OKOLONA, August 7, 1864.

Brigadier-General CHALMERS,

Oxford:

Have Mabry move up as near Abbeville as possible. Dispute the enemy's crossing the Tallahatchie, but if forced to fall back destroy the railroad as effectually as possible between Abbeville and Grenada. Have your forces up as near the enemy as possible. Will send you further orders on Wednesday morning. Press teams and negroes, if necessary, to haul up forage for your troops.

N. B. FORREST,

Major-General.

ABBEVILLE, August 7, 1864.

Brigadier-General CHALMERS,

Oxford:

The enemy succeeded in crossing this p. m. before I knew anything of their appearance. I will endeavor to check them to-night. Come down, if possible.

W. B. WADE,

Colonel, &c.

MOBILE, August 7, 1864.

(Via Augusta 8th.)

Honorable J. A. SEDDON,

Secretary of War:

Some veteran infantry needed here at once. Gaines is under attack by land and water. Powell was evacuated after sustaining a short bombardment. Morgan and Gaines seem resolved. No force on Lower Mississippi. Canby's force reported variously from 17,000 downward. Visible force stated at 4,000 on Dauphin Island. The force which advanced from La Grange estimated this morning at 7,000. Forrest telegraphs cheerfully. Engineer officer just reports damage to Gaines and Morgan sLight, and thinks their resistance will be stubborn.

DABNEY H. MAURY,

Major-General.

ENGINEER OFFICE,

Mobile, August 7, 1864.

Major General J. F. GILMER,

Chief of Engineer Bureau, Richmond, Va.:

Have been ordered to place iron-clad floating battery, which was being changed into a very strong two gun battery, in its present unfinished condition, at lower obstructions near Choctaw Spit. Position is very isolated. Completion of battery is rendered difficult, and even if completed it cannot hold out long by itself against an attack by the whole of the enemy's fleet. In my opinion our efforts should be concentrated on making the line from Redoubt Numbers 1 to Battery McIntosh as strong as possible, and on this line my limited force should be employed. Channel south of obstructed lower gap will be filled with torpedoes.

V. SHELIHA,

Lieutenant-Colonel and Chief Engineer.