C.

HEADQUARTERS ARMY OF THE POTOMAC,
March 16, 1862.

Major General N. P. BANKS,

Commanding Fifth Corps, Army of the Potomac:

SIR: You will post your command in the vicinity of Manassas, intrench yourself strongly, and throw cavalry pickets well out to the front.

Your first care will be the rebuilding of the railway from Washington to Manassas and to Strasburg, in order to open your communications with the valley of the Shenandoah. As soon as the Manassas Gap Railway is in running order, intrench a brigade of infantry, say four regiments, with two batteries, at or near the point where that rail-way crosses the Shenandoah. Something like two regiments of cavalry should be left in that vicinity to occupy Winchester and thoroughly scour the country south of the railway and up the Shenandoah Valley, as well as through Chester Gap, which might perhaps be advantageously occupied by a detachment of infantry, well intrenched.

Block-house should be built at all the railway bridges.

Occupy by grand guards Warrenton Junction or Warrenton itself, and also some still more advanced point on the Orange and Alexandria Railway as soon as the railway bridges are repaired.

Great activity should be observed by the cavalry. Beside the two regiments at Manassas, another regiment of cavalry will be at your disposal to scout toward the Occoquan, and probably a fourth toward Leesburg.

To recapitulate: The most important points which should engage your attention are as follows:

1st. A strong force well intrenched in the vicinity of Manassas, perhaps even Centreville, and another force (a brigade), also well intrenched, near Strasburg.

2nd. Block-houses at the railway bridges.

3rd. Constant employment of cavalry well to the front.

4th. Grand guards at Warrenton, and in advance as far as the Rappahannock, if possible.

5th. Great care to be exercised to obtain full and early information as to the enemy.

6th. The general object is to cover the line of the Potomac and Washington.

The foregoing is communicated by command of Major-General McClellan.

Very respectfully, your obedient servant,

S. WILLIAMS,

Assistant Adjutant-General.

D.

HEADQUARTERS ARMY OF THE POTOMAC,
Steamer Commodore, April 1, 1862.

Brigadier General LORENZO THOMAS,

Adjutant-General U. S. Army:

GENERAL: I have the request that you will lay the following communication before the honorable Secretary of War:

The approximate number and positions of the troops left near and in rear of the Potomac are about as follows: