George B. McClellan to Seth Williams, March 8, 1862

Ordered, That no change of the base of operations of the Army of the Potomac shall be made without leaving in and about Washington such a force as, in the opinion of the General-in-Chief and the commanders of army corps, shall leave said city entirely secure. PA

That no more than two army corps (about fifty thousand. troops) of said Army of the Potomac shall be moved en route for a new base of operations until the navigation of the Potomac from Washington to the Chesapeake Bay shall be freed from enemy’s

batteries and other obstructions, or until the President shall hereafter give express permission. y

That any movement as aforesaid, en route for.a new base of operations, which may be ordered by the General-in-Chief, and which may be intended to move upon the Chesapeake Bay, shall begin to move upon the bay as early as the 18th March instant, — and the General-in-Chief shall be responsible that it moves as early as that day. – ——

Ordered, That the Army and Navy co-operate in an immediate effort to capture the enemy’s batteries upon the Potomac between Washington and the Chesapeake Bay.

L. THOMAS, Adjutant-General. i After what has been said already in regard to the effect of a movement to the Lower Chesapeake, it is unnecessary for me to comment

upon this document, fùrther than to say that the time of beginning the movement depended upon the state of readiness of the transports, the . entire control of which had been placed by the Secretary of War in the hands of one of the Assistant Secretaries, and not under the Quartermaster-General, so that, even if the movement were not impeded by the condition imposed in regard to the batteries on the Potomae, it could not have been in my power to begin it before the 18th of March, unless DE Assistant Secretary of War had completed his arrangements by that time.

Meanwhile important events were occurring which materially modified the designs for the subsequent campaign. The appearance of the Merrimac off Old Point Comfort, and.the encounter with the United States squadron on the 8th of March, threatened serious derangement

‘ of the plan for the Peninsula movement. But the engagement between the Monitor and Merrimac on the 9th of March demonstrated so satisfactorily the power of the former, and the other naval preparations were

. 80 extensive and formidable, that the security of Fort Monroe as a base

of operations was placed beyond a doubt, and although the James River was closed to us, the York River with its tributaries was still open as a line of water communication with the Fortress. The general plan, therefore, remained undisturbed, although less promising in its details than when the James River was in our control.

. On Sunday, the 9th of March, information from various sources made * it apparent that the enemy was evacuating his positions at Centreville. and Manassas as well as on the Upper and Lower Potomac. The President and Secretary of War were present when the most positive information reached me, and I expressed to them my intention to cross the river immediately, and there gain the most authentic information prior to determining whai course to pursue. :

The retirement of the enemy towards Richmond had been expected as the natural consequence of the movement to the Peninsula, but ` their adoption of this course immediately on ascertaining that such a movement was intended, while it relieved me from the results of the undue anxiety of my superiors and attested the character of the design, was unfortunate in that the then almost impassable roads between our

positions and theirs deprived us of the opportunity for inflicting damage

usually afforded by the withdrawal of a large army in the face of a pow- . erful adversary.

The retirement of the enemy and the occupation of the abandoned positions which necessarily followed presented an opportunity for the troops to gain some experience on the march and bivouac preparatory to the campaign, and to get rid of the superfluous baggage and other “impedimenta” which accumulates so easily around an army encamped for a long time in one locality.

A march to Manassas and back could produce no delay in embarking for the Lower Chesapeake, as the transports could not be ready for some

_ time, and it afforded a good intermediate step between the quiet and

comparative comfort of the camps around Washington and the rigors of active operations, besides accomplishing the important object of de- termining the positions, and perhaps the future designs, of the enemy,

with the possibility of being able to harass their rear. I therefore issued orders during the night of the 9th of March for a

general movement of the army the next morning towards Centreville

and Manassas, sending in advance two regiments of cavalry under Colonel Averell, with orders to reach Manassas if possible, ascertain the exact condition of affairs, and do whatever he could to retard and annoy the enemy if really in retreat; at the same time I telegraphed to the Secretary of War that it would be necessary to defer the organization of the army eorps until the eompletion of the projected advance upon Manassas, as the divisions could not be brought together in time. The Secretary replied, requiring immediate compliance with the President’s order; but on my again representing that this would compel the abandonment or postponement of the movement to Manassas, he finally consented to its postponement.

Atnoon on the 10th of March the cavalry advance reached the enemy’s lines at Centreville, passing through his recently-occupied camps and

works, and finding still burning heaps of military stores and much valuable property. – Immediately after being assigned to the command of the troops around

TOES – d Neo ES up J

Washington I organized a secret-service force, under Mr. E. J. Allen.

a very éxperienced and efficient person. This force, up to the time I.

was relieved from command, was continually occupied in procuring from all possible sources-information regarding the strength, positions, and movements of the enemy. (Mr. Allen Pinkerton was the trustworthy and efficient chief of the secret-service corps mentioned under the assumed name of E. J. Allen.) = All spies, “contrabands,” deserters, refugees, and many prisoners of war coming into our lines from the front were carefully examined, first – by the outpost and division commanders, and then by my chief of staff and the provost-marshal-general. Their statements, taken in writing, and in many cases under oath, from day to day, for a long period, previous to the evacuation of Manassas, comprised a mass of evidence which, –

by careful digests and collations, enabled me to estimate with considerable accuracy the strength of the enemy before us. Summaries showing the character and results of the labors of the secret-service force

accompany this report, and I refer to them for the facts they contain, and as a measure of the ignorance which led some journals at that time, and persons in high office, unwittingly to trifle with the reputation of

an army, and to delude the country with quaker-gun stories of the defenses and gross understatements of the numbers of the enemy.

The following orders were issued for the examination of persons eoming from the direction of the enemy: :

[ CIRCULAR.] HEADQUARTERS ARMY OF THE Potomac, Washington, December 16, 1861.

The Major-Genéral Commanding directs that hereafter all deserters, prisoners, spies, “”contrabands,” and all other persons whatever coming or brought within our lines from Virginia shall be taken immediately to the quarters of the commander of the division within whose lines they may come or be brought, without previous examination by any one, except so far as may be necessary for the officer commanding the advance guard to elicit information regarding his particular post; that the division commander examine, all such persons himself, or delegate such duty to a proper officer of his staff, and allow no other persons to hold any communication with them; that he then immediately send them, with a sufficient guard, to the provost-marshal in this city for

further examination and safe-keeping, and that stringent orders be given to all guards –

having such persons in charge not to hold any communication with them whatever; and, further, that the information elicited from such persons shall be immediately communicated to the major-general commanding or to the chief of staff, and to-no other person whatever. , :

The Major-General Commanding further directs that a sufficient guard be placed around every telegraph station pertaining to this army, and that such guards be iny

structed not to allow any person, except the regular telegraph corps, general officers, –

and such staff officers as may be authorized by their chief, to enter or loiter áround said stations within hearing of the sound of the telegraph instruments.

By command of Major-General McClellan :