Report of Major General George B. McClellan Upon the Organization of the Army of the Potomac and Its Campaigns in Virginia and Maryland (excerpt from the 1863 report covering the period of 1861-1862)

Major General George B. McClellan, Commanding Officer, U.S. Army of the Potomac, 1861 (Matthew Brady, U.S. Library of Congress, public domain).

Letter from the Secretary of War, Transmitting The report of Major General George B. McClellan upon the organization of the Army of the Potomac, and its campaigns in Virginia and Maryland, from July 26, 1861, to November 7, 1862.


February 19, 1864.

Resolved, That there be printed, for the use of the members of this House, ten thousand additional copies of General McClellan’s report.


Washington City, D.C., December 22, 1863.

SIR: In compliance with the resolution dated December 16, 1863, I have the honor to communicate herewith “the report made by Major General George B. McClellan, concerning the organization and operations of the army of the Potomac while under his command, and of all army operations while he was commander-in-chief.”

I am, sir, very respectfully, your obedient servant,

EDWIN M. STANTON, Secretary of War.

Hon. Schuyler Colfax, Speaker House of Representatives



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 Phillippi, 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 the valley.

I had determined to proceed to the relief of the upper Kanawha valley, as soon as provision was made for the permanent defence [sic] of the mountain passes leading from the east into the region under 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 my command to Brigadier General Rosecrans, and repair at once to Washington.

I had already caused reconnoissances [sic] to be made for intrenchments [sic] at the Cheat Mountain pass; also on the Hunterville 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 in 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 defence [sic] of Washington, from July, 1861, to March, 1862. The campaign on the Peninsula, and that in Maryland.

* Editor’s Note: The excerpt presented here for 47th Pennsylvania Volunteers: One Civil War Regiment’s Story of Major General George B. McClellan’s report regarding his actions as commanding general of the U.S. Army of the Potomac contains only the first two of the aforementioned sections of his report since the 47th Pennsylvania Volunteers engaged only in the first two functions under McClellan before being shipped to Florida in January 1862 to garrison Fort Taylor in Key West. (The 47th Pennsylvania formally mustered in at Camp Curtin in Harrisburg, Pennsylvania during late August and early September 1861, and received basic training there before being transported by rail to the Washington, D.C. area, where they initially made camp on the Kalorama Heights near Georgetown beginning 21 September – the same day on which the 47th Pennsylvania was reviewed by McClellan.)

McClellan’s full report is available online via this link.

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 fourth of August, 1861, I addressed to the President the following memorandum, prepared at this request:


The object of the present war differs from those in which nations are 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 this 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 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 connexion [sic] with the movement on the Mississippi, would go far towards determining the evacuation of Virginia by the rebels. In the mean time [sic] 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 re-open 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 no 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 five to ten thousand from Ohio and Indiana, should, under proper management, suffice for its protection.

When we have re-organized our main army here, 10,000 men ought to be enough to protect the Baltimore and Oho 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 defence [sic] of Washington.

For the main army of operations I urge the following composition:

25 regiments of infantry, say . . . . . . . . . . . . . . . 225,000 men.
100 field batteries, 600 guns . . . . . . . . . . . . . . .   15,000 “ .
28 regiments of cavalry  . . . . . . . . . . . . . . . . . . .   25,000 “.
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 available 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, 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 co-operate 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 new strategic points and lines of operations.

It is intended to overcome this difficulty by the partial operations suggested, and such others as the 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 defence [sic], to diminish its contingent to the confederate army.

The proposed movement down the Mississippi will produce important results in this connexion [sic]. 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 [the] 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 connecting 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 ultimate 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 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 further 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.

* Editor’s Note: During their long tenure of Civil War service (from 1861 to early 1866), the 47th Pennsylvania Volunteers would call multiple duty stations in the Deep South home, including Charleston (South Carolina), Savannah (Georgia), and New Orleans (Louisiana).

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 my 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 supplies as may there be obtained.

