HEADQUARTERS ARMY OF THE POTOMAC,
March 16, 1862.

SIR: The command to which you have been assigned, by instructions of the President, as military governor of the District of Columbia, embraces the geographical limits of the District, and will also include the city of Alexandria, the defensive works south of the Potomac from the Occoquan to Difficult Creek, and the post of Fort Washington. I inclose a list of the troops and of the defenses embraced in these limits.

General Banks will command at Manassas Junction, with the divisions of Williams and Shields, composing the Fifth Corps, but you should nevertheless exercise vigilance in your front, carefully guard the approaches in that quarter, and maintain the duties of advance guards. You will use the same precautions on either flank.

All troops not actually needed for the police of Washington and Georgetown, for the garrisons north of the Potomac, and for other indicated special duties, should be moved to the south side of the river.

In the center of your front you should post the main body of your troops, and proper proportions at suitable distances towards your right and left flanks. Careful patrols will be made, in order thoroughly to scour the country in front from right to left.

It is specially enjoined upon you to maintain the forts and their armaments in the best possible order, to look carefully to the instruction and discipline of their garrisons, as well as all other troops under your command, and by frequent and rigid inspections to insure the attainment of these ends.

The care of the railways, canals, depots, bridges, and ferries within the above-named limits will devolve upon you, and you are to insure their security and provide for their protection by every means in your power. You will also protect the depots of the public stores and the transit of stores to troops in active service.

By means of patrols you will thoroughly scour the neighboring country south of the Eastern Branch, and also on your right; and you will use every possible precaution to intercept mails, goods, and persons passing unauthorized to the enemy's lines.

The necessity of maintaining good order within your limits, and especially in the capital of the nation, cannot be too strongly enforced.

You will forward and facilitate the movement of all troops destined for the active part of the Army of the Potomac, and especially the transit of detachments to their proper regiments and corps.

The charge of the new troops arriving in Washington and of all troops temporarily there will devolve upon you. You will form them into provisional brigades, promote their instruction and discipline, and facilitate their equipment. Report all arrivals of troops, their strength, composition, and equipment, by every opportunity.

Besides the regular reports and returns which you will be required to render to the Adjutant-General of the Army, you will make to these headquarters a consolidated report of your command every Sunday morning and monthly returns on the first day of each month.

The foregoing instructions are communicated by command of Major-General McClellan.

S. WILLIAMS,

Assistant Adjutant-General.

Brigadier Gene. J. S. WADSWORTH,

Military Governor of the District of Columbia.

The Secretary of War had expressed a desire that I should communicate to the War Department my designs with regard to the employment of the Army of the Potomac in an official form. I submitted, on the 19th of March, the following:

HEADQUARTERS ARMY OF THE POTOMAC,
Theological Seminary, Va., March 19, 1862.

SIR: I have the honor to submit the following notes on the proposed operations of the active portion of the Army of the Potomac.

The proposed plan of campaign is to assume Fort Monroe as the first base of operations, taking the line of Yorktown and West Point upon Richmond as the line of operations, Richmond being the objective point. It is assumed that the fall of Richmond involves that of Norfolk and the whole of Virginia; also that we shall fight a decisive battle between West Point and Richmond, to give which battle the rebels will concentrate all their available forces, understanding, as they will, that it involves the fate of their cause. If therefore follows -.

1st. That we should collect all our available forces and operate upon adjacent lines, maintaining perfect communication between our columns.

2nd. That no time should be lost in reaching the field of battle.

The advantages of the Peninsula between York and James Rivers are too obvious.