WASHINGTON, D. C., August 28, 1862 - 7.40 p. m.

Major-General McCLELLAN, Alexandria, Va.:

There must be to further delay in moving Franklin's corps toward Manassas. They must go to-morrow morning, ready or not ready. If we delay too long to get ready there will be no necessity to go at all, for Pope will either be defeated or be victorious without our aid. If there is a want of wagons, the men must carry provisions with them until the wagons can come to their relief.

H. W. HALLECK,

General-in-Chief.

ALEXANDRIA, August 28, 1862 - 10 p. m.

(Received August 29, 12.20 a. m.)

Major-General HALLECK,

General-in-Chief U. S. Army:

Your dispatch received. Franklin's corps has been ordered to march at 6 o'clock to-morrow morning. Sumner has about 14,000 infantry, without cavalry or artillery, here. Cox's brigade of four regiments is here, with two batteries of artillery; men of two regiments, much fatigued, came to-day. Tyler's brigade of three new regiments, but little drilled, is also here. All these troops will be ordered to hold themselves ready to march to-morrow morning, and all, except Franklin's, to await further orders. If you wish any of them to move toward Manassas please inform me. Colonel Wagner, Second New York Volunteer Artillery, has just come in from the front. He reports strong infantry and cavalry force of rebels near Fairfax Court-House. Reports numerous, from various sources, that Lee and Stuart, with large forces, are at Manassas; that the enemy with 120,000 men, intend advancing on the forts near Arlington and Chain Bridge, with a view to attacking Washington and Baltimore. General Barnard telegraphs me to night that the length of line of fortifications on this side of the Potomac requires 2,000 additional battery men, and additional troops to defend intervals, according to circumstances. At all events, he ways an old regiment should be added to the force at Chain Bridge and a few regiments distributed along the lines, to give confidence to our new troops. I agree with him fully, and think our fortifications along the upper part of our line on this side of river very unsafe with their present garrisons, and the movements of the enemy seem to indicate an attack upon these works.

GEO. B. McCLELLAN,

Major-General.

WASHINGTON, August 28, 1862.

General GEORGE B. McCLELLAN, Alexandria:

In Fort Marcy is one platoon Fourth New York Artillery; near it one regiment of new troops. In Fort Ethan Allen, one company Fourth New York Artillery; near it the One hundred and twenty-seventh Pennsylvania (new regiment). In Fort Corcoran, one company and one platoon Fourth New York Artillery. In Forts DeKalb, Woodbury, Tillinghast, Craig, and Haggerty, and Barnard, one platoon Fourth New York Artillery each; and in Fort Albany two companies of same regiment. This regiment is about 600 strong, and is well used to the