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 [sic] 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 defence [sic], 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 his 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:

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 state 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 army, 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 us 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 [sic]. It is plain, therefore, that to insure success, or to render it reasonably certain, the active army should not number less than the 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:

Column of active operations . . . . . . . . . . . . . . . 150,000 men, 400 guns.
Garrison of the city of Washington . . . . . . . . .    75,000 “           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, 4268 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 this 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 be 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 enrolment [sic], organization and armament of new batteries and regiments of infantry.

Sixth, that all of 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.

Hon. Simon Cameron,
Secretary of War.

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 McDowall still existed, and the troops were stationed at and in rear of Fort Corcoran, Arlington, and Fort Albany, at Fort Runyon, Roach’s Mills, Cole’s Mills, 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 defence [sic], and entirely inadequate in numbers and condition to defend the long line from Fort Corcoran to Alexandria.

Chain Bridge across the Potomac above Georgetown looking toward Virginia, 1861 (The Illustrated London News, public domain).

On the Maryland side of the river, upon the heights overlooking the Chain bridge, two regiments were stationed, where commanders were independent of each other.

There were no troops on the important Tenallytown road, or on the roads entering the city from the south.

The camps were located without regard to the purposes of defence [sic] or instruction, the roads were not picketed, and there was no attempt at an organization into brigades.

In no quarter were the dispositions for defence [sic] 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 têtes du 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 co-operated with me in the labor of bringing order out of confusion, re-assigning troops and commands, projecting and throwing up defensive works, receiving and organizing, equipping and providing for the new levies arriving in 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 Colonel 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, now 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. Brigadier General F. J. Porter was at first assigned to the charge of the provisional brigades. Brigadier General A. E. Burnside was the next officer assigned this duty, from which, however, he was soon relieved by Brigadier General S. Casey, who continued in charge of the newly arriving regiments until the army of the Potomac departed for the Peninsula, in March, 1862. [* Editor’s Note: The 47th Pennsylvania was attached to the Army of the Potomac from 21 September 1861 until early 1862 when it was shipped to the Deep South on 27 January 1862 to garrison Fort Taylor in Key West, Florida.] The newly arriving artillery troops reported to Brigadier General William F. Barry, the chief of artillery, and the cavalry to Brigadier General 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
“ sick . . . . . . . . . . . . . . . . . . . . . . . . . . . .       9,290
“ in confinement . . . . . . . . . . . . . . . . . . . .    1,156
Grand aggregate  . . . . . . . . . . . . . . . . . . . 152,051

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

Union Army Troop Strength, December 1861-March 1862 (Major-General George McClellan’s 1863 Report on the Organization of the Army of the Potomac, public domain).

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

Union Army Troop Strength, April-July 1862 (Major-General George McClellan’s 1863 Report on the Organization of the Army of the Potomac, public domain).


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 permanently 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 offices 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 instrusted [sic] 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 as armed with a sabre 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 Brigadier General George Sykes, major third infantry United States army.


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 army was confided to Major (afterwards Brigadier General) 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, it will be observed that the following principles were adopted as the basis of organization:

“1. That the proportion of artillery should be in the proportion of at least two and one-half pieces to 1,000 men, to be expanded, if possible, to three pieces to 1,000 men.

“2. That the proportion of rifled guns should be restricted to the system of the United States ordnance department; and of Parrott and the ‘smooth bores’ (with the exception of a few howitzers for special service) to be exclusively the twelve-pounder gun, of the model of 1857, variously called the ‘gun-howitzer,’ the ‘light twelve-pounder,’ or the ‘Napoleon.’

“3. That each field battery should, if practicable, be composed of six guns, and none to be less than four guns, and in all cases the guns of each battery should be of uniform calibre [sic].

“4. That the field batteries were to be assigned to divisions, and not to brigades, and in the proportion of four to each division, of which one was to be a battery of regulars, the remainder of volunteers, the captain of the regular battery to be the commandant of artillery of the division. In the event of several divisions constituting an army corps, at least one-half of the divisional artillery was to constitute the reserve artillery of the corps.

“5. That the artillery reserve of the whole army should consist of one hundred guns, and should comprise, besides a sufficient light ‘mounted batteries,’ all the guns of position, and until the cavalry were massed, all the horse artillery.

