CHAMBERSBURG, July 29, 1864.

Brigadier-General AVERELL:

Some men in from Mercersburg say positively that about 6 p. m. two columns of rebels entered Mercersburg, and drove out our forces. They had two pieces of artillery with them. I think this reliable. McLean was trying to check them.

D. N. COUCH,

Major-General.

CHAMBERSBURG, July 29, 1864-10. 15 p. m.

Brigadier General W. W. AVERELL:

Lieutenant McLean was driven out of Mercersburg by about 200 of the enemy. A force of about 500 and two pieces of artillery afterward came up.

D. N. COUCH,

Major-General.

CITY POINT, VA., July 30, 1864-1 p. m.

(Received 7 a. m. 31st.)

Major-General HALLECK,

Washington, D. C.:

I have ordered a division of cavalry to proceed immediately to Washington.

U. S. GRANT,

Lieutenant-General.

CITY POINT, VA., July 30, 1864.

Major-General MEADE,

Commanding, &c.:

It is almost certain that none of the enemy's force recrossed the James until since 2 p. m. to-day, and but two or three regiments then. It is nearly as much of an object to draw them back to this as it is to cut the road, that I want the expedition to go out. I am very much afraid Lee will send an army corps to re-enforce Early, who, I understand from a dispatch of last night, had driven Averell out of Hagerstown toward Greencastle. Since writing the above I have information from signal station on the James that the enemy are now crossing in a continuous stream. You may, therefore, suspend the order for movement down the railroad. We may get an attack from the enemy to-morrow evening or next day morning, and want to be prepared for it.

U. S. GRANT,

Lieutenant-General.

CITY POINT, VA., July 30, 1864.

Major-General MEADE,

Commanding, &c.:

The enemy have commenced crossing the Potomac at the different fords above Harper's Ferry. Unless re-enforcements are sent from Lee's army, I think we have the greatest abundance of infantry and