HEADQUARTERS,
Richmond, Va., April 3, 1862.

General J. B. MAGRUDER,

Commanding Army of the Peninsula, Yorktown, Va.:

GENERAL: The general commanding directs me to acknowledge the receipt of your letter of the 29th ultimo in reference to the smallness of your cavalry arm and the necessity of having it increased, and requesting to have Lieutenant-Colonel Ball, of the Virginia cavalry, ordered to report to you. Lieutenant-Colonel Ball has been ordered accordingly, and it is supposed had reported to you already.

Five companies of cavalry, belonging to the Wise Legion, have also been ordered to report to you. Two of them left this morning, and the other three will start to-morrow. This command, with the exception of two companies (Shield's and Caskie's), are tolerably well armed, equipped, and mounted, and it is hoped you can supply the deficiencies in these two.

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

T. A. WASHINGTON,

Major and Assistant Adjutant-General.

FREDERICKSBURG, April 4, 1862.

General R. E. LEE:

GENERAL: I attempted last night to give the President by telegraph the information I found here, but the operator reported that he was unable to communicate with Richmond, the office there being closed apparently.

General Sumner's headquarters are at the Warrenton Junction. The force of the enemy between that point and Alexandria is 40,000 or 50,000. He is rebuilding the railroad bridges. This is reported by prisoners taken by scouting parties.

A party, estimated at 2,500, marched yesterday from the neighborhood of the Chopawampsic to Stafford Court-House, driving in our pickets. It retired during the night.

General Longstreet wrote on the 2nd that General Jackson reported the enemy advancing in force and at Woodstock at 2.30 p.m. on the 1st instant. Yesterday afternoon he wrote that General Jackson reported the enemy on the 2nd advancing to his left. He asks for re-enforcements to give battle. General Longstreet replies that it is necessary that he should come nearer to our position to make that practicable. I have told him (General Longstreet) that two days' march is the utmost distance to which it would be prudent to detach. Two brigades are held in readiness to march. General Jackson has been instructed if the enemy continues to press him to leave the valley by the Swift Run Gap and move toward Orange Court-House. Sumner's position is as near this place as Rapidan Bridge.

General Longstreet reported at 3 p.m. yesterday that General Early's brigade would get off during the day (to Richmond) and General Griffith's brigade to-day. I directed him, upon the information found here, to stop the movement. Early's troops will probably arrive in Richmond before this reaches you.

You will perceive that the loss of that division will make us too weak to hold this line if pressed in front and on the left flank at the same time. The President, however, will always have the means of judging where those troops are most needed.