“6. That the amount of ammunition to accompany field batteries was not to be less than four hundred rounds per gun.

“7. A siege train of fifty pieces. This was subsequently expanded, for special service at the siege of Yorktown, to very nearly one hundred pieces, and comprised the unusual calibres [sic] and enormously heavy weight of metal of two 200-pounds, five 100-pounders, and ten 13-inch sea-coast mortars.”

As has been before stated, the chief of artillery reports the whole of the field artillery of the army of the Potomac, July 28, 1861, as comprised of nine imperfectly equipped batteries, of thirty guns, 650 men, and 40 horses. In March, 1862, when the whole army took the field, it consisted of ninety-two batteries, of 520 guns, 12,500 men, and 11,000 horses, fully equipped and in readiness for active field service; of the whole force thirty batteries were regulars, and sixty-two batteries volunteers. [* Editor’s Note: As mentioned previously, the 47th Pennsylvania Volunteers were attached to the U.S. Army of the Potomac only from mid-September 1861 through early January 1862; as a result, they were not part of this March 1862 mobilization. At that time, they were stationed at Fort Taylor, in Key West, Florida.] During the short period of seven months, all of this immense material was issued by the ordnance department a placed in the hands of the artillery troops after their arrival in Washington. About one-fourth of all the volunteer batteries brought with them from their respective States a few guns and carriages, but they were nearly all of such peculiar calibre [sic] as to lack uniformity with the more modern and more serviceable ordnance with which the other batteries were armed, and they therefore had to be withdrawn and replaced by more suitable material. While about one-sixth came supplied with horses and harness, less than one-tenth were apparently fully equipped for service when they reported; and every one of these required the supply of many deficiencies of material, and very extensive instruction in the theory and practice of their special arm….

When there were so many newly organized volunteer field batteries, many of whom received their first and only instruction in the intrenched [sic] camps covering Washington during the three or four inclement months of the winter of 1861-’62, there was, of course, much to be improved. Many of the volunteer batteries, however, evinced such zeal and intelligence, and availed themselves so industriously of the instructions of the regular officers, their commanders, and the example of the regular batteries, their associates, that they made rapid progress, and attained a degree of proficiency highly creditable.

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. – 23d, 25th, 35th, and 37th regiments New York volunteers.

Brigadier General Heintzelman’s brigade. – 5th regiment Maine volunteers, 16th, 26th, and 27th regiments New York volunteers, and Tidball’s battery (A), 2d United States artillery.

Brigadier General W. T. Sherman’s brigade. – 9th and 14th regiments Massachusetts volunteers, DeKalb regiment New York volunteers, 4th regiment Michigan volunteers, Hamilton’s battery (E), 3d United States artillery, and company I, 2d United States cavalry.

Brigadier General Kearney’s brigade. – 1st, 2d, and 3d regiments New Jersey volunteers, Green’s battery (G), 2d United States artillery, and company G, 2d United States cavalry.

Brigadier General Hooker’s brigade. – 1st and 11th regiments Massachusetts volunteers, 2d regiment New Hampshire volunteers, and 26th regiment Pennsylvania volunteers.

Colonel Keys’s brigade. –22d, 24th, and 30th regiments New York volunteers, and 14th regiment New York State militia.

Brigadier General Franklin’s brigade. – 15th, 18th, 31st, and 32d regiments New York volunteers, Platt’s battery (M), 2d United States artillery, and company C, New York (Lincoln) cavalry.

Colonel Blenker’s brigade. – 8th and 27th regiments New York volunteers, 27th regiment Pennsylvania volunteers, and Garibaldi guard, New York volunteers.

Colonel Richardson’s brigade. – 12th regiment New York volunteers, and 2d and 3d regiments Michigan volunteers.

Brigadier General Stone’s brigade. – 34th and Tammany regiments New York volunteers, 1st regiment Minnesota volunteers, and 2d regiment New York State militia.

Colonel William F. Smith’s brigade. –2d and 3d regiments Vermont volunteers, 6th regiment Maine volunteers, 33d regiment New York volunteers, company H, 2d United States cavalry, and Captain Mott’s New York battery.

