CITY POINT, VA., July 16, 1864-4. 40 p. m. (Received 17th.)

Major-General HALLECK,

Washington, D. C.:

There can be no use in Wright following the enemy with the latter a day ahead, after he has passed entirely beyond (south of) all our communications. I want, if possible, to get the Sixth and Nineteenth Corps here, to use them here before the enemy can get Early back. With Hunter in the Shenandoah Valley and always between the enemy and Washington, force enough can always be had to check the invasion until re-enforcements can go from here. This does not prevent Hunter from following the enemy to Gordonsville and Charlottesville, if he can do it with his own force and such other improvised troops as he can get; but he should be cautious not to allow himself squeezed out to one side, so as to make it necessary to fall back into Western Virginia to save his army. If he does have to fall back it should be in front of the enemy, and with his force always between the latter and the main crossings of the Potomac. I do not think there is now any further danger of an attempt to invade Maryland. The position of the enemy in the West and here is such as to demand all the force they can get together to save vital points to them. The last attempt brought to the field so many troops that they cannot conceive the possibility of succeeding in capturing any important point, with a force of 30,000 or even 50,000 men, whilst the main Union army is within thirty hours of the capital. As soon as the rebel army is known to have passed Hunter's forces, recall Wright and send him back here with all dispatch, and also send the Nineteenth Corps. If the enemy have any notion of returning, the fact will be developed before Wright can start back.

U. S. GRANT,

Lieutenant-General.

HEADQUARTERS U. S. FORCES,
Poolesville, Md., July 16, 1864-7 a. m.

Major General H. W. HALLECK,

Chief of Staff, &c.:

GENERAL: Your dispatch of yesterday, by Captain Farrar, of my staff, was received toward evening, and about the same time I received intelligence through my own couriers from General Hunter's command, and also a dispatch from General Howe, at Harper's Ferry, where General Hunter had just arrived. A little later I received the dispatch of Colonel Chipman, of General Hunter's staff, to the Secretary of War, from which and from other information I learned that General Sullivan, with some 7,000 infantry and 2,000 cavalry crossed the Potomac at Knoxville, near Berlin, and was moving on Leesburg via Hillsborough. Fearing that he might meet the enemy in too strong force for his command, I have put the force here in motion for Leesburg, crossing at White's Ford, and have instructed General Ord to move as rapidly as practicable to the same point, crossing at Young's Island, about one and a half miles below Edwards Ferry.

The troops of the Nineteenth Corps reached this point late in the afternoon of yesterday, and constitute, with the two division of