HEADQUARTERS THIRD CAVALRY BRIGADE, Camp near Newburn Bridge, Va., May 12, 1864.

Colonel W. H. POWELL,
Commanding Second Virginia Cavalry:

SIR: You will immediately proceed with your regiment as rapidly as possible to Blacksburg. If, on arriving there, you find General Crook has left there, you will take a good position on the Christiansburg road,so as to command that road against the approach of an enemy from that direction. It is important that you arrive there before the enemy.

By command of Brigadier-General Duffie:

E. W. CLARK, JR.,

Assistant Adjutant-General.

CUMBERLAND, MD., May 12, 1864-10. a. m. (Received 12.20 p. m.)

Major General H. W. HALLECK,

Chief of Staff:

All quiet and safe this a. m. Trains running as usual. I think Rosser has fallen back, though, I have no cavalry to make a reconnaissance. Three regiments of the Ohio militia have arrived; two are here, and one at New Creek. A brigade of General Terry's division has just passed east, bound for Washington.

B. F. KELLEY,

Brigadier-General.

CUMBERLAND, May 12, 1864-10 a. m. (Via Martinsburg.)

Major-General SIGEL:

We are all quiet this a. m. I think Rosser's and Imboden's forces have fallen back, though I have no cavalry force to make a reconnaissance. Colonel Higgins arrived here last night; his command badly broken down. I have supplied him with ammunition, rations, and forage, and have ordered Captain Harrison, assistant quartermaster, to put his force of blacksmiths to work shoeing his horses. The One hundred and thirty-fourth and One hundred and sixteenth Ohio Militia have arrived here, and one regiment at New Creek. The road and telegraph are yet safe and working.

B. F. KELLEY,

Brigadier-General.

CUMBERLAND, MD., May 12, 1864-4 p. m.

Major General F. SIGEL:

Colonel Wilkinson reports that his scouts have returned, and report the enemy as having fallen back, probably by the same route they came-say Brock's Gap and the Lost River Valley. I now think the force was Colonels Imboden, McNeill, and Harness. With the militia now arriving and some effective cavalry I can protect the road and your supplies.

B. F. KELLEY,

Brigadier-General.

(Copy to Halleck.)