Colonel Couch’s brigade. – 2d regiment Rhode Island volunteers, 7th and 10th regiments Massachusetts volunteers, and 36th regiment New York volunteers.

The 2d regiment Maine, the 2d regiment Wisconsin, and the 13th regiment New York volunteers, stationed at Fort Corcoran.

The 21st regiment New York volunteers, stationed at Fort Runyon.

The 17th 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….

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

1. Brigadier General George Stoneman’s cavalry command. – 5th United States cavalry, 4th Pennsylvania cavalry, Oneida cavalry (one company), 11th Pennsylvania cavalry (Harlan’s), and Barker’s Illinois cavalry, (one company).

2. Colonel H. J. Hunt’s artillery reserve. – Batteries L, A, and B, 2d United States artillery, batteries K and F, 3d United States artillery, battery K, 4th United States artillery, battery H, 1st United States artillery, and battery A, 5th United States artillery.

3. City Guard, Brigadier General Andrew Porter:

Cavalry. – Companies A and E, 4th United States cavalry.

Artillery. – Battery K, 5th United States artillery.

Infantry. – 2d and 3d battalions United States infantry, 8th and 1st companies United States infantry, and Sturgis’s rifles (Illinois volunteers).

4. Banks’s Division:

Cavalry. – Four companies 3d regiment New York cavalry (Van Allen’s).

Artillery. – Best’s battery E, 4th United States artillery, detachment 9th New York artillery, Matthew’s battery E, 1st Pennsylvania artillery, Tompkins’s battery A, 1st Rhode Island artillery.

Infantry. – Abercrombie’s brigade: 12th Massachusetts, 12th and 16th Indiana, and 30th Pennsylvania volunteers. Stiles’s brigade: 3d Wisconsin, 29th Pennsylvania, and 13th Massachusetts volunteers, and 9th New York State militia. Gordon’s brigade: 2d Massachusetts, 28th and 19th New York, 5th Connecticut, 46th and 28th Pennsylvania, and 1st Maryland volunteers.

McDowell’s Division:

Cavalry. – 2d New York cavalry (Harris’s Light), Colonel Davis.

Artillery. – Battery M, 2d, and battery G, 1st United States artillery.

Infantry. – Keys’s brigade: 14th New York State militia, and 22d, 24th, and 30th New York volunteers. Wadsworth’s brigade: 12th, 21st, 23d, and 35th New York volunteers. King’s brigade: 2d, 6th, and 7th Wisconsin, and 19th Indiana volunteers.

Heintzelman’s Division:

Cavalry. – 1st New Jersey cavalry, Colonel Halsted.

Artillery. – Thompson’s battery, C, United States artillery.

Infantry. – Richardson’s brigade: 2d, 3d, and 5th Michigan, and 37th New York volunteers. Sedgwick’s brigade: 3d and 4th Maine, and 38th and 40th New York volunteers. Jameson’s brigade: 32d, 63d, 61st, and 45th Pennsylvania volunteers, and Wild Cat reserves (Pennsylvania volunteers).

F. J. Porter’s Division:

Cavalry. – 3d Pennsylvania cavalry, Colonel Averill, and 8th Pennsylvania cavalry, Colonel Gregg.

Artillery. – Battery E, 2d and battery E (later transferred to Sherman’s division), 3d United States artillery.

Infantry. – Morell’s brigade: 33d Pennsylvania, 4th Michigan, 9th Massachusetts, and 4th New York volunteers. Martindale’s brigade: 13th New York, 2d Maine, and 18th Massachusetts volunteers, and DeKalb regiment New York volunteers. Butterfield’s brigade: 50th New York, 83d Pennsylvania (Colonel McLean), 17th and 25th New York volunteers, and Stockton’s independent Michigan regiment.

Franklin’s Division:

Cavalry. – 1st New York cavalry, Colonel McReynolds.

Artillery. – Batteries D and G, 2d United States artillery, and Hexamer’s battery (New Jersey volunteers).

Infantry. – Kearney’s brigade: 1st, 2d, 3d, and 4th New Jersey volunteers. Slocum’s brigade: 16th, 26th, and 27th New York, and 6th Maine volunteers. Newton’s brigade: 15th, 18th, 31st, and 32d New York volunteers.

