, I would advise a movement through that State into Eastern Tennessee, for the purpose of assisting the Union men of that region and of seizing the railroads leading from Memphis to the East. The possession of those roads by us, in connection with the movement on the Mississippi, would go far towards determining the evacuation of Virginia by the rebels. In the mean time all the passes into Western Virginia from the East should be securely guarded, but I would advise no movement from that quarter towards Richmond, unless the political condition of Kentucky renders it impossible or inexpedient for us to make the movement upon Eastern Tennessee through that State. Every effort should, however, be made to organize, equip, and arm as many troops as possible in Western Virginia, in order to render the Ohio and Indiana regiments available for other operations.
        At as early a day as practicable it would be well to protect and reopen the Baltimore and Ohio Railroad. Baltimore and Fort Monroe should be occupied by garrisons sufficient to retain them in our possession.
        The importance of Harper's Ferry and the line of the Potomac in the direction of Leesburg will be very materially diminished so soon as our force in this vicinity becomes organized, strong, and efficient, because no capable general will cross the river north of this city when we have a strong army here ready to cut off his retreat.
        To revert to the West: It is probable that no very large additions to the troops now in Missouri will be necessary to secure that State.
        I presume that the force required for the movement down the Mississippi will be determined by its commander and the President. If Kentucky assumes the right position, not more than 20,000 will be needed, together with those that can be raised in that State and Eastern Tennessee, to secure the latter region and its railroads, as well as ultimately to occupy Nashville.
        The Western Virginia troops, with not more than 5,000 to 10,000 from Ohio and Indiana, should, under proper management, suffice for its protection.
        When we have reorganized our main army here 10,000 men ought to be enough to protect the Baltimore and Ohio Railroad and the Potomac; 5,000 will garrison Baltimore, 3,000 Fort Monroe, and not more than 20,000 will be necessary at the utmost for the defense of Washington.
        For the main army of operations I urge the following composition:

  Men
250 regiments of infantry, say 225,000
100 field batteries, 600 guns 15000
28 regiments of cavalry 25,500
5 regiments engineer troops 7,500
Total 273,000

        The force must be supplied with the necessary engineer and pontoon trains, and with transportation for everything save tents. Its general line of operations should be so directed that water transportation can be availed of from point to point by means of the ocean and the rivers emptying into it. An essential feature of the plan of operations will be the employment of a strong naval force, to protect the movement of a fleet of transports intended to convey a considerable body of troops from point to point of the enemy's sea-coast, thus either creating diversions and rendering it necessary for them to detach largely from their main body in order to protect such of their cities as may be threatened, or else landing and forming establishments on their coast at any favorable places that opportunity might offer. This naval force should also cooperate with the main army in its efforts to seize the important seaboard towns of the rebels.
        It cannot be ignored that the construction of railroads has introduced a new and very important element into war, by the great facilities thus given for concentrating at particular positions large masses of troops from remote sections, and by creating few strategic points and lines of operations.
        It is intended to overcome this difficulty by the partial operations suggested, and such others as She particular case may require. We must endeavor to seize places on the railways in the rear of the enemy's points of concentration, and we must threaten their seaboard cities, in order that each State may be forced, by the necessity of its own defense, to diminish its contingent to the Confederate army.
        The proposed movement down the Mississippi will produce important results in this connection. That advance and the progress of the main army at the East will materially assist each other by diminishing the resistance to be encountered by each.
        The tendency of the Mississippi movement upon all questions connected with cotton is too well understood by the President and Cabinet to need any illustration from me.
        There is another independent movement that has often been suggested, and which has always recommended itself to my judgment. I refer to a movement from Kansas and Nebraska through the Indian Territory upon Red River and Western Texas, for the purpose of protecting and developing the latent Union and free-State sentiment well known to predominate in Western Texas, and which, like a similar sentiment in Western Virginia, will, if protected, ultimately organize that section into a free State. How far it will be possible to support this movement by an advance through New Mexico from California is a matter which I have not sufficiently examined to be able to express a decided opinion. If at all practicable it is eminently desirable, as bringing into play the resources and warlike qualities of the Pacific States, as well as identifying them with our cause and cementing the bond of union between them and the General Government.
        If it is not departing too far from my province, I will venture to suggest the policy of an intimate alliance and cordial understanding with Mexico; their sympathies and interests are with us--their antipathies exclusively against our enemies and their institutions. I think it would not be difficult to obtain from the Mexican Government the right to use, at least during the present contest, the road from Guaymas to New Mexico. This concession would very materially reduce the obstacles of the column moving from the Pacific. A similar permission to use their territory for the passage of troops between the Panuco and the Rio Grande would enable us to throw a column of troops by a good road from Tampico, or some of the small harbors north of it, upon and across the Rio Grande, without risk, and scarcely firing a shot.
        To what extent, if any, it would be desirable to take into service and employ Mexican soldiers is a question entirely political, on which I do not venture to offer an opinion.
        The force I have recommended is large; the expense is great. It is possible that a smaller force might accomplish the object in view, but I understand it to be the purpose of this great nation to re-establish the power of its Government and restore peace to its citizens in the shortest possible time.
        The question to be decided is simply this: Shall we crush the rebellion at one blow, terminate the war in one campaign, or shall we leave it as a legacy for our descendants?
        When the extent of the possible line of operations is considered, the force asked for for the main army under my command cannot be regarded as unduly large; every mile we advance carries us farther from our base of operations and renders detachments necessary to cover our communications, while the enemy will be constantly concentrating as he falls back. I propose, with the force which I have requested, not only to drive the enemy out of Virginia and occupy Richmond, but to occupy Charleston, Savannah, Montgomery, Pensacola, Mobile, and New Orleans; in other words, to move into the heart of the enemy's country and crush the rebellion in its very heart.
        By seizing and repairing the railroads as we advance the difficulties of transportation will be materially diminished. It is, perhaps, unnecessary to state that, in addition to the forces named in this memorandum, strong reserves should be formed, ready to supply any losses that may occur.
        In conclusion, I would submit that the exigencies of the Treasury may be lessened by making only partial payments to our troops when in the enemy's country, and by giving the obligations of the United States for such sup lies as may there be obtained.

GEO. B. McCLELLAN,
Major-General.

        I do not think the events of the war have proved these views upon the method and plans of its conduct altogether incorrect. They certainly have not proved my estimate of the number of troops and scope of operations too large. It is probable that I did underestimate the time necessary for the completion of arms and equipments. It was not strange, however, that by many civilians intrusted with authority there should have been an exactly opposite opinion held on both these particulars.
        The result of the first battle of Manassas had been almost to destroy the morale and organization of our Army, and to alarm Government and people. The national capital was in danger; it was necessary, besides holding the enemy in check, to build works for its defense strong and capable of being held by a small force.
        It was necessary also to create a new army for active operations, and to expedite its organization, equipment, and the accumulation of the material of war, and to this not inconsiderable labor all my energies for the next three months were constantly devoted.
        Time is a necessary element in the creation of armies, and I do not therefore think it necessary to more than mention the impatience with which many regarded the delay in the arrival of new levies, though recruited and pressed forward with unexampled rapidity, the manufacture and supply of arms and equipments, or the vehemence with which an immediate advance upon the enemy's works directly in our front was urged by a patriotic but sanguine people.
        The President, too, was anxious for the speedy employment of our Army, and, although possessed of my plans through frequent conferences, desired a paper from me upon the condition of the forces under my command and the immediate measures to be taken to increase their efficiency. Accordingly, in the latter part of October I addressed the following letter to the Secretary of War:

Hon. SIMON CAMERON,
Secretary
of War.

        SIR: In conformity with a personal understanding with the President yesterday, I have the honor to submit the following statement of the condition of the army under my command, and the measures required for the preservation of the Government and the suppression of the rebellion:
        It will be remembered that in a memorial I had the honor to address to the President soon after my arrival in Washington, and in my communication addressed to Lieutenant-General Scott under date of 8th of August, in my letter to the President authorizing him, at his request, to withdraw the letter written by me to General Scott, and in my letter of the 8th of September, answering your note of inquiry of that date, my views on the same subject are frankly and fully expressed.
        In these several communications I have stated the force I regarded as necessary to enable this army to advance with a reasonable certainty of success, at the same time leaving the capital and the line of the Potomac sufficiently guarded not only to secure the retreat of the main army in the event of disaster, but to render it out of the enemy's power to attempt a diversion in Maryland.
        So much time has passed and the winter is approaching so rapidly, that but two courses are left to the Government, viz, either to go into winter quarters or to assume the offensive with forces greatly inferior in numbers to the army I regarded as desirable and necessary. If political considerations render the first course unadvisable, the second alone remains. While I regret that it has not been deemed expedient or perhaps possible, to concentrate the forces of the nation in this vicinity (remaining on the defensive elsewhere), keeping the attention and efforts of the Government fixed upon this as the vital point where the issue of the great contest is to be decided, it may still be that, by introducing unity of action and design among the various armies of the land, by determining the courses to be pursued by the various commanders under one general plan, transferring from the other armies the superfluous strength not required for the purpose in view, and thus re-enforcing this main army, whose destiny it is to decide the controversy, we may yet be able to move with a reasonable prospect of success before the winter is fairly upon us.
        The nation feels, and I share that feeling, that the Army of the Potomac holds the fate of the country in its hands. The stake is so vast, the issue so momentous, and the effect of the next battle will be so important throughout the future as well as the present, that I continue to urge, as I have ever done since I entered upon the command of this armor, upon the Government to devote its energies and its available resources towards increasing the numbers and efficiency of the army on which its salvation depends. A statement, carefully prepared by the chiefs of engineers and artillery of this army, gives as the necessary garrison of this city and its fortifications 33,795 men, say 35,000. The present garrison of Baltimore and its dependencies is about 10,000. I have sent the chief of my staff to make a careful examination into the condition of these troops, and to obtain the information requisite to enable me to decide whether this number can be diminished or the reverse.
        At least 5,000 men will be required to watch the river hence to Harper's Ferry and its vicinity; probably 8,000 to guard the Lower Potomac. As you are aware, all the information we have from spies, prisoners, &c., agrees in showing that the enemy have a force on the Potomac not less than 150,000 strong, well drilled and equipped, ably commanded, and strongly intrenched. It is plain, therefore, that to insure success, or to render it reasonably certain, the active army should not number less than 150,000 efficient troops, with 400 guns, unless some material change occurs in the force in front of us. The requisite force for an advance movement by the Army of the Potomac may be thus estimated:

