vanced as a corps of observation, and that, if menaced by superior force of the enemy, you are to fall back to the lines of defense. General Heintzelman will be ready to send forward a portion of his troops to support this movement, should it become necessary. Telegraph such information as you may receive in duplicate to these headquarters.

Acknowledge.

RICH'D B. IRWIN,

Captain, Aide-de-Camp, and Actg. Asst. Adjt. General

(Copy sent to General Heintzelman, Arlington House, 12.30.)

HEADQUARTERS DEFENSES OF WASHINGTON,
October 13, 1862-10.30 p.m.

Brigadier General S. WILLIAMS

Asst. Adjt. General, Headquarters Army of the Potomac:

Telegram of 7 p.m. received 10.30. The troops last ordered to General McClellan are Stoneman's and Whipple's divisions. Stoneman has between 9,000 and 10,000, now at Poolesville, and ordered to report to you to-day. I sent you list this morning. Whipple has between 4,000 and 5,000, consisting of Piatt's and Carroll's brigades and Thirteenth New Hampshire Volunteers. General Halleck directed General Banks to keep Whipple's division until we can replace it in our front, which is now being done by a small division of new troops, under Abercrombie. When Whipple is relieved he will go by rail. Sent you list of Stoneman's division this morning. Will send list of Whipple's to-morrow.

Telegram about cooking stove will be attended to. Ruggles is ehre. Hammerstein hasn't gone yet; says he has been sick.

RICH'D B. IRWIN,

Captain, Aide-de-Camp, and Actg. Asst. Adjt. General

HDQRS. FORTIETH NEW YORK STATE VOLUNTEERS,
Near Conrad's Ferry, October 13, 1862.

Captain POTTER,

Acting Assistant Adjutant-General, Poolesville:

A scout, whom I sent over to-night, returned, and reports that large bodies of rebel cavalry are being concentrated at a place called Big Spring, the force which returned yesterday being met by re-enforcements there. This force is said to have come by the Leesburg road, the Waterford road, and Lovettsville, and is reported to be very large, say 7,000 cavalry and a large body of infantry. I respectfully suggest that a cavalry picket be stationed on Coleman's Island, and that a mounted orderly be detailed to my headquarters for the present in case of an emergency.

T. W. EGAN,

Colonel Fortieth New York.

POOLESVILLE, 11.30 p.m.-Forwarded by General Stoneman to General Banks, and copies sent by General Banks to Generals' McClellan, Heintzelman, and Sigel.