Stone’s Division:

Cavalry. – Six companies 3d New York (Van Allen) cavalry.

Artillery. – Kirby’s battery I, 1st United States, Vaughn’s battery B, 1st Rhode Island artillery, and Bunting’s 6th New York independent battery.

Infantry. – Gorman’s brigade: 2d New York State militia, 1st Minnesota, 15th Massachusetts, and 34th New York volunteers, and Tammany regiment (New York volunteers). Lander’s brigade: 19th and 20th Massachusetts, and 7th Michigan volunteers, and a company of Massachusetts sharpshooters. Baker’s brigade: Pennsylvania volunteers, 1st, 2d, and 3d California.

Buell’s Division:

Artillery. – Batteries D and H, 1st Pennsylvania artillery.

Infantry. – Couch’s brigade: 2d Rhode Island, 7th and 10th Massachusetts, and 36th New York volunteers. Graham’s brigade: 23d and 31st Pennsylvania, and 67th (1st Long Island) and 65th (1st United States chasseurs) New York volunteers. Peck’s brigade: 13th and 21st Pennsylvania, and 62d (Anderson Zouaves) and 55th New York volunteers.

McCall’s Division:

Cavalry. – 1st Pennsylvania reserve cavalry, Colonel Bayard.

Artillery. – Easton’s battery A, Cooper’s battery B, and Kein’s battery G, 1st Pennsylvania artillery.

Infantry – Meade’s brigade: 1st rifles Pennsylvania reserves, 4th, 3d, 7th, 11th, and 2d Pennsylvania reserve infantry. [Unnamed] brigade: 5th, 1st, and 8th Pennsylvania reserve infantry. [Unnamed] brigade: 10th, 6th, 9th, and 12th Pennsylvania reserve infantry.

Hooker’s Division:

Cavalry. – Eight companies 3d Indiana cavalry, Lieutenant Colonel Carter.

Artillery. – Elder’s battery E, 1st United States artillery.

Infantry. – [Unnamed] brigade: 1st and 11th Massachusetts, 2d New Hampshire, 26th Pennsylvania, and 1st Michigan volunteers. Sickles’s brigade: 1st, 2d, 3d, 4th, and 5th regiments Excelsior brigade, New York volunteers.

Blenker’s Brigade:

Cavalry. – 4th New York cavalry (mounted rifles), Colonel Dickel.

Artillery. – One battery.

Infantry. – 8th and 9th New York, 27th and 35th Pennsylvania volunteers, Garibaldi guard and Cameron rifles (New York volunteers).

Smith’s Division:

Cavalry. – 5th Pennsylvania cavalry (Cameron dragoons), Colonel Friedman.

Artillery. – Ayres’s batter F, 5th United States artillery, Mott’s 2d New York independent battery, and Barr’s battery E, 1st Pennsylvania artillery.

Infantry. – [Unnamed] brigade: 2d, 3d, 4th, and 5th Vermont volunteers. Stevens’s brigade: 35th and 49th New York and 6th Maine volunteers, and *79th New York State militia. Hancock’s brigade: *47th and 49th Pennsylvania, 43d New York, and 5th Wisconsin volunteers. Companies B and E, Berden’s sharpshooters. [* Editor’s Note: According to this edition of McClellan’s report: “The 79th New York state militia, the 47th Pennsylvania volunteers, and the Round-Head regiment [shown below under “Casey’s provisional brigades,”] were transferred to General Sherman’s expedition.” However, reports by other Union military leaders (including those in charge of the 47th Pennsylvania), and letters and diary entries penned by enlisted men from the 47th during this time show that the 47th Pennsylvania Volunteers continued to assist in the defense of Washington, D.C. from the time of their arrival in the Washington, D.C. area 21 September 1861 until they sailed for Florida on 27 January 1862.]

Casey’s provisional brigades. – 5th, 6th, and 7th New Jersey volunteers, *Round-Head regiment, (Pennsylvania volunteers), battalion District of Columbia volunteers, 40th Pennsylvania, 8th New Jersey, and 4th New Hampshire volunteers.