  Men Guns
Column of active operations 150,000 400
Garrison of the city of Washington 35,000 40
To guard the Potomac to Harper's Ferry 5,000 12
To guard the Lower Potomac 8,000 24
Garrison for Baltimore and Annapolis 10,000 12
Total effective force required 208,000 488

or an aggregate, present and absent, of about 240,000 men, should the losses by sickness, &c., not rise to a higher percentage than at present.
        Having stated what I regard as the requisite force to enable this army to advance, I now proceed to give the actual strength of the Army of the Potomac. The aggregate strength of the Army of the Potomac, by the official report on the morning of the 27th instant, was 168,318 officers and men of all grades and arms. This includes the troops at Baltimore and Annapolis, on the Upper and Lower Potomac, the sick, absent, &c. The force present for duty was 147,695. Of this number 4,268 cavalry were completely unarmed, 3,163 cavalry only partially armed, 5,979 infantry unequipped, making 13,410 unfit for the field (irrespective of those not yet sufficiently drilled), and reducing the effective force to 134,285, and the number disposable for an advance to 76,285. The infantry regiments are, to a considerable extent, armed with unserviceable weapons. Quite a large number of good arms, which had been intended for this army, were ordered elsewhere, leaving the Army of the Potomac insufficiently and, in some cases, badly armed. On the 30th of September there were with this army '228 field guns ready for the field. So far as arms and equipments are concerned, some of the batteries are still quite raw, and unfit to go into action. I have intelligence that eight New York batteries are en route hither; two others are ready for the field. I will still (if the New York batteries have six guns each) be 112 guns short of the number required for the active column, saying nothing for the present of those necessary for the garrisons and corps on the Potomac, which would make a total deficiency of 200 guns.
        I have thus briefly stated our present condition and wants It remains to suggest the means of supplying the deficiencies:
        First. That all the cavalry and infantry arms, as fast as procured, whether manufactured in this country or purchased abroad, be sent to this army until it is fully prepared for the field.
        Second. That the two companies of the Fourth Artillery, now understood to be en route from Fort Randall to Fort Monroe, be ordered to this army, to be mounted at once; also that the companies of the Third Artillery, en route from California, be sent here. Had not the order for Smead's battery to come here from Harrisburg to replace the battery I gave General Sherman been so often countermanded, I would again ask for it.
        Third. That a more effective regulation may he made authorizing the transfer of men from the volunteers to the regular batteries, infantry and cavalry, that we may make the best possible use of the invaluable regular "skeletons."
        Fourth. I have no official information as to the United States forces elsewhere, but from the best information I can obtain from the War Department and other sources I am led to believe that the United States troops are:

In Western Virginia, about 30,000
In Kentucky 40,000
In Missouri 80,000
In Fortress Monroe 11,000
Total 161,000

        Besides these, I am informed that more than 100,000 are in progress of organization in other Northern and Western States.
        I would, therefore, recommend that, not interfering with Kentucky, there should be retained in Western Virginia and Missouri a sufficient force for defensive purposes, and that the surplus troops be sent to the Army of the Potomac, to enable it to assume the offensive; that the same course be pursued in respect to Fortress Monroe, and that no further outside expeditions be attempted until we have fought the great battle in front of us.
        Fifth. That every nerve be strained to hasten the enrollment, organization, and armament of new batteries and regiments of infantry.
        Sixth. That all the battalions now raised for new regiments of regular infantry be at once ordered to this army, and that the old infantry and cavalry en route from California be ordered to this army immediately on their arrival in New York.
        I have thus indicated in a general manner the objects to be accomplished and the means by which we may gain our ends. A vigorous employment of these means will, in my opinion, enable the Army of the Potomac to assume successfully this season the offensive operations which, ever since entering upon the command, it has been my anxious desire and diligent effort to prepare for and prosecute. The advance should not be postponed beyond the 25th of November, if possible to avoid it.
        Unity in councils,, the utmost vigor and energy in action, are indispensable. The entire military field should be grasped as a whole, and not in detached parts. One plan should be agreed upon and pursued; a single will should direct and carry out these plans.
        The great object to be accomplished, the crushing defeat of the rebel army (now) at Manassas, should never for one instant be lost sight of, but all the intellect and means and men of the Government poured upon that point. The loyal States possess ample force to effect all this and more. The rebels have displayed energy, unanimity, and wisdom worthy of the most desperate days of the French revolution. Should we do less?
        The unity of this nation, the preservation of our institutions, are so dear to me, that I have willingly sacrificed my private happiness with the single object of doing my duty to my country. When the task is accomplished, I shall be glad to return to the obscurity from which events have drawn me. Whatever the determination of the Government may be, I will do the best I can with the Army of the Potomac, and will share its fate, whatever may be the task imposed upon me.
        Permit me to add that, on this occasion, as heretofore, it has been my aim neither to exaggerate nor underrate the power of the enemy, nor fail to express clearly the means by which, in my judgment, that power may be broken.
        Urging the energy of preparation and action, which has ever been my choice, but with the fixed purpose by no act of mine to expose the Government to hazard by premature movement, and requesting that this communication may be laid before the President, I have the honor to be, very respectfully, your obedient servant,

GEO. B. McCLELLAN,
Major-General.

        When I assumed command in Washington, on the 27th of July, 1861, the number of troops in and around the city was about 50,000 infantry, less than 1,000 cavalry, and 650 artillerymen, with nine imperfect field batteries, of thirty pieces. On the Virginia bank of the Potomac the brigade organization of General McDowell still existed, and the troops were stationed at and in rear of Fort Corcoran, Arlington, and Fort Albany, Fort Runyon, Roach's Mill, Cole's Mill, and in the vicinity of Fort Ellsworth, with a detachment at the Theological Seminary. There were no troops south of Hunting Creek, and many of the regiments were encamped on the low grounds bordering the Potomac, seldom in the best positions for defense, and entirely inadequate in numbers and condition to defend the long line from Fort Corcoran to Alexandria. On the Maryland side of the river, upon the heights overlooking the Chain Bridge, two regiments were stationed, whose commanders were independent of each other. There were no troops on the important Tennallytown road, or on the roads entering the city from the south. The camps were located without regard to purposes of defense or instruction, the roads were not picketed, and there was no attempt at an organization into brigades.
        In no quarter were the dispositions for defense such as to offer a vigorous resistance to a respectable body of the enemy, either in the position and numbers of the troops or the number and character of the defensive works. Earthworks, in the nature of tetes-de-pont, looked upon the approaches to the Georgetown Aqueduct and Ferry, the Long Bridge, and Alexandria, by the Little River turnpike, and some simple defensive arrangements were made at the Chain Bridge. With the latter exception not a single defensive work had been commenced on the Maryland side. There was nothing to prevent the enemy shelling the city from heights within easy range, which could be occupied by a hostile column almost without resistance. Many soldiers had deserted, and the streets of Washington were crowded with straggling officers and men, absent from their stations without authority, whose behavior indicated the general want of discipline and organization.
        I at once designated an efficient staff, afterwards adding to it as opportunity was afforded and necessity required, who zealously cooperated with me in the labor of bringing order out of confusion, reassigning troops and commands, projecting and throwing up defensive works, receiving and organizing, equipping and providing, for the new levies arriving the city.
        The valuable services of these officers in their various departments during this and throughout the subsequent periods of the history of the Army of the Potomac can hardly be sufficiently appreciated. Their names and duties will be given in another part of this report, and they are commended to the favorable notice of the War Department.
        The restoration of order in the city of Washington was effected through the appointment of a provost-marshal, whose authority was supported by the few regular troops within my command. These troops were thus in position to act as a reserve, to be sent to any point of attack where their services might be most wanted. The energy and ability displayed by Col. A. Porter, the provost-marshal, and his assistants, and the strict discharge of their duty by the troops, produced the best results, and Washington soon became one of the most quiet cities in the Union.
        The new levies of infantry, upon arriving in Washington, were formed into provisional brigades, and placed in camp in the suburbs of the city, for equipment, instruction, and discipline. As soon as regiments were in a fit condition for transfer to the forces across the Potomac they were assigned to the brigades serving there. Brig. Gen. F. J. Porter was at first assigned to the charge of the provisional brigades. Brig. Gen. A. E. Burnside was the next officer assigned to this duty, from which, however, he was soon relieved by Brig. Gen. S. Casey, who continued in charge of the newly-arriving regiments until the Army of the Potomac departed for the Peninsula, in March, 1862. The newly-arriving artillery troops reported to Brig. Gen. William F. Barry, the chief of artillery, and the cavalry to Brig. Gen. George Stoneman, the chief of cavalry.
        By the 15th of October the number of troops in and about Washington inclusive of the garrison of the city and Alexandria, the city guard, and the forces on the Maryland shore of the Potomac below Washington, and as far as Cumberland above, the troops under the command of General Dix at Baltimore and its dependencies, were as follows:

Total present for duty 133,201
Total sick 9,290
Total in confinement 1,156
Aggregate present 143,647
Aggregate absent 8,404
Grand aggregate 152,051

The following table exhibits similar data for the periods stated, including the troops in Maryland and Delaware:

Date  Present For duty  Sick  In Confinement  Total present and absent
December 1, 1861 169,452 15,102 2,189 198,213
January 1, 1862 191,480 14,790 2,260 219,707
February 1, 1862 190,806 14,363 2,917 222,196
March 1, 1862 193,142 13,167 2,108 221,987

For convenience of reference the strength of the Army of the Potomac at subsequent periods is given:

Date Officers Present for duty Men Present for duty Officers Sick Men Sick Officers in arrest or confinement Men in arrest or confinement Aggregate Absent by authority Absent without authority Grand Aggregate Present and Absent
April 30 4,725 104,610 233 5,385 41 356 115,356 11,037 --- 126,387
June 20 4,665 101,160 496 10,541 44 320 117,226 27,700 887 145,813
July 10 3,834 85,715 685 15,959 60 213 106,466 34,638 3,782 144,888

