HEADQUARTERS EIGHTH ARMY CORPS, Baltimore, June 28, 1863.

Commodore T. A. DORNIN,
Commanding Naval Station, Baltimore:

COMMODORE: Among the United States steamers now in this port for repairs, there are, I understand, three or four, perhaps-the Philadelphia, the Daylight, and the Seymour-[that] are afloat, and in condition for service. I deem it exceedingly important that these available gunboats should be placed in position to bear upon this city and some of the approaches to it witch their fire, as far as practicable, in case of an emergency that may occur. The points in the stream which I would indicate for such commanding positions are, particularly, the foot of Broadway, in the harbor proper (Northwest Branch), opposite Locust Point, and in the Middle Branch up as near as possible to the Long Bridge, covering the west side of the city. If you can make this disposition of these vessels, I trust no time will be lost in doing it.

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

ROBT. C. SCHENCK,

Major-General, Commanding.

WASHINGTON, D. C., June 28, 1863.

Major-General HEINTZELMAN,

Commanding, &c.:

GENERAL: You will assume command of all the dismounted cavalry in this department belonging to the Army of the Potomac, have them mounted as soon as possible, and use them until further orders. Very respectfully, your obedient servant,

H. W. HALLECK,

General-in-Chief.

P. S. -Also take command of all the cavalry in the District.

WITHIN TWO MILES OF CARLISLE, June 28, 1863-6. 15 a. m.

Captain RENO,

Chief of Staff:

In accordance to orders, I have advanced as far as the enemy's pickets, and have taken 1 prisoner. General Rodes' division is in your immediate front. General Ewell did not go to Carlisle as yet; they seem to count every step of the road. If I am hard pushed, I will fall back, and send you another dispatch. The morning is very foggy, and I have great difficulty in discovering the enemy. They say they will be in Harrisburg to-morrow. Send me word what to do if [sic] I will fall back immediately and keep sight of the enemy. I will await your answer. Their column is composed of cavalry and infantry.

JOHN McDONALD,

Commanding Pickets.