HEADQUARTERS ARMY OF THE POTOMAC.

September 11, 1862-1.15 p. m.

Gov. ANDREW G. CURTIN, Harrisburg, Pa.:

I am in hourly expectation of gaining definite new from Ridgevillle and New Market. I thought to-day to know definitely whether the enemy are still massed near Frederick; whether they have any force east of the Monocacy; whether they have moved on Hagerstown in large force. I now think nearly all their available forces is on this side of the Potomac.

I would urge upon Your Excellency, in the event of their moving upon Pennsylvania, to take sure means to delay their advance by destroying bridges, obstructing the roads, harassing their front, flank, and rear, destroying supplies, &c. This in necessary to enable me to gain time to take the best route to foil their purpose.

GEO. B. McCLELLAN,
Major-General, Commanding.

McCain is at Harrisburg.

HARRISBURG, September 11, 1862.

(Received 8 p. m.)

Major-General McCLELLAN, Rockville:

We have advices that enemy broke up whole encampment at Frederick yesterday morning, 3 o'clock, and marched in direction of Hagerstown, with over three hundred pieces artillery, large bodies of infantry and cavalry, Stonewall Jackson leading. Jackson in now in Hagerstown. Man who gives information said rebel army marching 5 a. m. to 9 p. m. yesterday out of their camps at Frederick. Men all believed they were going to Pennsylvania. We shall need a large portion of your column in this valley to save us from utter destruction.

A. G. CURTIN,

Governor.

HEADQUARTERS ARMY OF THE POTOMAC,
Middlebrook, Md., September 11, 1862-11 p. m.

(Received 4 a. m., September 12)

His Excellency ANDREW G. CURTIN, Harrisburg:

You dispatch just received. I have ordered General Reynolds to report to you at the earliest practicable moment. This army in not sufficiently strong to divide it, but I rely upon your troops to hold the enemy in check until I can overtake him.

GEO. B. McCLELLAN,

Major-General, Commanding.

BALTIMORE, MD.,

September 11, 1862-10 p. m.

Major-General McCLELLAN, Rockville:

I have just received, on my return from Washington, your telegram of this date. The Monocacy Bridge is reported to be totally destroyed, and the masonry of the piers and abutments largely damaged. We have timber and all necessary material at Harper's Ferry. If this can be obtained, and our bridge men from that vicinity, with supplies we can command here, our engineer states that by most energetic efforts