        In organizing the Army of the Potomac and preparing it for the field, the first step taken was to organize the infantry into brigades of four regiments each, retaining the newly-arrived regiments on the Maryland side until their armament and equipment were issued and they had obtained some little elementary instruction before assigning them per manently to brigades. When the organization of the brigades was well established and the troops somewhat disciplined and instructed, divisions of three brigades each were gradually formed, as is elsewhere stated in this report. Although I was always in favor of the organization into army corps as an abstract principle, I did not desire to form them until the army had been for some little time in the field, in order to enable the general officers first to acquire the requisite experience as division commanders on active service and that I might be able to decide from actual trial who were best fitted to exercise these important commands. For a similar reason I carefully abstained from making any recommendations for the promotion of officers to the grade of major-general.
        When new batteries of artillery arrived, they also were retained in Washington until their armament and equipment were completed and their instruction sufficiently advanced to justify their being assigned to divisions. The same course was pursued in regard to cavalry. I regret that circumstances have delayed the chief of cavalry, General George Stoneman, in furnishing his report upon the organization of that arm of service. It will, however, be forwarded as soon as completed, and will doubtless show that the difficult and important duties intrusted to him were efficiently performed. He encountered and overcame, as far as it was possible, continual and vexatious obstacles arising from the great deficiency of cavalry arms and equipments and the entire inefficiency of many of the regimental officers first appointed. This last difficulty was, to a considerable extent, overcome in the cavalry, as well as in the infantry and artillery, by the continual and prompt action of courts-martial and boards of examination. As rapidly as circumstances permitted every cavalry soldier was armed with a saber and revolver, and at least two squadrons in every regiment with carbines. It was intended to assign at least one regiment of cavalry to each division of the active army, besides forming a cavalry reserve of the regular regiments and some picked regiments of volunteer cavalry. Circumstances beyond my control rendered it impossible to carry out this intention fully, and the cavalry force serving with the army in the field was never as large as it ought to have been.
        It was determined to collect the regular infantry to form the nucleus of a reserve. The advantage of such a body of troops at a critical moment, especially in an army constituted mainly of new levies, imperfectly disciplined, has been frequently illustrated in military history, and was brought to the attention of the country at the first battle of Manassas. I have not been disappointed in the estimate formed of the value of these troops. I have always found them to be relied on. Whenever they have been brought under fire they have shown the utmost gallantry and tenacity. The regular infantry, which had been collected from distant posts and which had been recruited as rapidly as the slow progress of recruiting for the regular service Would allow, added to the small battalion with McDowell's army which I found at Washington on my arrival, amounted on the 30th of August to 1,040 men; on the 28th of February, 1862, to 2,682, and on the 30th of April, to 4,603. On the 17th of May, 1862, they were assigned to General Porter's corps for organization as a division, with the Fifth Regiment New York Volunteers, which joined May 4, and the Tenth New York Volunteers, which joined subsequently. They remained from the commencement under the command of Brig. Gen. George Sykes, major Third Infantry, U.S. Army.

ARTILLERY.

        The creation of an adequate artillery establishment for an army of so large proportions was a formidable undertaking, and had it not been that the country possessed in the regular service a body of accomplished and energetic artillery officers, the task would have been almost hopeless.
        The charge of organizing this most important arm was confided to Major (afterwards Brig. Gen.) William F. Barry, chief of artillery, whose industry and zeal achieved the best results. The report of General Barry is appended among the accompanying documents. By referring to it will be observed that the following principles were adopted as the basis of organization :

* * * * * * * * * *

        The zeal and services of Maj. A. S. Webb, assistant to General Barry,. entitle him to especial praise. At the close of the Peninsular campaign General Barry assumed the duties of chief of artillery of the defenses of Washington, and was relieved in his former position by Col. Henry J. Hunt, who had commanded the artillery reserve with marked skill, and brought to his duties as chief of artillery the highest qualifications. The services of this distinguished officer in reorganizing and refitting the batteries prior to and after the battle of Antietam, and his gallant and skillful conduct on that field, merit the highest encomium in my power to bestow. His assistant, Major Doull, deserves high credit for his services and gallantry throughout both campaigns.
        The designations of the different batteries of artillery, both regular and volunteer, follow within a few pages.
        The following distribution of regiments and batteries was made, as a preliminary organization of the forces at hand, shortly after my arrival in Washington. The infantry, artillery, and cavalry, as fast as collected and brought into primary organization, were assigned to brigades and divisions, as indicated in the subjoined statements:

Organization of the Division of the Potomac, August 4, 1861.

        Brigadier-General Hunter's brigade.--Twenty-third, Twenty-fifth, Thirty-fifth, and Thirty-seventh Regiments New York Volunteers.
        Brigadier-General Heintzelman's brigade.
--Fifth Regiment Maine Volunteers, Sixteenth, Twenty-sixth, and Twenty-seventh Regiments New York Volunteers, and Tidbali's battery (A), Second U.S. Artillery. Briq. Gen. W. T. Sherman's brigade.--Ninth and Fourteenth Regiments Massachusetts Volunteers De Kalb [Fort -first] Regiment New York Volunteers, Fourth Regiment Michigan Volunteers, Hamilton's battery (E), Third U.S. Artillery, and Company I, Second U.S. Cavalry.
        Brigadier-General Kearny's brigade.
--First, Second, and Third Regiments New Jersey Volunteers, Greene's battery (G), Second U.S. Artillery, and Company G, Second U.S. Cavalry.
        Brigadier-General Hooker's
brigade--First and Eleventh Regiments Massachusetts Volunteers, Second Regiment New Hampshire Volunteers, and Twenty-sixth Regiment Pennsylvania Volunteers.
        Colonel Keyes' brigade
.--Twenty-second, Twenty-fourth, and Thirtieth Regiments New York Volunteers, and Fourteenth Regiment New York State Militia [Eighty-fourth Volunteers].
        Brigadier-General Franklin's brigade.
--Fifteenth, Eighteenth, Thirty-first, and Thirty-Second Regiments New York Volunteers, Platt's battery (M), Second U.S. Artillery, and Company C [First], New York (Lincoln) Cavalry.
        Colonel Blenker's brigade.
--Eighth and Twenty-ninth Regiments New York Volunteers, Twenty-seventh Regiment Pennsylvania Volunteers, and Garibaldi Guard [Thirty-ninth], New York Volunteers.
        Colonel Richardson's brigade.
--Twelfth Regiment New York Volunteers and Second and Third Regiments Michigan Volunteers.
        Brigadier-General Stone's brigade.
--Thirty-fourth and Tammany [Forty-second] Regiments New York Volunteers, First Regiment Minnesota Volunteers, and Second Regiment New York State Militia [Eighty-second Volunteers].
        Col. William F. Smith's brigade
.--Second and Third Regiments Vermont Volunteers, Sixth Regiment Maine Volunteers, Thirty-third Regiment New York Volunteers, Company H, Second U.S. Cavalry, and Captain Mott's New York battery.
        Colonel Couch's brigade
.--Second Regiment Rhode Island Volunteers, Seventh and Tenth Regiments Massachusetts Volunteers, and Thirty-sixth Regiment New York Volunteers.
        The Second Regiment Maine, the Second Regiment Wisconsin, and the Thirteenth Regiment New York Volunteers, stationed at Fort Corcoran.
        The Twenty-first Regiment New York Volunteers, stationed at Fort Runyon.
        The Seventeenth Regiment New York Volunteers, stationed at Fort Ellsworth.

        By October the new levies had arrived in sufficient numbers, and the process of organization so far carried on that the construction of divisions had been effected.
        The following statement exhibits the composition of the Army, October 15, 1861:

Organization of the Army of the Potomac, October 15, 1861.

        1. Brig. Gen. George Stokeman's cavalry command.--Fifth U.S. Cavalry., Fourth Pennsylvania Cavalry, Oneida Cavalry (first company), Eleventh Pennsylvania Cavalry (Harlan's), and Barker's Illinois Cavalry (one company).
        2. Col. H. J. Hunt's artillery reserve.--Batteries L, A, and B, Second U.S. Artillery; Batteries K and F, Third U.S. Artillery; Battery K, Fourth U.S. Artillery; Battery H, First U.S. Artillery, and Battery A, Fifth U.S. Artillery.

3. CITY GUARD, BRIG. GEN. ANDREW PORTER.

        Cavalry.--Companies A and E, Fourth U.S. Cavalry.
        Artillery.
--Battery K, Fifth U.S. Artillery.
        Infantry
.--Second and Third battalions U.S. Infantry, Company- Eighth and Company -- First U.S. Infantry, and Sturges' rifles (Illinois Volunteers).

4. BANKS' DIVISION.

        Cavalry.--Four companies Third Regiment New York Cavalry (Van Alen's).
        Artillery.
--Best's battery (F), Fourth U.S. Artillery; detachment Ninth New York Artillery; Matthews' battery (F), First Pennsylvania Artillery; Tompkins' battery (A), First Rhode Island Artillery.
        lnfantry.
--Abercrombie's brigade: Twelfth Massachusetts, Twelfth and Sixteenth Indiana, and Thirtieth Pennsylvania Volunteers. Stiles' brigade: Third Wisconsin, Twenty-ninth Pennsylvania, and Thirteenth Massachusetts Volunteers, and Ninth New York State Militia [Eighty-third Volunteers]. Gordon's brigade: Second Massachusetts, Twenty-eighth and Nineteenth New York, Fifth Connecticut, Forty-sixth and Twenty-eighth Pennsylvania, and First Maryland Volunteers.

McDOWELL'S DIVISION.

        Cavalry.--Second New York Cavalry. (Harris' Light), Colonel Davies.
        Artillery.
--Battery M, Second, and Battery G, First, U.S. Artillery.
        Infantry.--Keyes' brigade: Fourteenth New York State Militia [Eighty-fourth Volunteers], and Twenty-second, Twenty-fourth, and Thirtieth New York Volunteers. Wadsworth's brigade: Twelfth, Twenty-first, Twenty-third, and Thirty-fifth New York Volunteers. King's brigade: Second, Sixth, and Seventh Wisconsin, and Nineteenth Indiana Volunteers.

HEINTZELMAN'S DIVISION.

        Cavalry.--First New Jersey Cavalry, Colonel Halsted.
        Artillery.
--Thompson's battery (G), U.S. Artillery.
        Infantry.
--Richardson's brigade: Second, Third, and Fifth Michigan, and Thirty-seventh New York Volunteers. Sedgwick's brigade: Third and Fourth Maine and Thirty-eighth and Fortieth New York Volunteers. Jameson's brigade: Thirty-second, Sixty-third, Sixty-first, and Forty-fifth Pennsylvania Volunteers, and Wild Cat Reserves (Pennsylvania Volunteers).

F. J. PORTER'S DIVISION.

        Calvary.--Third Pennsylvania Cavalry, Colonel Averell, and Eighth Pennsylvania Cavalry, Colonel Gregg.
        Artillery.
--Battery E, Second, and Battery E, Third, U.S. Artillery. Infantry.--Morell's brigade: Thirty-third Pennsylvania, Fourth Michigan, Ninth Massachusetts, and Fourth New York Volunteers. Martindale's brigade: Thirteenth New York, Second Maine, and Eighteenth Massachusetts Volunteers, and De Kalb [Forty-first] Regiment New York Volunteers. Butterfield's brigade: Fiftieth New York, Eighty-third Pennsylvania, Seventeenth and Twenty-fifth New York Volunteers, and Stockton's Independent Michigan [Sixteenth] Regiment.