5. Garrison of Alexandria. – Brigadier General Montgomery, military governor. Cameron guard (Pennsylvania volunteers):

Garrison of Fort Albany. – 14th Massachusetts volunteers.

Garrison of Fort Richardson. – 4th Connecticut volunteers.

Garrison of Fort Washington. – Company D, 1st United States artillery, companies H and I, 37th New York volunteers, and United States recruits unassigned.

6. Dix’s Division, Baltimore:

Cavalry. – Company of Pennsylvania cavalry.

Artillery. – Battery I, 2d United States artillery, 2d Massachusetts light battery, and a battery of New York artillery.

Infantry. – 3d, 4th, and 5th New York, 17th and 25th Massachusetts, 21st Indiana, 6th Michigan, 4th Wisconsin, 7th Maine, 2d Maryland battalion, and Reading city guard, 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 officer 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 Colonel 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 Brigadier General S. Williams, assisted by Lieutenant Colonel James A. Hardie, aide-de-camp. Their management of the department during the organization of the army in the fall and winter of 1862, and during its subsequent operations in the field, was excellent.

They were, during the entire period, assisted by Captain Richard B. Irwin, aide-de-camp, and during the organization of the army by the following-named officers: Captains Joseph Kirkland, Arthur McClellan, M. T. McMahon, William P. Mason, and William F. Biddle, aides-de-camp….

* Editor’s Note: Post-war, Richard B. Irwin went on to pen a history of the Civil War operations of the U.S. Army’s 19th Corps – to which the 47th Pennsylvania was attached for much of 1864.


For the operations of the medical department I refer to the reports, transmitted herewith, of Surgeon Charles S. Tripler and Surgeon 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 Tripler, “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 percent 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…. 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 suggestion for its improvement, are especially worthy of attention….

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.


On assuming command of the troops in and around Washington, I appointed Captain S. Van Vliet, assistant quartermaster, (afterwards brigadier general,) chief quartermaster to my command, and gave him the necessary instructions for organizing his department, and colleting 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 Colonel D. H. Rucker, assistant quartermaster, who ably performed his duties to my entire satisfaction. Captain 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….


On the 1st of August, 1861, Colonel H. F. Clark, 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 way 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 Peninsula 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, Colonel Amos Beckwith, commissary of subsistence, U.S.A.; Lieutenant Colonel George Bell, commissary of subsistence, U.S.A.; Lieutenant Colonel A. P. Porter, commissary of subsistence, U.S.A.; Captain Thomas Wilson, commissary of subsistence, U.S.A.; Captain Brownell Granger, commissary of subsistence, U.S. volunteers; Captain W. H. Bell, commissary of subsistence, U.S.A.; Captain J. H. Woodward, commissary of subsistence, U.S. volunteers; and Captain 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 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 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.


This very important branch of the service was placed under the charge of Captain 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….


Immediately after I was placed in command of the “Division of the Potomac,” I appointed Colonel Andrew Porter, 16th regiment 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 Peninsula 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 or 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 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: Major W. H. Wood, 17th United States infantry; Captain James McMillom, acting assistant adjutant general, 17th United States infantry; Captain W. T. Gentry, 17th United States infantry; Captain J. W. Forsurth, 18th United States infantry; Lieutenant J. W. Jones, 12th United States infantry; Lieutenant C. F. Trowbridge, 16th United States infantry; and Lieutenant C. D. Mehaffey, 1st United States infantry….


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 Major G. O. Haller, 7th United States infantry. Six companies of infantry were placed under his command for guard and police duty. Among the orders appended to this report is the one defining his duties, which were always satisfactorily performed.


From August, 1861, the position of judge advocate was held by Colonel 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 unity 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 Colonel Thomas M. Key, aide-de-camp.


The method of conveying intelligence and orders, invented and introduced into the service by Major Albert J. Myer, signal officer United States 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.


The telegraphic operations of the army of the Potomac were superintended by Major Thomas J. Ecker, 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 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 Peninsula and Maryland campaigns, upwards of twelve hundred (1,200) miles of military telegraph line had been constructed in connexion [sic] with the operations of the army, and the number of operatives and builders employed was about two hundred, (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….


