HEADQUARTERS DEPARTMENT OF THE CUMBERLAND, Trenton, Ga., September 9, 1863-9.30 a.m.

Major-General STANLEY,
Chief of Cavalry:

A dispatch from General Wagner of 8.30 p.m. yesterday was received this morning, stating that the rebels evacuated Chattanooga yesterday, and he would occupy it this morning. One of our scouts reports that the mass of the rebel force was yesterday at the northern spur of Missionary Ridge, 6 miles from Chattanooga. A vigorous pursuit has been ordered by the whole army. General Crittenden is moving into Chattanooga this morning to commence the pursuit. General Thomas moves on La Fayette, and General McCook has been ordered to move an Alpine and Summerville with his whole force. The general commanding has strong hopes that we may be able to inflict very serious injury upon the rebel army.

In view of the uncertainty of the enemy's route the general commanding leaves your operations to your own discretion, with the general direction to cover our extreme right flank and move upon Rome or such other point as shall do the enemy most serious harm. If their retreat can once be turned into a rout, your command can do them immense injury. General McCook has been directed to see to the protection and forwarding of your train in case you have left no arrangement to that effect. Minty is ordered to cross at Chattanooga and will accompany General Crittenden in the pursuit and will join you in a few days.

Very respectfully, your obedient servant,

J. A. GARFIELD,

Brigadier-General and Chief of Staff.

HEADQUARTERS CHIEF OF CAVALRY, Henderson's, September 9, 1863.

Colonel E. M. McCOOK,
Commanding First Division Cavalry:

COLONEL: The general commanding directs that you have reveille at 3.30 a.m. to-morrow morning, and horses saddled and bridled, prepared for any movement. General Davis has arrived here and has a brigade at the top of the gap. I send you two orderlies who will stay with you to-night, and if you have any communications to send send by them, as they will know the road and carry the communications promptly.

Respectfully,yours,

WM. H. SINCLAIR,

Assistant Adjutant-General.

HDQRS. FIRST BRIGADE, SECOND CAVALRY DIVISION, Sale Creek Camp Ground, September 9, 1863.

Lieutenant-Colonel GODDARD,

Asst. Adjt. General, Department of the Cumberland:

SIR: I sent a small scout across the river at the mouth of Sale Creek yesterday. They patrolled the country 3 or 4 miles up and down the river, but could not discover any trace of the enemy. I