FRANKLIN'S DIVISION.

        Cavalry.--First New York Cavalry, Colonel McReynolds.
        Artillery.
--Batteries D and G, Second U.S. Artillery, and Hexamer's battery (New Jersey Volunteers).
        Infantry.
--Kearny's brigade: First, Second, Third, and Fourth New Jersey Volunteers. Slocum s brigade: Sixteenth, Twenty-sixth, and Twenty-seventh New York, and Fifth Maine Volunteers. Newton's brigade: Fifteenth, Eighteenth, Thirty-first, and Thirty-second New York Volunteers.

STONE'S DIVISION.

        Cavalry.--Six companies Third New York (Van Alen) Cavalry.
        Artillery.
--Kirby's battery (I), First United States; Vaughn's battery (B), First Rhode Island Artillery, and Bunting's Sixth New York Independent Battery.
        lnfantry.
--Gorman's brigade: Second New York State Militia [Eighty-second Volunteers], First Minnesota, Fifteenth Massachusetts, and Thirty-fourth New York Volunteers, and Tammany [Forty-second] Regiment New York Volunteers. Lander's brigade: Nineteenth and Twentieth Massachusetts, and Seventh Michigan Volunteers, and a company of Massachusetts Sharpshooters. Baker's brigade: Pennsylvania Volunteers (First, Second, and Third California).

BUELL'S DIVISION.

        Artillery.--Batteries D and H, First Pennsylvania Artillery.
        Infantry.
--Couch's brigade: Second Rhode Island, Seventh and Tenth Massachusetts, and Thirty-sixth New York Volunteers. Graham's brigade: Twenty-third and Thirty-first Pennsylvania, and Sixty-seventh (First Long Island) and Sixty-fifth (First U.S. Chasseurs) New York Volunteers. Peck's brigade: Thirteenth and Twenty-first Pennsylvania and Sixty-second (Anderson Zouaves) and Fifty-fifth New York Volunteers.

McCALL'S DIVISION.

        Cavalry.--First Pennsylvania Reserve Cavalry, Colonel Bayard.
        Artillery.
--Easton's battery (A), Cooper's battery (B), and Kerns' battery (G), First Pennsylvania Artillery.
        Infantry.
--Meade's brigade: First Rifles, Pennsylvania Reserves, Fourth, Third, Seventh, Eleventh, and Second Pennsylvania Reserve Infantry. ----- brigade: Fifth, First, and Eighth Pennsylvania Reserve Infantry. ------- brigade: Tenth, Sixth, Ninth, and Twelfth Pennsylvania Reserve Infantry.

HOOKER'S DIVISION.

        Cavalry.--Eight companies Third Indiana Cavalry, Lieutenant-Colonel Carter.
        Artillery.
--Elder's battery (E), First U.S. Artillery.
        Infantry.
---- brigade: First and Eleventh Massachusetts, Second New Hampshire, Twenty-sixth Pennsylvania, and First Michigan Volunteers. Sickles' brigade: First, Second, Third, Fourth, and Fifth Regiments Excelsior Brigade [Seventieth, Seventy-first, Seventy-second, Seventy-third, and Seventy-fourth], New York Volunteers.

BLENKER'S BRIGADE.

        Cavalry.--Fourth New York Cavalry (mounted rifles), Colonel Dickel.
        Artillery
.--One battery.
        Infantry.
--Eighth and Twenty-ninth New York, Twenty-seventh and Thirty-fifth Pennsylvania Volunteers, Garibaldi Guard, and Cameron Rifles ([Thirty-ninth and Sixty-eighth] New York Volunteers).

SMITH'S DIVISION.

        Cavalry.--Fifth Pennsylvania Cavalry (Cameron Dragoons), Colonel Friedman.
        Artillery.
--Ayres' battery (F), Fifth U.S. Artillery; Mott's Second New York Independent battery, and Barr's battery (E), First Pennsylvania Artillery.
        Infantry.
-- brigade: Second, Third, Fourth, and Fifth Vermont Volunteers.
        Stevens' brigade: Thirty-third and Forty-ninth New York and Sixth Maine Volunteers, and Seventy-ninth New York State Militia [Seventy-ninth Volunteers]. Hancock's brigade: Forty-seventh and Forty-ninth Pennsylvania, Forty-third New York, and Fifth Wisconsin Volunteers. Companies B and E, Berdan Sharpshooters.
        Casey's Provisional Brigades.
--Fifth, Sixth, and Seventh New Jersey Volunteers, Roundhead Regiment ( [One hundredth] Pennsylvania Volunteers), Battalion District of Columbia Volunteers, Fortieth Pennsylvania, Eighth New Jersey, and Fourth New Hampshire Volunteers.

5. GARRISONS.

        Alexandria.--Brigadier-General Montgomery, military governor. Cameron Guard ([Eighty-eighth] Pennsylvania Volunteers).
        Fort Albany.
--Fourteenth Massachusetts Volunteers.
        Fort Richardson
.--Fourth Connecticut Volunteers.
        Fort Washington.
--Company D, First U.S. Artillery; Companies H and I, Thirty-seventh New York Volunteers, and United States recruits unassigned.

6. DIX'S DIVISION, BALTIMORE.

        Cavalry.--Company of Pennsylvania cavalry.
        Artillery.
--Battery I, Second U.S. Artillery, Second Massachusetts Light Battery, and a battery of New York artillery.
        Infantry.
--Third, Fourth, and Fifth New York, Seventeenth and Twenty-fifth Massachusetts, Twenty-first Indiana, Sixth Michigan, Fourth Wisconsin, Seventh Maine, Second Maryland Battalion, and Reading City Guard, volunteers.
        [Battery E, Third U.S. Artillery, the Seventy-ninth New York State Militia, the Forty-seventh Pennsylvania Volunteers, and the Roundhead Regiment were transferred to General Sherman's expedition.]

        On the 8th of March, 1862, the President directed, by the following order, the organization of the active portion of the Army of the Potomac into four army corps, and the formation of a fifth corps from the divisions of Banks and Shields. The following is the text of the President's order:

PRESIDENT'S GENERAL WAR ORDER, No. 2

EXECUTIVE MANSION,
Washington, March 8, 1862.

        Ordered, 1. That the major-general commanding the Army of the Potomac proceed forthwith to organize that part of the said army destined to enter upon active operations (including the reserve, but excluding the troops to be left in the fortifications about Washington) into four army corps, to be commanded according to seniority of rank, as follows:
        First Corps to consist of four divisions, and to be commanded by Maj. Gen. I. McDowell.
        Second Corps to consist of three divisions, and to be commanded by Brig. Gen. E. V. Sumner.
        Third Corps to consist of three divisions, and to be commanded by Brig. Gen. S. P. Heintzelman.
        Fourth Corps to consist of three divisions, and to be commanded by Brig. Gen. E. D. Keyes.
        2. That the divisions now commanded by the officers above assigned to the commands of army corps shall be embraced in and form part of their respective corps.
        3. The forces left for the defense of Washington will be placed in command of Brig. Gen. James S. Wadsworth, who shall also be military governor of the District of Columbia.
        4. That this order be executed with such promptness and dispatch as not to delay the commencement of the operations already directed to be undertaken by the Army of the Potomac.
        5. A fifth army corps, to be commanded by Maj. Gen. N. P. Banks, will be formed from his own and General Shields' (late General Lander's) divisions.

ABRAHAM LINCOLN.

        The following order, which was made as soon as circumstances permitted, exhibits the steps taken to carry out the requirements of the President's War Order, No. 2:

GENERAL ORDERS, No. 101

HEADQUARTERS ARMY OF THE POTOMAC,
Fairfax Court-House, Va., March 13, 1862.

        In compliance with the President's War Order, No. 2, of March 8, 1862, the active portion of the Army of the Potomac is formed into army corps, as follows:
        First Corps, Maj. Gen. Irvin McDowell, to consist for the present of the divisions of Franklin, McCall, and King.
        Second Corps, Brig. Gen. E.V. Sumner; divisions, Richardson, Blenker, and Sedgwick.
        Third Corps, Brig. Gen. S. P. Heintzelman; divisions, F. J. Porter, Hooker, and Hamilton.
        Fourth Corps, Brig. Gen. E. D. Keyes; divisions, Couch, Smith, and Casey.
        Fifth Corps, Maj. Gen. N. P. Banks; divisions, Williams and Shields.
        The cavalry regiments attached to divisions will for the present remain so. Subsequent orders will provide for these regiments, as well as for the reserve artillery, regular infantry, and regular cavalry. Arrangements will be made to unite the divisions of each army corps as promptly as possible.
        The commanders of divisions will at once report in person, or, where that is impossible, by letter to the commander of their army corps.

By command of Major-General McClellan:
A. V. COLBURN,

Assistant Adjutant-General.

        I add a statement of the organization and composition of the troops on April 1, commencing with the portion of the Army of the Potomac which went to the Peninsula, giving afterwards the regiments and batteries left on the Potomac and in Maryland and Virginia after April 1, 1862:

Troops of the Army of the Potomac sent to the Peninsula in March and early in April, 1862.

        1st. Cavalry reserve, Brig. Gen. P. St. G. Cooke.--Emory's brigade: Fifth U.S. Cavalry; Sixth U.S. Cavalry; Sixth Pennsylvania Cavalry. Blake's brigade: First U.S. Cavalry; Eighth Pennsylvania Cavalry; Barker's squadron Illinois cavalry.
        2d. Artillery reserve, Col. Henry J. Hunt: Graham's battery (K and G), First U. S., six Napoleon guns; Randol's battery (E), First U. S., six Napoleon guns; Carlisle's battery (E), Second U.S., six 20-pounder Parrott guns; Robertson's battery, Second U.S., six 3-inch ordnance guns; Benson's battery (M), Second U.S., six 3-inch ordnance guns; Tidball's battery (A), Second U.S., six 3-inch ordnance guns; Edwards' battery (L and M), Third U.S., six 10-pounder Parrott guns; Gibson's battery (C and G), Third U.S., six 3-inch ordnance guns; Livingston's battery (F and K), Third U.S., four 10-pounder Parrott guns; Howe's battery (G), Fourth U.S., six Napoleon guns; De Russy's battery (K), Fourth U.S., six Napoleon guns; Weed's battery (I), Fifth U.S., six 3-inch ordnance guns; Smead's battery (K), Fifth U. S, four Napoleon guns; Ames' battery (A), Fifth U.S., six (four 10-pounder Parrott and two Napoleon) guns; Diedrich's battery (A), New York artillery battalion, six 20-pounder Parrott guns; Voegelie's battery (B), New York artillery battalion, four 20-pounder Parrott guns; Knieriem's battery (C), New York artillery battalion, four 20-pounder Parrott guns; Grim's battery (D), New York artillery battalion, six 32-pounder howitzer guns; total, 100 guns.
        3d. Volunteer engineer troops, General Woodbury: Fifteenth New York Volunteers, Fiftieth New York Volunteers. Regular engineer troops, Captain Duane: Companies A, B, and C, U.S. Engineers. Artillery troops, with siege trains: First Connecticut Heavy Artillery, Colonel Tyler.
        4th. Infantry reserve (regular brigade), General Sykes: Nine companies Second U. S. Infantry, seven companies Third U.S. Infantry, ten companies Fourth U.S. Infantry, ten companies Sixth U.S. Infantry, eight companies Tenth and Seventeenth U.S. Infantry, six companies Eleventh U.S. Infantry, eight companies Twelfth U. S. Infantry, nine companies Fourteenth U.S. Infantry, and Fifth New York Volunteers, Colonel Warren.

