TAZEWELL, Tennessee, December 1, 1863-6 p.m. (Received 8.55 a.m., 2nd.)

Maj. General H. W. HALLECK,

General-in-Chief:

The report of scouts sent out from the advance cavalry posts indicate that General Longstreet has commenced to retreat from his position around Knoxville. A large force of cavalry is now advancing on Maynardville, which I think is the flanking column of main body of Longstreet or Jones - the main body probably moving off on the Rutledge road. If this proves to be correct, I shall harass his flanks and rear as much as possible.

J. G. FOSTER,

Major-General.

(Same to Grant.)

TAZEWELL, Tennessee, December 1, 1863-8.30 p.m. (Received 9 a.m., 2nd.)

Maj. General H. W. HALLECK,

General-in-Chief:

Your dispatch is received. Three messages have been sent through to General Burnside, communicating full information of the troops marching to his relief and enjoining him to hold out to the last extremity. Reports from the outposts this evening concur, establishing the probability that Longstreet is retreating from Knoxville toward Virginia. We will take up a position to-morrow from which his flank can be harassed, or in which we can defend ourselves to advantage in case we should be attacked.

J. G. FOSTER,

Major-General.

CHATTANOOGA, December 1, 1863-7 a.m.

Major-General FOSTER:

Your dispatches of yesterday received.

Move as indicated in your first dispatch, or as may be modified by your own judgment.

U. S. GRANT,

Major-General.

CHATTANOOGA, December 1, 1863-9 p.m.

Maj. General J. G. FOSTER,

Tazewell, Tennessee:

Troops from here were crossing the Hiwassee yesterday. They may be looked for confidently on the 5th, and I think the 4th at Knoxville. Be prepared to give the best support you can.

U. S. GRANT,

Major-General.