CIRCULAR.] DEPT. OF THE WEST, Jackson, MISS., July 16, 1863.

The time having arrived when, in the opinion of the commanding general, the safety of this army renders necessary a retrograde movement the following order will be observed:

The right wing of the army, consisting of the DIVISION of Major-Generals Loring and Walker, with the batteries attached to them, will retire by the upper Brandon road, crossing the Pearl River on the upper bridge, at Carson's Ferry.

The left wing, composed of the DIVISIONS of Major-Generals Breckinridge and French, will retire by the old Brandon road, crossing Pearl River on the bridges near the lower end of the town.

The artillery in or near the trenches will be moved by had for at least half a mile to the rear, when they will be limbered up and moved without delay by the routes, above designated. The reserve artillery of Major [W. C.] Preston will remain for the present, and march with the DIVISIONS to which they are temporarily attached. The generals commanding DIVISIONS will have details made, 12 men for each piece, who, with the cannoneers, will drag them to the points where they are to be limbered up.

The artillery will be moved at 9 p. m., and every arrangement must be made previously to insure punctuality. Where the artillery crosses the railroad, the rails and sleepers must be taken up, except at the regular crossings. At 10 p. m., the whole of the infantry force, with the exception of the skirmishers and pickets in advance, will march out from the trenches rapidly and noiselessly by brigades, each brigade moving by its right flank.

The brigades of General Loring's DIVISION and General Walker's DIVISION will move by the most practicable routes to that part of the low ground east of the town, just below the ruins of the Bowman House. General Walker will here form his DIVISION, without halting, and proceed directly to the upper bridge, and thence toward Brandon. General Loring will from his DIVISION, and, as soon as General Walker has cleared the road, will proceed in the same direction.

To prevent confusion, General Walker will move along the street immediately south of the Bowman House and the next two streets north of it. General Loring will gain the low ground by any street or road north of those assigned to General Walker. General French's DIVISION will reach the bridges which he is directed to cross by the three streets immediately south of the State-house, and thence by the new road to the bridges. He will form his DIVISION while on the march. After crossing the river, General French will march toward Brandon by the old Brandon road.

General Breckinridge will form his DIVISION, on the march, on the first favorable ground, crossing the bridges, which he will reach by the nearest and most frequented route, after General French had crossed, and follow him. The wagons and batteries of both these DIVISIONS will cross only by the trestle-bridge. At 1 a. m., the whole line of skirmishers and pickets will be quickly drawn in, and will follow their respective DIVISIONS with as much celerity as possible.

Generals commanding DIVISIONS and brigades will see that their staff officers acquaint themselves thoroughly with the points and roads herein mentioned, that they may prevent confusion or delay.

By command of General Johnston:

BENJ. S. EWELL,

Assistant Adjutant-General.