11. 30 A. M.

[P. S.]-A deserter has just been brought within our lines who reports the enemy's army all between Hagerstown and Williamsport; that they have brought up a bridge from Winchester, which is now thrown across at Williamsport; that they are using this bridge, not to cross their forces, but to bring over supplies; that the men are in fine spirits, and the talk among them is they must try it again. This deserter says he belongs to the artillery of Stuart's command. I send the information for what it is worth.

[Inclosure.]

HDQRS. LIGHT DIV., ARMY OF THE POTOMAC, July 9, 1863.

General S. WILLIAMS:

SIR: Baldy [W. F.] Smith is here with his command. Colonel [J. I.]

Gregg, with brigade of cavalry, who leaves for Boonsborough to-night, will send this. A scout brings information that Lee has one corps intrenched on the Williamsport pike from Hagerstown; another on Boonsborough pike; and Early is said to be up toward Middleburg (quien sabe?), between Newcastle [Greencastle?] and Hagerstown. The news of the capture of Vicksburg is confirmed. Have sent a cavalry reconnaissance toward Hagerstown this morning; it has not returned. Since writing the above, have felt the enemy's pickets with a regiment of cavalry at a bridge 4 or 5 miles from Hagerstown. They are stubborn. We drove them away, but they returned as we retired. General Smith is in with his mixed command. Am delighted to have the benefit of his counsel and advice. We are all right, but watch Early's division on my right toward Middleburg.

THOS. H. NEILL,
Brigadier-General, Commanding.

HEADQUARTERS ARMY OF THE POTOMAC,

July 9, 1863-5. 20 p. m.

(Received 7. 10 p. m.)

Major General H. W. HALLECK,

General-in-Chief:

I transmit herewith a copy of instructions this moment sent to General Naglee at Harper's Ferry. Very respectfully,

GEO. G. MEADE,

Major-General.

[Inclosure.]

HEADQUARTERS ARMY OF THE POTOMAC,
July 9, 1863-5. 20 p. m.

Brigadier-General NAGLEE,

Commanding Harper's Ferry:

Organize the re-enforcements in brigades as fast as they arrive, and send them, through Rohrersville, to join the left of the army, seeing that they have haversacks and three days' rations. First secure a garrison of 3, 000 or 4, 000 men to garrison Maryland Heights against a coup de main.

A. A. HUMPHREYS,

Chief of Staff.