SECOND CORPS, GENERAL SUMNER.

        Cavalry.--Eighth Illinois Cavalry, Colonel Farnsworth, and one squadron Sixth New York Cavalry.

RICHARDSON'S DIVISION.

        Artillery.--Clarke's battery (A and C), Fourth U.S., six Napoleon guns; Frank's battery (G), First New York, six 10-pounder Parrott guns; Pettit's battery (B), First New York, six 10-pounder Parrott guns; Hogan's battery (A), Second New York, six 10-pounder Parrott guns.
        Infantry.
--Howard's brigade: Fifth New Hampshire, Eighty-first Pennsylvania, and Sixty-first and Sixty-fourth New York Volunteers. Meagher's brigade: Sixty-ninth, Sixty-third, and Eighty-eighth New York Volunteers. French's brigade: Fifty-second, Fifty-seventh, and Sixty-sixth New York and Fifty-third Pennsylvania Volunteers.

SEDGWICK'S DIVISION.

        Artillery.--Kirby's battery (I), First U.S., six Napoleon guns; Tompkins' battery (A), First Rhode Island, six (four 10-pounder Parrott and two 12-pounder howitzer) guns; Bartlett's battery (B), First Rhode Island, six (four 10-pounder Parrott and two 12-pounder howitzer), guns; Owen's battery (G), six 3-inch ordnance guns.
        Infantry.
--Gorman s brigade: Second Now York State Militia, Fifteenth Massachusetts, Thirty-fourth New York, and First Minnesota Volunteers. Burns' brigade: Sixty-ninth, Seventy-first, Seventy-second, and One hundred and sixth Pennsylvania Volunteers. Dana's brigade: Nineteenth and Twentieth Massachusetts, Seventh Michigan, and Forty-second New York Volunteers.
        Note
.--Blenker's division detached, and assigned to the Mountain Department.

THIRD CORPS, GENERAL HEINTZELMAN

        Cavalry.--Third Pennsylvania Cavalry, Colonel Averell.

PORTER'S DIVISION.

        Artillery.--Griffin's battery (D), Fifth U.S., six 10-pounder Parrott guns; Weed-en's battery (c), Rhode Island; Martin's battery (c), Massachusetts, six Napoleon guns; Allen's battery (E), Massachusetts, six 3-inch ordnance guns.
        Infantry.
--Martindale's brigade: Second Maine, Eighteenth and Twenty-second Massachusetts, and Twenty-fifth and Thirteenth New York Volunteers. Morell's brigade: Fourteenth New York, Fourth Michigan, Ninth Massachusetts, and Sixty-sec-ond Pennsylvania Volunteers. Butterfield's brigade: Seventeenth, Forty-fourth, and Twelfth New York, Eighty-third Pennsylvania, and Stockton's [Sixteenth] Michigan Volunteers.
        First Berdan Sharpshooters.

HOOKER'S DIVISION,

        Artillery.--Hall's battery (H), First U.S., six (four 10-pounder Parrott and two 12-pounder howitzer) guns; Smith's battery, Fourth New York, six 10-pounder Parrott guns; Bramhall's battery, Sixth New York, six 3-inch ordnance guns; Osborn's battery (D), First New York Artillery, four 3-inch ordnance guns.
        Infantry
.--Sickles' brigade: First, Second, Third, Fourth, and Fifth Excelsior, New York. Naglee's brigade: First and Eleventh Massachusetts, Twenty-sixth Pennsylvania, and Second New Hampshire Volunteers. Colonel Starr's brigade: Fifth, Sixth, Seventh, and Eighth New Jersey Volunteers.

HAMILTON'S DIVISION.

        Artillery.--Thompson's battery (G), Second U.S., six Napoleon guns; Beam's battery (B), New Jersey, six (four 10-pounder Parrott and two Napoleon) guns; Randolph's battery (E), Rhode Island, six (four 10-pounder Parrott and two Napoleon) guns.
        Infantry.
--Jameson's brigade: One hundred and fifth, Sixty-third, and Fifty-seventh Pennsylvania and Eighty-seventh New York Volunteers. Birney's brigade: Thirty-eighth and Fortieth New York and Third and Fourth Maine Volunteers brigade: Second, Third, and Fifth Michigan and Thirty-seventh New York Volunteers.

FOURTH CORPS, GENERAL KEYES.

COUCH'S DIVISION.

        Artillery.--McCarthy's battery (C), First Pennsylvania, four 10-pounder Parrott guns; Flood's battery (D), First Pennsylvania, four 10-pounder Parrott guns; Miller's battery (E), First Pennsylvania, four Napoleon guns; Brady's battery (F), First Pennsylvania, four 10-pounder Parrott guns.
        Infantry.
--Graham's brigade: Sixty-seventh (First Long Island) and Sixty-fifth (First U.S. Chasseurs) New York, and Twenty-third, Thirty-first, and Sixty-first Pennsylvania Volunteers. Peck's brigade: Ninety-eighth, One hundred and second, and Ninety-third Pennsylvania, and Sixty-second and Fifty-fifth New York Volunteers. -------- brigade: Second Rhode Island, Seventh and Tenth Massachusetts, and Thirty-sixth New York Volunteers.

SMITH'S DIVISION.

        Artillery.--Ayres' battery (F), Fifth U.S., six (four 10-pounder Parrott and two Napoleon) guns; Mott's battery, Third New York, six (four 10-pounder Parrott and two Napoleon) guns; Wheeler's battery (E), First New York, four 3-inch ordnance guns; Kennedy's battery, First New York, six 3-inch ordnance guns.
        Infantry.
--Hancock's brigade: Fifth Wisconsin, Forty-ninth Pennsylvania, forty-third New York, and Sixth Maine Volunteers. Brooks' brigade: Second, Third, Fourth, Fifth, and Sixth Vermont Volunteers. Davidson's brigade: Thirty-third, Seventy-seventh, and Forty-ninth New York and Seventh Maine Volunteers.

CASEY'S DIVISION.

        Artillery.--Regan's battery, Seventh New York, six 3-inch ordnance guns: Fitch's battery, Eighth New York, six 3-inch ordnance guns; Bates' battery (A), First New York, six Napoleon guns; Spratt's battery (H), First New York, four 3-inch ordnance guns.
        Infantry.
--Keim's brigade: Eighty-fifth, One hundred and first, and One hundred and third Pennsylvania and Ninety-sixth New York Volunteers. Palmer's brigade: Eighty-fifth, Ninety-eighth, Ninety-second, Eighty-first, and Ninety-third New York Volunteers. -- brigade: One hundred and fourth and Fifty-second Pennsylvania, Fifty-sixth and One hundredth New York, and Eleventh Maine Volunteers.
        5th. Provost guard: Second U.S. Cavalry; battalions Eighth and Seventeenth U.S. Infantry.
        At general headquarters: Two companies Fourth U.S. cavalry, one company Onedia cavalry (New York volunteers), and one company Sturges' rifles (Illinois volunteers).

        The following troops of the Army of the Potomac were left behind or detached on and in front of the Potomac for the defense of that line April 1, 1862. Franklin's and McCall's divisions, at subsequent and different dates, joined the active portion of the army on the Peninsula. Two brigades of Shields' division joined at Harrison's Landing:

FIRST CORPS, GENERAL McDOWELL.

        Cavalry.--First, Second, and Fourth New York, and First Pennsylvania. Sharpshooters.--Second Regiment Berdan Sharpshooters.

FRANKLIN'S DIVISION.

        Artillery.--Platt's battery (D), Second U.S., six Napoleon guns; Porter's battery (A), Massachusetts, six (four 10-pounder Parrott and two 12-pounder howitzer) guns; Hexamer's battery (A), New Jersey, six (four 10-pounder Parrott and two 12-pounder howitzer) guns; Wilson's battery (F), First New York Artillery, four 3-inch ordnance guns.
        Infantry.
--Kearny's brigade: First, Second, Third, and Fourth New Jersey Volunteers. Slocum's brigade: Sixteenth and Twenty-seventh New York, Fifth Maine, and Ninety-sixth Pennsylvania Volunteers. Newton's brigade: Eighteenth, Thirty-first, and Thirty-second New York, and Ninety-fifth Pennsylvania Volunteers.

M'CALL'S DIVISION.

        Artillery.--Seymour's battery (C), Fifth U.S., six Napoleon guns; Easton's battery (A), First Pennsylvania, four Napoleon guns; Coopers battery (B), First Pennsylvania, six 10-pounder Parrott guns; Kerns' battery (G), First Pennsylvania, six (two 10-pounder and four 12-pounder) Parrott guns.
        Infantry.
--Reynolds' brigade: First, Second, Fifth, and Eighth Pennsylvania Reserve Regiments. Meade's brigade: Third, Fourth, Seventh, and Eleventh Pennsylvania Reserve Regiments. Ord's brigade: Sixth, Ninth, Tenth, and Twelfth Pennsylvania Reserve Regiments. First Pennsylvania Reserve Rifles.

KING'S DIVISION.

        Artillery.--Gibbon's battery (B), Fourth U.S., six Napoleon guns; Monroe's battery (D), First Rhode Island, six 10-pounder Parrott guns; Gerrish's battery CA), New Hampshire, six Napoleon guns; Durell's battery, Pennsylvania, six 10-pounder Parrott guns.
        Infantry.
--brigade: Second, Sixth, and Seventh Wisconsin, and Nineteenth Indiana Volunteers. Patrick's brigade: Twentieth, Twenty-first, Twenty-Third, and Twenty-fifth New York State Militia. Augur's brigade: Fourteenth New York State Militia [Eighty-fourth Volunteers], and Twenty-second, Twenty-fourth, and Thirtieth New York Volunteers.

FIFTH CORPS, GENERAL BANKS.

