HDQRS. CAVALRY CORPS, ARMY OF THE POTOMAC, Lee's Mill, Va., July 30, 1864-6 p. m.

Major-General HUMPHREYS,
Chief of Staff, Army of the Potomac:

GENERAL: I have the honor to report that I met the advance of Hampton's division (Sixth South Carolina, Butler's brigade) at Lee's Mill. The regiment (Sixth South Carolina), has been driven beyond the mill. Prisoners captured report Fitz. Lee's and Hampton's cavalry divisions camped at Reams' Station.

Very respectfully,

D. McM. GREGG,

Brigadier-General of Volunteers.

P. S.-My headquarters for the night will be at Lee's, near Lee's Mill.

HDQRS. CAVALRY CORPS, ARMY OF THE POTOMAC, Lee's Mill, July 30, 1864-8.40 p. m.

Major-General HUMPHREYS,
Chief of Staff:

GENERAL: I have the honor to inclose you copy of the order establishing cavalry picket-line, which requires no explanation.

Very respectfully,

D. McM. GREGG,

Brigadier-General, Commanding.

[Inclosure.]

ORDERS.] HDQRS. CAV. CORPS, ARMY OF THE POTOMAC,

July 30, 1864.

In compliance with instructions from the headquarters Army of the Potomac, the Third Cavalry Division will maintain the picket-line as at present established. The First Cavalry Division will take post near Lee's Mill with its picket-line connecting on the right with the left of the Third Division on the Jerusalem plank road, the left of its picket-line resting on the Norfolk railroad at the point where the road from Lee's Mill to Prince George Court-House crosses it. One brigade of the Second Cavalry Division will be posted on the Norfolk railroad at the above-named intersection, and will picket to Mount Sinai Church. The remaining brigade of the Second Division will be posted at Prince George Court-House, continuing the picket-line from Mount Sinai Church to the James River. Any attack made by the enemy on any of the roads crossed by the picket-line as above defined will be strongly resisted and immediately reported to these headquarters. Corps headquarters will be at McCann's, on the Norfolk railroad. The foregoing dispositions will be carried into effect at once.

By command of Brigadier-General Gregg:

JAS. W. FORSYTH,

Lieutenant-Colonel and Chief of Staff.

HEADQUARTERS ARMY OF THE POTOMAC, July 30, 1864-6.30 a. m.

Brigadier-General WILSON,

Commanding Third Division Cavalry:

Burnside's mine has been exploded, and we have the enemy's line in Burnside's front, and Burnside's troops are moving up to the crest be-