On the 15th of October the main body of the army of the Potomac was in the immediate vicinity of Washington, with detachments on the left bank of the Potomac as far down as Liverpool point, and as far up as Williamsport and its vicinity. The different divisions were posted as follows: Hooker at Budd’s ferry, Lower Potomac; Heintzelman at Fort Lyon and vicinity; Franklin near the theological seminary; Blenker near Hunter’s chapel; McDowell at Upton’s hill and Arlington; F. J. Porter at Hall’s and Miner’s hills; Smith at Mackall’s hill; McCall at Langley; Buell at Tennallytown, Meridian hill, Emory’s chapel, &c., on the left bank of the river; Casey at Washington; Stoneman’s cavalry at Washington; Hunt’s artillery at Washington; Banks at Darnestown, with detachments at Point of Rocks, Sandy Hook, Williamsport, &c.; Stone at Poolsville; and Dix at Baltimore, with detachments on the Eastern Shore.

On the 19th of October, 1861, General McCall marched to Drainsville with his division, in order to cover reconnoissances [sic] to be made in all directions the next day, for the purpose of learning the position of the enemy, and of covering the operations of the topographical engineers in making maps of that region.

On the 29th, acting in concert with General McCall, General Smith pushed strong parties to Freedom hill, Vienna, Flint hill, Peacock hill, &c., to accomplish the same purpose in that part of the front. These reconnoissances [sic] were successful….

The records of the War Department show my anxiety and efforts to assume active offensive operations in the fall and early winter. It is only just to say, however, that the unprecedented condition of the roads and Virginia soil would have delayed an advance till February, had the discipline, organization, and equipment of the army been as complete at the close of the fall as was necessary, and as I desired and labored against every impediment to make them….

On the first of November … I was called to relieve Lieutenant General Scott in the chief and general command of the armies of the Union. The direction and nature of this coast expedition, therefore, were somewhat changed, as will soon appear in the original plan submitted to the Secretary of War, and the letter of instructions later issued to General Burnside, its commander. The whole country indeed had now become the theatre of military operations from the Potomac to beyond the Mississippi, and to assist the navy in perfecting and sustaining the blockade, it became necessary to extend these operations to points on the sea-coast, Roanoke island, Savannah, and New Orleans. It remained also to equip and organize the armies of the west, whose condition as little better than that of the army of the Potomac had been. The direction of the campaigns in the west, and of the operations upon the seaboard, enabled me to enter upon larger combinations and to accomplish results, the necessity and advantage of which had not been unforeseen, but which had been beyond the ability of the single army formerly under my command to effect….


…. I should remark that during the fall and winter of 1861-’62, while the army of the Potomac was in position in front of Washington, reconnoissances [sic] were made from time to time, and skirmishes frequently occurred, which were of great importance in the education of the troops, accustoming them to the presence of the enemy, and giving them confidence under fire. There were many instances of individual gallantry displayed in these affairs….

* Editor’s Note: The remainder of McClellan’s report details Union military activities with which the 47th Pennsylvania Volunteers had no involvement, and has been omitted here in order to ensure that content presented on this website remains relevant to the primary purpose of this project – documenting the history of the 47th Regiment, Pennsylvania Volunteer Infantry. For those interested in reading the remainder of McClellan’s report, it may be found online at this link.



1. Letter from the Secretary of War, Transmitting the report of Major General George B. McClellan upon the organization of the Army of the Potomac, and its campaigns in Virginia and Maryland, from July 26, 1861, to November 7, 1862. Washington, D.C.: Government Printing Office (Ex. Doc. No. 15 produced for the 38th Congress, 1st Session, U.S. House of Representatives), 1864.

2. Snyder, Laurie. About the 47th Pennsylvania Volunteers, in 47th Pennsylvania Volunteers: One Civil War Regiment’s Story, retrieved online 1 January 2018.

3. Wharton, Henry. Letters from the Sunbury Guards. Sunbury, Pennsylvania: Sunbury American, 1861-1862.