Thomas, and to draw back the trains of the corps, under an escort of one division, to near the crest of the mountain in front of Winston's, holding it in readiness either to move forward to La Fayette or Stevens' Gap, or to be withdrawn into Lookout Valley. Three detached brigadiers will be left instead of an entire division-your brigade, from Third Division; Dodge's, from Second Division, and Post's brigade, from First Division. The latter is now located near Winston's, with its trains, &c. You will have command of the three brigades, and have charge of the baggage and supply wagons of the entire corps, except the few wagons necessary to take forward the three days' rations for the troops.

One-third of the division ammunition train will be left with you. Post already has his portion of the First Division train. Some of the trains under your charge are now on Lookout Mountain and some are in the valley. It will be necessary for you to have them collected and parked at Little River, on the mountain, about 3 miles of Winston's, and to place your command in the best place to protect them. Post's command and trains can be left at Winston's, unless it should become safer to draw it nearer the others. It will be difficult to support your animals with forage on the mountain. Some can be found there; the rest will have to be hauled up from the valley. Empty supply trains will be sent to Stevenson for rations with suitable guards. The trains of the several divisions will be sent together when practicable. You will have the supervision of the trains of the corps going and returning from the depot for supplies. It is reported that one or two small detachments of rebel cavalry have been sent around to try and capture our trains. Colonel Post will inform you of the situation of affairs in the neigh-boyhood of Winston's. There are two roads over Little River to Winston's. We move from here by the road on the east side of Lookout Mountain to Dougherty's Gap, at the head of McLemore's Cove; expect to reach there to-night. General Stanley's command is here. It will cover our movement and your position. General Stanley is to leave you a detachment of cavalry. We will communicate with you frequently. Let us hear from you from time to time. General McCook wishes you to keep a good lookout down Will's Valley, and to be as vigilant as possible. This, general, will be your letter of instructions until further orders.

Very respectfully, your obedient servant,

G. P. THRUSTON,

Assistant Adjutant-General and Chief of Staff.

NEAR ALPINE, September 13, 1863-8 a.m.

Colonel HARRISON:

You will proceed with your regiment, with the exception of the two companies sent up the valley, and try and reach General Thomas by the most direct route on the Lookout Mountain. He must be at or near Steven's Gap, which enters the mountain near Easley's, and I think about 5 miles this side of Trenton. He wishes you to see him, and say to him that General McCook is marching on Dougherty's Gap of McLemore's Cove, and that if he (General T.) wishes him to take any other direction than that, General McCook wishes to be informed of it at once. General McCook is ordered by General