HEADQUARTERS DEFENSES OF WASHINGTON,
September 10, 1862-11 a. m.

Major General GEORGE B. McCLELLAN,

Rockville, Md.:

Your dispatch of last night received this morning. The order placing General Heintzelman in command of all troops for the defense of Washington south of the Potomac, under my general orders, came from the President yesterday afternoon, through the General-in-Chief. I knew nothing of it until I received General Halleck's order. Under these circumstances I do not feel at liberty to suspend the order. It was carried into execution before receiving your dispatch. I beg to assure you that I should have made, and will make, no important change in your arrangements without your concurrence.

N. P. BANKS,

Major-General.

WASHINGTON, September 10, 1862-8.30 p. m.

General MARCY,

Chief of Staff, &c., Rockville, Md.:

My reference was to the Catoctin Mountains. It seemed as if a strong force lay between Leesburg and the Catoctin. It is thought here, tonight, that a heavy force has crossed the river, and is in the rear of the Monocacy. It is not impossible that the mean to hold Northern Virginia, in this way threatening Washington, Baltimore, Pennsylvania, and Ohio at the same moment.

Please forward us the news.

N. P. BANKS,

Major-General.

HEADQUARTERS ARMY OF THE POTOMAC,
September 10, 1862-10 p. m.

Major General N. P. BANKS:

Our pickets extend up to the mouth of the Monocacy. No force of the rebels has crossed this side of there within the past thirty-six hours. A force of 5,000 of the enemy is reported as having been to-day at a point 3 miles beyond the Monocacy. The enemy is believed to be in heavy force in the neighborhood of Frederick.

R. B. MARCY,

Chief of Staff.

WASHINGTON, September 10, 1862.

Major-General BANKS, Commanding, &c.:

GENERAL: It is very important that General Slough should have adequate force at his command at Alexandria. I hope his forces will not be taken away, unless there is absolute necessity for it. He can open a school of instruction for his regiments, in addition to their police duty.

Very respectfully,

H. W. HALLECK,

General-in-Chief.