        Cavalry.--First Maine, First Vermont, First Michigan, First Rhode Island, Fifth and Eighth New York, Keys' battalion of Pennsylvania, eighteen companies of Maryland, one squadron of Virginia.
        Unattached.
--Twenty- eighth Pennsylvania Volunteers and Fourth Regiment Potomac Home Brigade (Maryland Volunteers).

WILLIAMS' DIVISION.

        Artillery.--Best's battery (F), Fourth U.S., six Napoleon guns; Hampton's battery, Maryland, four 10-pounder Parrott guns; Thompson's battery, Maryland, four 10-pounder Parrott guns; Matthews' battery (F), Pennsylvania, six 3-inch ordnance guns; Cothran's battery (M), First New York, six 10-pounder Parrott guns; Knap's battery, Pennsylvania, six 10-pounder Parrott guns ; McMahon's battery; New York, six 3-inch ordnance guns.
        Infantry.
--Abercrombie's brigade: Twelfth and Second Massachusetts, and Sixteenth Indiana, First Potomac Home Brigade (Maryland). one company Zouaves d'Afrique (Pennsylvania) Volunteers. ------- brigade: Ninth New York State Militia, [Eighty-third Volunteers], and Twenty-ninth Pennsylvania, Twenty-seventh Indiana, and Third Wisconsin Volunteers. ------- brigade: Twenty-eighth New York, Fifth Connecticut, Forty-sixth Pennsylvania, First Maryland, Twelfth Indiana, and Thirteenth Massachusetts Volunteers.

SHIELDS' DIVISION.

        Artillery.--Clark's battery (E), Fourth U.S., six 10-pounder Parrott guns; Jenks' battery (A), First Virginia, four 10-pounder Parrott and two 6-pounder guns; Davey's battery (B), First Virginia, two 10-pounder Parrott guns; Huntington s battery (A), First Ohio, six 13-pounder James guns; Robinson's battery (L), First Ohio, two 12-pounder howitzers and four 6-pounder guns, and -------- battery, Fourth Ohio Artillery.
        Infantry.
-------- -- brigade: Fourteenth Indiana, Fourth, Eighth, and Sixty-seventh Ohio Seventh Virginia, and Eighty-fourth Pennsylvania Volunteers. -------- brigade: Fifth, Sixty-second, and Sixty-sixth Ohio, Thirteenth Indiana, and Thirty-ninth Illinois Volunteers. ------- brigade: Seventh and Twenty-ninth Ohio, Seventh Indiana, First Virginia, and One hundred and tenth Pennsylvania Volunteers. Andrew S.S.

GENERAL WADSWORTH'S COMMAND.

        Cavalry.--First New Jersey Cavalry at Alexandria, and Fourth Pennsylvania Cavalry east of the Capitol.
        Artillery and Infantry.
--Tenth New Jersey Volunteers, Bladensburg road; One hundred and fourth New York Volunteers, Kalorama Heights; First Wisconsin Heavy Artillery, Fort Cass, Virginia; three batteries of New York artillery, Forts Ethan Allen and Marcy; depot of New York Light Artillery, Camp Barry; Second District of Columbia Volunteers, Washington City; Twenty-sixth Pennsylvania Volunteers, G-street wharf; Twenty-sixth New York Volunteers, Fort Lyon; Ninety-fifth New York Volunteers, Camp Thomas; Ninety-fourth New York and detachment of Eighty eighth Pennsylvania Volunteers Alexandria; Ninety-first Pennsylvania Volunteers, Franklin Square Barracks; Fourth New York Artillery, Forts Carroll and Greble; One hundred and twelfth Pennsylvania Volunteers, Fort Saratoga; Seventy-sixth New York Volunteers, Fort Massachusetts; Fifty-ninth New York Volunteers, Fort Pennsylvania; detachment of Eighty-eighth Pennsylvania Volunteers, Fort Good Hope ; Ninety-ninth Pennsylvania Volunteers, Fort Mahon; Second New York Light Artillery, Forts Ward, Worth, and Blenker; One hundred and seventh and Fifty-fourth Pennsylvania Volunteers, Kendall Green; Dickenson's Light Artillery, Eighty-sixth New York, and detachment of Eighty-eighth Pennsylvania Volunteers, east of the Capitol; Fourteenth Massachusetts (Volunteers) Heavy Artillery and Fifty-sixth Pennsylvania Volunteers, Forts Albany, Tillinghast, Richardson, Runyon, Jackson, Barnard, Craig, and Scott; detachments of Fourth U.S. Artillery and Thirty-seventh New York Volunteers, Fort Washington; Ninety-seventh, One hundred and first, and Ninety-first New York, and Twelfth Virginia Volunteers, Fort Corcoran.
        In camp near Washington.
--Sixth and Tenth New York, Swain's New York, and Second Pennsylvania Cavalry, all dismounted.
        These troops (3,359 men) were ordered to report to Colonel Miles, commanding the railroad guard, to relieve 3,306 older troops ordered to be sent to Manassas to report to General Abercrombie.

GENERAL DIX'S COMMAND, BALTIMORE.

        Cavalry.--First Maryland Cavalry and detachment of Purnell Legion Cavalry.
        Artillery.
--Battery I, Second U.S.; battery --, Maryland; battery L, First New York, and two independent batteries of Pennsylvania artillery.
        Infantry.
--Third, and Fourth New York, Eleventh, Eighty-seventh, and One hundred and eleventh Pennsylvania, detachment Twenty-first Massachusetts, Second Delaware, Second Maryland, First and Second Eastern Shore (Maryland) Home Guards, and Purnell Legion (two battalions) Maryland Volunteers.

        In a staff charged with labors so various and important as that of the Army of the Potomac, a chief was indispensable to supervise the various departments and to relieve the commanding general of details. The office of chief of staff, well known in European armies, had not been considered necessary in our small peace establishment. The functions of the office were not defined, and so far as exercised had been included in the Adjutant-General's Department. The small number of officers in this department, and the necessity for their employment in other duties, have obliged commanding generals during this war to resort to other branches of the service to furnish suitable chiefs of staff.
        On the 4th of September, 1861, I appointed Col. R. B. Marcy, of the Inspector-General's Department, chief of staff, and he entered upon service immediately, discharging the various and important duties with great fidelity, industry, and ability from this period until I was removed from command at Rectortown. Many improvements have been made during the war in our system of staff administration, but much remains to be done.
        Our own experience and that of other armies agree in determining the necessity for an efficient and able staff. To obtain this, our staff establishment should be based on correct principles, and extended to be adequate to the necessities of the service, and should include a system of staff and line education.
        The affairs of the Adjutant-General's Department, while I commanded the Army of the Potomac, were conducted by Brig. Gen. S. Williams, assisted by Lieut. Col. James A. Hardie, aide-de-camp. Their management of the department during the organization of the Army in the fall and winter of 1861 and during its subsequent operations in the field, was excellent. They were during the entire period assisted by Capt. Richard B. Irwin,-camp, and during the organization of the Army by the following-named officers: Capts. Joseph Kirkland, Arthur McClellan, M. T. McMahon, William P. Mason, and William F. Biddle, aides-de-camp.
        My personal staff, when we embarked for the Peninsula, consisted of Col. Thomas M. Key, additional aide-de-camp; Col. E. H. Wright, additional aide-de-camp and major Sixth U.S. Cavalry; Col. T. T. Gantt, additional aide-de-camp; Col. J. J. Astor, jr., volunteer aide-de-camp; Lieut. Col. A. V. Colburn, additional aide-de-camp, and captain Adju-tant-General's Department; Lieut. Col. N. B. Sweitzer, additional aide-de-camp, and captain First U.S. Cavalry; Lieut. Col. Edward McK. Hudson, additional aide-de camp, and captain Fourteenth U.S. Infantry; Lieut. Col. Paul Von Radowitz, additional aide-de-camp; Maj. H. von Hammerstein, additional aide-de-camp; Maj. W. W. Russell, U.S. Marine Corps: Maj. F. LeCompte, of the Swiss Army, volunteer aide-de-camp; Capts. George A. Custer, Joseph Kirkland, Arthur McClellan, L. P. D'Orleans, R. D'Orleans, M. T. McMahon. William P. Mason, jr., William F. Biddle, and E. A. Raymond, additional aides-de-camp.
        To this number I am tempted to add the Prince de Joinville, who constantly accompanied me through the trying campaign of the Peninsula, and frequently rendered important services. Of these officers Captain McMahon was assigned to the personal staff of Brigadier-General Franklin, and Captains Kirkland and Mason to that of Brig. Gen. F. J. Porter during the siege of Yorktown. They remained subsequently with those general officers. Major LeCompte left the Army during the siege of Yorktown; Colonels Gantt and Astor, Maj. Russell, Capts. L. P. D Orleans, R. D Orleans, and Raymond, at the close of the Peninsular campaign. Before its termination Capts. W. S. Abert and Charles R. Lowell, of the Sixth U.S. Cavalry, joined my staff as aides-de-camp, and remained with me until I was relieved from the command of the Army of the Potomac. All of these officers served me with great gallantry and devotion; they were ever ready to execute any service, no matter how dangerous, difficult, or fatiguing.

INSPECTOR-GENERAL'S DEPARTMENT.

        The highly important duties of this department were performed by Col. D. B. Sucker and Maj. N.H. Davis to my entire satisfaction. They introduced many valuable changes in the system of inspections and in the forms of reports, and so systematized the labors of the inspectors of corps and divisions that excellent results were obtained. The intelligent and energetic performance of their duties by these officers enabled me to keep myself well informed of the condition of the troops and to correct evils promptly.

ENGINEERS.

