MARTINSBURG, July 12, 1864.

(Received 6. 07 p. m.)

[General HUNTER:]

A dispatch from Hagerstown says the enemy are falling back this way, having been foiled in their attempt to cross the Potomac. This cannot be true. I will join Howe to-morrow. Can you give me any information as to the number of Crook's regiments that I may expect to be near there by to-morrow evening? I would like to take with me one or two of his regiments.

J. C. SULLIVAN,

Brigadier-General.

CUMBERLAND, July 12, 1864.

Brigadier General J. C. SULLIVAN,

Martinsburg:

Please ascertain if the reported falling back is probably true. If so, you will remain with your force to repel any attack of enemy to cross at upper fords. If, however, you decide, after acquiring necessary information, to proceed to join Howe, you will leave behind the regiments belonging to General Crook, as it is deemed unadvisable to send any of them farther at this time than Martinsburg.

D. HUNTER,

Major-General.

CUMBERLAND, July 12, 1864-9 a. m.

Brigadier-General SULLIVAN,

Martinsburg:

The Wheeling papers report that General Tyler and about 1,000 of our men were captured at Monocacy bridge on Saturday. They possibly may be sent to the rear via Martinsburg or Kearneysville. Look out for them; recapture them if they come within your reach. The enemy are threatening Baltimore.

B. F. KELLEY,

Brigadier-General.

CUMBERLAND, July 12, 1864-10 a. m.

Brigadier-General SULLIVAN,

Martinsburg:

Keep yourself fully advised of all movements on the Shepherdstown pike through Kearnesville to Winchester, and vice versa. Would it not be well to occupy Kearneysville?

B. F. KELLEY,

Brigadier-General.

BALTIMORE, July 12, 1864.

(Received 13th.)

General GRANT:

GENERAL: Railroad bridge at Gunpowder only slightly damaged; can be repaired in three days. Rebel cavalry between Beltsville and Laurel have torn up the railroad. Guard at Laurel and Annapolis Junction have fallen back-the latter to Annapolis, by