RICHMOND, VA., September 21, 1863.

General R. E. LEE,

Commanding Army of Northern Virginia:

GENERAL: Yours of the 20th has been received. I concur with you in your estimate of the movement from Norfolk, but even thus regarded, it seems difficult to make the needful provision against it. The division sent here was numerically not equal to the two brigades taken away, and the necessities of General S. Jones caused the brigade of General Corse to be sent to him. I directed the Adjutant-General, in furtherance of your wish, to send another of Pickett's brigades to relieve General Cooke's, so that you might draw that to you.

Since I commenced writing, a dispatch from General Bragg has arrived from Chickamauga River, September 21. He says:

After two days' hard fighting we have driven the enemy, after a desperate resistance, from several positions, and now hold the field, but he still confronts us. The losses are heavy on both sides, especially so in our officers. We have taken over 20 pieces of artillery and some 2,500 prisoners.

Have this moment received the following dispatch from the adjutant-general of General S. Jones, from Dublin, September 21:

Courier from General Jones arrived at Bristol yesterday. He was at Zollicoffer. Enemy moved on that point yesterday at 8 o'clock. Skirmished with our forces. Moved off in the direction of Blountsville and Jonesborough. Colonel Carter started after then with cavalry and artillery last night.

These dispatches indicate that the attention of the enemy will be concentrated on General Bragg, and that General Jones will thereby be relieved for the present. I have been, since you left, anxious to go to the Army of Tennessee, but have been delayed by causes which you readily understand. Unless we receive more decisive intelligence than that herein communicated, it is still my purpose to go as soon as other duties will permit. If we can obtain a complete victory in that quarter, and drive the enemy, broken and discouraged, from the present field of operations, the forces you sent can most readily return to you through East Tennessee adn Southwestern Virginia, and I trust it may be practicable then to bring them to you before the enemy shall render their presence with you a necessity. In the meantime, I have urged that the greatest efforts should be made to procure and send recruits to you, and I hope the Legislature, now in session here, will adopt such action as will bring out the arms-bearing population who are not subject to enrollment for the Confederate Army, and thus afford to you an auxiliary force, which will relieve you from the necessity of detaching troops to guard localities and lines of communication.

I have not been able to avoid vain regrets at the detachment of troops by the southern route, which, if the course of General Bragg could have been foreseen, would have been more valuable in East Tennessee, whence they could have been more readily withdrawn to support you in time of need. If, however, General Bragg's operations should be successful, and rapidly followed up, it may prove that the course adopted was, after all, the best.

Only one battalion of artillery (Alexander's) has gone beyond Petersburg, and I have directed that no horses should be sent. The supply at Atlanta, if correctly reported, will suffice for that battalion, but no more,and you will no doubt require all the artillery horses which General Longstreet had.