        When I assumed command of the Army of the Potomac I found Maj. J. G. Barnard, U.S. Engineers, subsequently brigadier-general of volunteers, occupying the position of chief engineer of that army. I continued him in the same office, and at once gave the necessary instructions for the completion of the defenses of the capital, and for the entire reorganization of the department. Under his direction the entire system of defenses was carried into execution. This was completed before the army departed for Fort Monroe, and is a sufficient evidence of the skill of the engineers and the diligent labor of the troops.
        For some months after the organization of the Army of the Potomac was commenced there were no engineer troops with it. At length, however, three companies were assigned. Under the skillful management of Capt. J. C. Duane, U.S. Engineers, these new companies rapidly became efficient, and, as will be seen, rendered most valuable service during the ensuing campaigns.
        The number of engineer troops being entirely inadequate to the necessities of the army, an effort was made to partially remedy this defect by detailing the Fifteenth and Fiftieth New York Volunteers, which contained many sailors and mechanics, as engineer troops. They were first placed under the immediate superintendence of Lieut. Col. B. S. Alexander, U.S. Engineers, by whom they were instructed in the duties of pontoniers, and became somewhat familiar with those of sappers and miners. Previous to the movement of the army for the Peninsula this brigade was placed under the command of Brig. Gen. D. P. Woodbury, major U.S. Engineers.
        The labor of preparing the engineer and bridge trains devolved chiefly upon Captain Duane, who was instructed to procure the new model French bridge train, as I was satisfied that the India-rubber pontoon was entirely useless for the general purposes of a campaign.
        The engineer department presented the following complete organization when the army moved for the Peninsula:
        Brig. Gen. J. G. Barnard, chief engineer; First Lieut. H. L. Abbot, Topographical Engineers, aide-de-camp. Brigade volunteer engineers, Brigadier-General Woodbury commanding; Fifteenth New York Volunteers, Col. J. McLeod Murphy ; Fiftieth New York Volunteers, Col. C. B. Stuart. Battalion three companies U.S. Engineers, Capt. J. C. Duane commanding; companies respectively commanded by First Lieuts. C. B. Reese, C. E. Cross, and O. E. Babcock, U. S. Engineers. The chief engineer was ably assisted in his duties by Lieut. Col. B. S. Alexander, and First Lieuts. C. B. Comstock, M.D. McAlester, and Merrill, U.S. Engineers. Capt. C. S. Stewart and Second Lieut. F. U. Farquhar, U. S. Engineers, joined after the army arrived at Fort Monroe.
        The necessary bridge equipage for the operations of a large army had been collected, consisting of bateaux with the anchors and flooring material (French model), trestles, and engineer's tools, with the necessary wagons for their transportation.
        The small number of officers of this corps available rendered it impracticable to detail engineers permanently at the headquarters of corps and divisions. The companies of regular engineers never had their proper number of officers, and it was necessary, as a rule, to follow the principle of detailing engineer officers temporarily whenever their services were required.

TOPOGRAPHICAL ENGINEERS.

        To the corps of topographical engineers was intrusted the collection of topographical information and the preparation of campaign maps. Until a short time previous to the departure of the army for Fort Monroe Lieut. Col. John N. Macomb was in charge of this department, and prepared a large amount of valuable material. He was succeeded by Brig. Gen. A. A. Humphreys, who retained the position throughout the Peninsula campaign. These officers were assisted by Lieuts. H. L. Abbot, O. G. Wagner, N. Bowen, John M. Wilson, and James H. Wilson, Topographical Engineers. This number, being the greatest available, was so small that much of the duty of the department devolved upon parties furnished by Professor Bache, Superintendent of the Coast Survey, and other gentlemen from civil life.
        Owing to the entire absence of reliable topographical maps the labors of this corps were difficult and arduous in the extreme. Notwithstanding the energy and ability displayed by General Humphreys, Lieutenant-Colonel Macomb, and their subordinates, who frequently obtained the necessary information under fire, the movements of the army were sometimes unavoidably delayed by the difficulty of obtaining knowledge of the country in advance. The result of their labors has been the preparation of an excellent series of maps, which will be invaluable to any army traversing the same ground.
        During the campaign it was impossible to draw a distinct line of de-markation between the duties of the two corps of engineers, so that the labors of reconnaissance of roads, of lines of intrenchments, of fields for battle, and of the position of the enemy, as well as the construction of siege and defensive works, were habitually performed by details from either corps, as the convenience of the service demanded.
        I desire to express my high appreciation of the skill, gallantry, and devotion displayed by the officers of both corps of engineers, under the most trying circumstances.
        During the Maryland campaign I united the two corps under Capt. J. C. Duane, U.S. Engineers, and found great advantages from the arrangement.

MEDICAL DEPARTMENT.

        For the operations of the medical department I refer to the reports, transmitted herewith, of Surg. Charles S. Tripler and Surg. Jonathan Letterman, who, in turn, performed the duties of medical director of the Army of the Potomac, the former from August 12, 1861, until July 1, 1862, and the latter after that date. The difficulties to be overcome in organizing and making effective the medical department were very great, arising principally from the inexperience of the regimental medical officers, many of whom were physicians taken suddenly from civil life, who, according to Surgeon Triplet, " had to be instructed in their duties from the very alphabet," and from the ignorance of the line officers as to their relations with the medical officers, which gave rise to confusion and conflict of authority. Boards of examination were instituted, by which many ignorant officers were removed, and by the successive exertions of Surgeons Tripler and Letterman the medical corps was brought to a very high degree of efficiency. With regard to the sanitary condition of the army while on the Potomac, Dr. Tripler says that the records show a constantly increasing immunity from disease. "In October and November, 1861, with an army averaging 130,000 men, we had 7,932 cases of fever of all sorts. Of these about 1,000 were reported as cases of typhoid fever. I know that errors of diagnosis were frequently committed, and therefore this must be considered as the limit of typhoid cases. If any army in the world can show such a record as this, I do not know when or where it was assembled." From September, 1861, to February, 1862, while the army was increasing, the number of sick decreased from 7 per cent. to 6.18 per cent. Of these the men sick in the regimental and general hospitals were less than one-half; the remainder were slight cases, under treatment in quarters. "During this time, so far as rumor was concerned, the army was being decimated by disease every month." Of the sanitary condition of the army during the Peninsular campaign, up to its arrival at Harrison's Landing, Dr. Triplet says:
        During this campaign the army was favored with excellent health. No epidemic disease appeared. Those scourges of modern armies--dysentery, typhus, cholera-were almost unknown. We had some typhoid fever and more malarial fevers, but even these never prevailed to such an extent as to create any alarm. The sick reports were sometimes larger than we cared to have them, but the great majority of the cases reported were such as did not threaten life or permanent disability. I regret that I have not before me the retained copies of the monthly reports, so that I might give accurate satistics. I have endeavored to recover them, but have been unsuccessful. My recollection is that the whole sick report never exceeded 8 per cent. of the force, and this including all sorts of cases, the trivial as well as the severe. The Army of the Potomac must be conceded to have been the most healthy army in the service of the United States.
        His remarks at the conclusion of his report upon our system of medical administration and his suggestions for its improvement are especially worthy of attention.
        The service, labors, and privations of the troops during the seven days' battles had of course a great effect on the health of the army after it reached Harrison's Landing, increasing the number of sick to about 20 per cent. of the whole force. The nature of the military operations had also unavoidably placed the medical department in a very unsatisfactory condition. Supplies had been almost entirely exhausted or necessarily abandoned, hospital tents abandoned or destroyed, and the medical officers deficient in numbers and broken down by fatigue. All the remarkable energy and ability of Surgeon Letterman were required to restore the efficiency of his department, but before we left Harrison's Landing he had succeeded in fitting it out thoroughly with the supplies it required, and the health of the army was vastly improved by the sanitary measures which were enforced at his suggestion.
        The great haste with which the army was removed from the Peninsula made it necessary to leave at Fort Monroe, to be forwarded afterwards, nearly all the baggage and transportation, including medical stores and ambulances, all the vessels being required to transport the troops themselves and their ammunition; and when the Army of the Potomac returned to Washington after General Pope's campaign, and the medical department came once more under Surgeon Letterman's control, he found it in a deplorable condition. The officers were worn-out by the labors they had performed, and the few supplies that had been brought from the Peninsula had been exhausted or abandoned, so that the work of reorganization and resupplying had to be again performed, and this while the army was moving rapidly, and almost in the face of the enemy. That it was successfully accomplished is shown by the care and attention which the wounded received after the battles of South Mountain and Antietam.
        Among the improvements introduced into his department by Surgeon Letterman, the principal are the organization of an ambulance corps, the system of field hospitals, and the method of supplying by brigades, all of which were instituted during the Maryland campaign, and have since proved very efficient.

QUARTERMASTER'S DEPARTMENT.

        On assuming command of the troops in and around Washington I appointed Capt. S. Van Vliet, assistant quartermaster (afterwards brigadier-general), chief quartermaster to my command, and gave him the necessary instructions for organizing his department and collecting the supplies requisite for the large army then called for.
        The disaster at Manassas had but recently occurred, and the army was quite destitute of quartermaster's stores. General Van Vliet with great energy and zeal set himself about the task of furnishing the supplies immediately necessary, and preparing to obtain the still larger amounts which would be required by the new troops, which were moving in large numbers towards the capital. The principal depot for supplies in the city of Washington was under charge of Col. D. H. Rucker, assistant quartermaster, who ably performed his duties. Lieut. Col. R. Ingalls, assistant quartermaster, was placed in charge of the department on the south side of the Potomac. I directed a large depot for transportation to be established at Perryville, on the left bank of the Susquehanna, a point equally accessible by rail and water. Capt. C. G. Sawtelle, assistant quartermaster, was detailed to organize the camp, and performed his duties to my entire satisfaction. Capt. J. J. Dana, assistant quartermaster, had immediate charge of the transportation in and about Washington, as well as of the large number of horses purchased for the use of the artillery and cavalry. The principal difficulties which General Van Vliet had to encounter arose from the inexperience of the majority of the officers of his department in the new regiments and brigades. The necessity of attending personally to minor details rendered his duties arduous and harassing in the extreme. All obstacles, however, were surmounted by the untiring industry of the chief quartermaster and his immediate subordinates, and when the army was prepared to move, the organization of the department was found to be admirable.
        When it was determined to move the army to the Peninsula, the duties of providing water transportation were devolved by the Secretary of War upon his assistant, the Hon. John Tucker. The vessels were ordered to Alexandria, and Lieutenant-Colonel Ingalls was placed in immediate charge of the embarkation of the troops, transportation, and material of every description. Operations of this nature on so extensive a scale had no parallel in the history of our country.
        The arrangements of Lieutenant-Colonel Ingalls were perfected with remarkable skill and energy, and the army and its material were embarked and transported to Fort Monroe in a very short space of time and entirely without loss.
        During the operations on the Peninsula, until the arrival of troops at Harrison's Landing, General Van Vliet retained the position of chief quartermaster, and maintained the thorough organization and efficiency of his department. The principal depots of supplies were under the immediate charge of Lieutenant-Colonels Ingalls and Sawtelle.
        On the 10th of July, 1862, General Van Vliet having requested to be relieved from duty with the Army of the Potomac, I appointed Lieutenant-Colonel Ingalls chief' quartermaster, and he continued to discharge the duties of that office during the remainder of the Peninsula and the Maryland campaigns in a manner which fully sustained the high reputation he had previously acquired.
        The immense amount of labor accomplished, often under the most difficult circumstances, the admirable system under which the duties of the department were performed, and the entire success which attended the efforts to supply so large an army, reflect the highest credit upon the officers upon whom these onerous duties devolved. The reports of General Van Vliet and Lieutenant-Colonel Ingalls, with the accompanying documents, give in detail the history of the department from its organization until I was relieved from the command of the Army of the Potomac.

