Major General WILLIAM T. SHERMAN, Comdg. Fifteenth Army Corps:

Washburn, who is in command at Haynes' Bluff, reports that a DIVISION of rebel cavalry is encamped 2 miles beyond Mechanicsburg, and [W. H. T.] Walker, with an infantry force, is at Yazoo City. General W. S. Smith's DIVISION, from WEST Tennessee, is beginning to arrive, and, I suppose, will all be here to-day. This force goes to Haynes' Bluff, and will make a force of from 13,000 to 14,000 at that place. I have also received information that two brigades from Missouri are on their way, and have passed Memphis, and 8,000 are coming from Burnside's department. These latter I propose to land at Young's Point, and send across to Warrenton to close up the south side of Vicksburg. With the cavalry we have at Haynes' Bluff, when required, two brigades from your corps, and three from McPherson's, to be further relieved if it should become absolutely necessary, by taking all the troops to the left of McClernand [sic]. In case this has to be done, you will be detached temporarily from the command of your corps here, to take command at Haynes' Bluff whilst it may be besieged.

The order then intended to be conveyed is, that two brigades from the Fifteenth Army Corps be held in readiness to march to Haynes' Bluff at the shortest notice.

U. S. GRANT.

Colonel John A. RAWLINS,

Assistant Adjutant-General, Department of the Tennessee:

SIR: I have the honor to acknowledge receipt of General Grant's letter of this date, and to answer that I will be prepared to move, on the shortest notice, to Haynes' Bluff. I will make immediate orders to place Blair's brigades to the front, and draw back Tuttle's two brigades, to be ready to move to Haynes' Bluff, viz., Buckland's and J. J. Woods'.

One of Buckland's regiments (Judy's) is not on picket at Templeton's a point common to both Haynes' and this place. The other brigade has but three regiments, and Colonel Gresham, commanding a regiment of Indiana troops, in Johnson's brigade, of Lauman's DIVISION, has just been here, and is very anxious to come to my corps. He is one of my Kentucky colonels, and, if he could be transferred to me, I could give him command of a brigade. I told him General Lauman should consent before a written application should be made. He has gone to procure it. If this transfer could be made, it would complete an imperfect brigade, and would give Tuttle twelve regiments, four of which are now absent with Mower. I would like also to get another battery for this DIVISION, which now has only two four gun batteries, and, I am informed, Lauman has six batteries, two to each brigade. I have only three batteries to two of my DIVISIONS, and two for Tuttle.

Supposing, of course, that provisions are delivered at Snyder's by boat, and that rifle-pits are in course of construction, I take it the force indicated by the general will be ample for all contingencies. I would like to reconnoiter the ground from Milldale to the Bald Ground before an enemy makes his appearance from the direction of Yazoo City, on the ridge back of Haynes', and therefore will be prepared for further orders at once.

I am, &c.,

W. T. SHERMAN.