WASHINGTON, September 8, 1862-8.42 p. m.

Major-General McCLELLAN, Rockville:

Nothing from Colonel Miles or elsewhere about position of enemy since I telegraphed this morning.

H. W. HALLECK,

General-in-Chief.

CAMP NEAR ROCKVILLE, MD.,

September 8, 1862-8 p. m. (Received 9.40 p. m.)

Major General H. W. HALLECK,

General-in-Chief:

Nothing new to report, except that I have heard from the cavalry at Mechanicsville, who report railroad destroyed by rebels from Monrovia to the Monacacy, and that a force of about 7,000 men reached Frederick yesterday, they being a part of Jackson's force. The cavalry skirmishes to day near the Monocacy were quite successful, so far as heard from. I have ordered reconnaissances in all directions to-morrow, including one well to the north and northwest. I think that we are now in position to prevent any attack in force on Baltimore, while we cover Washington on this side. I am rather weak in cavalry on the right, but am hourly expecting more of Averell's brigade. We are prepared to attack anything that crosses the Potomac this side of the Monocacy. I am by no means satisfied yet that the enemy has crossed the river in any large force. Our information is still entirely too indefinite to justify definite action. I am ready to push in any direction, and hope very soon to have the supplies and transportation so regulated that we can safely move farther from Washington, and clear Maryland of the rebels. The time occupied in ascertaining their position, strength, and intentions will enable me to place the army in fair condition. I do not feel sure that there is no force in front of Washington. I think I can now answer for it that they shall not cross the river this side of Monocacy, and that they shall not take Baltimore without defeating this army. I am also in position to hasten to the assistance of Washington, if necessary. As soon as I find out where to strike, I will be after them without an hour's delay.

GEO. B. McCLELLAN,

Major-General.

HEADQUARTERS,
Rockville, Md., September 8, 1862-10 p. m.

Major-General HALLECK,

General-in-Chief:

After full consideration, I have determined to advance the whole force to-morrow; the right wing to Goshen and Cracklinton, holding guard over bridges and other advance points by strong advance guard; the cavalry well out on the right and front; the center near Middlebrook; Franklin to Darnestown, holding the line of the guards by advance guards; Couch to guard, leaving a brigade at Offutt's Cross-Roads; and Sykes' division will move to-morrow, according to the information I receive, probably toward Gaithersburg, but wherever the latest information may show the enemy to be in greatest force.

GEO. B. McCLELLAN,

Major-General.