SUBSISTENCE DEPARTMENT.

        On the 1st of August, 1861, Col. H. F. Clarke, commissary of subsistence, joined my staff, and at once entered upon his duties as chief commissary of the Army of the Potomac. In order to realize the responsibilities pertaining to this office, as well as to form a proper estimate of the vast amount of labor which must necessarily devolve upon its occupant, it is only necessary to consider the unprepared state of the country to engage in a war of such magnitude as the present, and the lack of practical knowledge on the part of the officers with reference to supplying and subsisting a large and at that time unorganized army. Yet notwithstanding the existence of these great obstacles, the manner in which the duties of the commissary department were discharged was such as to merit and call forth the commendation of the entire army.
        During the stay of the Army of the Potomac in the vicinity of Washington, prior to the Peninsular campaign, its subsistence was drawn chiefly from the depots which had been established by the Commissary Department at Washington, Alexandria, Forts Corcoran and Runyon. In the important task of designating and establishing depots of supplies Colonel Clarke was ably seconded by his assistants, Col. Amos Beck-with, commissary of subsistence, U.S. Army; Lieut. Col. George Bell, commissary of subsistence, U.S. Army; Lieut. Col. A. P. Porter, commissary of subsistence, U.S. Army; Capt. Thomas Wilson, commissary of subsistence, U.S. Army; Capt. Brownell Granger, commissary of subsistence, U.S. Volunteers; Capt. W. H. Bell, commissary of subsistence, U.S. Army; Capt. J. H. Woodward, commissary of subsistence, U.S. Volunteers; and Capt. W. R. Murphy, commissary of subsistence, U.S. Volunteers.
        For a full knowledge of the highly creditable manner in which each and all of the above-mentioned officers discharged their duties I invite attention to the detailed report of Colonel Clarke. The remarks and suggestions contained in his report are worthy of attention, as affording valuable rules for the future guidance of the Subsistence Department in supplying armies in the field. The success of the subsistence department of the Army of the Potomac was in a great measure attributable to the fact that the Subsistence Department at Washington made ample provision for sending supplies to the Peninsula, and that it always exercised the most intelligent foresight. It moreover gave its advice and countenance to the officers charged with its duties and reputation in the field, and those officers, I am happy to say, worked with it and together in perfect harmony for the public good. During the entire period that I was in command of the Army of the Potomac there was no instance within my knowledge where the troops were without their rations from any fault of the officers of this department.

ORDNANCE DEPARTMENT

        This very important branch of the service was placed under the charge of Capt. C. P. Kingsbury, Ordnance Corps, colonel and aide-de-camp. Great difficulty existed in the proper organization of the department for the want of a sufficient number of suitable officers to perform the duties at the various headquarters and depots of supply. But far greater obstacles had to be surmounted, from the fact that the supply of small-arms was totally inadequate to the demands of a large army, and a vast proportion of those furnished were of such inferior quality as to be unsatisfactory to the troops and condemned by their officers. The supply of artillery was more abundant, but of great variety. Rifled ordnance was just coming into use for the first time in this country, and the description of gun and kind of projectile which would prove most effective, and should therefore be adopted; was a mere matter of theory. To obviate these difficulties, large quantities of small-arms of foreign manufacture were contracted for; private enterprise in the construction of arms and ammunition was encouraged, and by the time the army was ordered to move to the Peninsula the amount of ordnance and ordnance stores was ample. Much also had been done to bring the quality both of arms and ammunition up to the proper standard. Boards of officers were in session continually during the autumn and winter of 1861 to test the relative merits of new arms and projectiles.
        The reports of these boards, confirmed by subsequent experience in the field, have done much to establish the respective claims of different inventors and manufacturers. During the campaigns of the Peninsula and Maryland the officers connected with the department were zealous and energetic and kept the troops well supplied, notwithstanding the perplexing and arduous nature of their duties. One great source of perplexity was the fact that it had been necessary to issue arms of all varieties and calibers, giving an equal diversity in the kinds of ammunition required. Untiring watchfulness was therefore incumbent upon the officers in charge to prevent confusion and improper distribution of cartridges. Colonel Kingsbury discharged the duties of his office with great efficiency until the -- day of July, 1862, when his health required that he should be relieved. First Lieut. Thomas G. Baylor, Ordnance Corps, succeeded him, and performed his duty during the remainder of the Peninsular and Maryland campaigns with marked ability and success.
        The want of reports from Colonel Kingsbury and Lieutenant Baylor renders it impossible for me to enter at all into the details of the organization of the department.

PROVOST-MARSHAL'S DEPARTMENT.

        Immediately after I was placed in command of the Division of the Potomac, I appointed Col. Andrew Porter, Sixteenth U.S. Infantry, provost-marshal of Washington. All the available regular infantry, a battery, and a squadron of cavalry were placed under his command, and by his energetic action he soon corrected the serious evils which existed and restored order in the city.
        When the army was about to take the field General Porter was appointed provost-marshal-general of the Army of the Potomac, and held that most important position until the end of the Peninsular campaign, when sickness, contracted in the untiring discharge of his duties, compelled him to ask to be relieved from the position he had so ably and energetically filled.
        The provost-marshal-general's department had the charge of a class of duties which had not before in our service been defined and grouped under the management of a special department. The following subjects indicate the sphere of this department:
        Suppression of marauding and depredations, and of all brawls and disturbances, preservation of good order, and suppression of disturbances beyond the limits of the camps.

        Prevention of straggling on the march.
        Suppression of gambling-houses, drinking-houses, or bar-rooms, and brothels.
        Regulation of hotels, taverns, markets, and places of public amusement.
        Searches, seizures, and arrests. Execution of sentences of general courts-martial involving imprisonment or capital punishment. Enforcement of orders prohibiting the sale of intoxicating liquors, whether by tradesmen or sutlers, and of orders respecting passes.
        Deserters from the enemy.
        Prisoners of war taken from the enemy.
        Countersigning safeguards.
        Passes to citizens within the lines and for purposes of trade.
        Complaints of citizens as to the conduct of the soldiers.

        General Porter was assisted by the following-named officers:
        Maj. W. H. Wood, Seventeenth U.S. Infantry; Capt. James Macmillan, acting assistant adjutant-general, Second U.S. Infantry; Capt. W. T. Gentry, Seventeenth U.S. Infantry; Capt. J. W. Forsyth, Eighteenth U.S. Infantry; Lieut. J. W. Jones, Twelfth U.S. Infantry; Lieut. C. F. Trowbridge, Sixteenth U.S. Infantry; and Lieut. C. D. Mehaffey, First U.S. Infantry.
        The provost guard was composed of the Second U.S. Cavalry, Major Pleasonton, and a battalion of the Eighth and Seventeenth U.S. Infantry, Major Willard. After General Porter was relieved Major Wood was in charge of this department until after the battle of Antietam, when Brigadier-General Patrick was appointed provost-marshal-general.

COMMANDANT OF GENERAL HEADQUARTERS.

        When the army took the field, for the purpose of securing order and regularity in the camp of headquarters and facilitating its movements, the office of commandant of general headquarters was created, and assigned to Maj. G. O. Haller, Seventh U.S. Infantry. Six companies of infantry were placed under his orders for guard and police duty. Among the orders appended to this report is the one defining his duties, which were always satisfactorily performed.

JUDGE-ADVOCATE.

        From August, 1861, the position of judge-advocate was held by Col. Thomas T. Gantt, aide-de-camp, until compelled by ill-health to retire, at Harrison's Landing, in August, 1862. His reviews of the decisions of courts-martial during this period were of great utility in correcting the practice in military courts, diffusing true notions of discipline and subordination, and setting before the army a high standard of soldierly honor. Upon the retirement of Colonel Gantt the duties of judge advocate were ably performed by Col. Thomas M. Key, aide-de-camp.

SIGNAL CORPS.

        The method of conveying intelligence and orders, invented and introduced into the service by Maj. Albert J. Myer, Signal Officer, U.S. Army, was first practically tested in large operations during the organization of the Army of the Potomac.
        Under the direction of Major Myer a Signal Corps was formed by detailing officers and men from the different regiments of volunteers and instructing them in the use of the flags by day and torches by night.
        The Chief Signal Officer was indefatigable in his exertions to render his corps effective, and it soon became available for service in every division of the army. In addition to the flags and torches, Major Myer introduced a portable insulated telegraph wire, which could be readily laid from point to point, and which could be used under the same general system. In front of Washington, and on the Lower Potomac, at any point within our lines not reached by the military telegraph, the great usefulness of this system of signals was made manifest. But it was not until after the arrival of the army upon the Peninsula, and during the siege and battles of that and the Maryland campaigns, that the great benefits to be derived from it on the field and under fire were fully appreciated.
        There was scarcely any action or skirmish in which the Signal Corps did not render important services. Often under heavy fire of artillery, and not unfrequently while exposed to musketry the officers and men of this corps gave information of the movements of the enemy and transmitted directions for the evolutions of our own troops. The report of the Chief Signal Officer, with accompanying documents, will give the details of the services of this corps, and call attention to those members of it who were particularly distinguished.

TELEGRAPHIC.

        The telegraphic operations of the Army of the Potomac were superintended by Maj. Thomas T. Eckert, and under the immediate direction of Mr. Caldwell, who was, with a corps of operators, attached to my headquarters during the entire campaigns upon the Peninsula and in Maryland. The services of this corps were arduous and efficient. Under the admirable arrangements of Major Eckert they were constantly provided with all the material for constructing new lines, which were rapidly established whenever the army changed position, and it was not unfrequently the case that the operatives worked under fire from the enemy's guns, yet they invariably performed all the duties required of them with great alacrity and cheerfulness, and it was seldom that I was without the means of direct telegraphic communication with the War Department and with the corps commanders. From the organization of the Army of the Potomac up to November 1, 1862, including the Peninsular and Maryland campaigns, upwards of 1,200 miles of military telegraph line had been constructed in connection with the operations of the army, and the number of operatives and builders employed was about 200.
        To Professor Lowe, the intelligent and enterprising aeronaut, who had the management of the balloons, I was greatly indebted for the valuable information obtained during his ascensions.
        I have more than once taken occasion to recommend the members of my staff, both general and personal, for promotion and reward. I beg leave to repeat these recommendations, and to record their names in the history of the Army of the Potomac as gallant soldiers, to whom their country owes a debt of gratitude, still unpaid, for the courage, ability, and untiring zeal they displayed during the eventful campaigns in which they bore so prominent a part.

Source:  "Official Records of the War of the Rebellion"

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