WASHINGTON, July 6, 1864 - 2 p. m.

(Received 7th.)

Lieutenant-Colonel GRANT,

City Point, Va.:

General Howe has reached Harper's Ferry with his command. Sigel is expecting an attack to-day. Most of Hunter's forces have reached Parkersburg, and are coming forward. It is believed that Ewell's corp's, under Early, is in the Valley. It is reported that Sigel abandoned a large amount of public stores at Martinsburg, without making any defense. As that place was without fortifications, and only a mere outpost, it is difficult to understand why the stores were taken from the depot at Harper's Ferry. General Hunter says that Sigel had sufficient forces to defend the railroad, if he had used them properly.

H. E. HALLECK,

Major-General and Chief of Staff.

CITY POINT, VA., July 6, 1864 - 3 p. m.

(Received 7th.)

Major-General HALLECK,

Washington, D. C.:

A part of the force directed by me to go north is already off, and the whole of it will be in the course of an hour or two. It will probably be as well to let it go now, and return it as soon as you deem it perfectly safe to do so. I think there is no doubt but Early's corps is near the Baltimore and Ohio road, and if it can be caught and broken up it will be highly desirable to do so. It is important to our success here that another raid should be made up the Shenandoah Valley, and stores destroyed and communications broken.

U. S. GRANT,

Lieutenant-General.

WASHINGTON, July 6, 1864 - 5 p. m.

(Received 7th.)

Lieutenant-General GRANT,

City Point, VA.:

Please give me an estimate of the number of dismounted cavalry sent, in order that I may provide remounts. They should bring their equipments with them. It appears that General Sigel had no scouts out to give notice of the enemy's approach, and he seems to guess at their numbers, estimating them from 7,000 to over 30,000. Other estimates are from 20,000 to 30,000. I think there is no further doubt about Ewell's corps. Probably, also, Breckinridge's, Imboden's, Jackson's, and Mosby's commands. If so, the invasion is of a pretty formidable character. I have hurried General Hunter forward, but get no reply from him. I fear that the railroad is so much injured that his advance will be slow. Can you send a good major-general to command in the field till Hunter arrives? I think General Augur should not leave Washington.

H. W. HALLECK,

Major-General and Chief of Staff.