THE MANNER IN WHICH THE MOVEMENT IS TO BE MADE.

The acting chief of engineers will have caused, by 12 o'clock midnight of the 28th instant,a sufficient pontoon bridge, well covered to prevent noise, to be laid from the road on the south side of the James to a point near Varina or Aiken's Landing. The Eighteen Army Corps, with the exception of the colored division at Deep Bottom, will move across that bridge and make and attack upon the enemy's line in the manner hereinafter to be detailed. At the same time the Tenth Corps will cross the pontoon bridge at Deep Bottom and make in like manner and at the same time demonstration in connection with the Third Division of the Eighteenth Corps from that point.

THE POSITION AND NUMBERS OF THE ENEMY.

As near as can be ascertained, the enemy hold a line of earth-works starting at a point at or near Cox's Ferry,at station called by them Signal Hill, running thence easterly in the rear of Cox's overseer's house; from thence to a point in the rear of J. Aiken's house to the hill in rear of the point marked "New Market" on the map,across the Varina road, partially along the Kingsland road, which line, it is believed, terminates substantially as a continuous entrenched line at that point. Most of the line has abatis but no ditch. The troops holding that line, from all the information gathered, are Bushrod Johnson's (Tennessee) brigade, about 450 men for duty, with its pickets advanced beyond Cox's overseer's house toward Dutch Gap,holding the line nearly three-quarters of a mile beyond that point to near the Varina road, at a point about 300 yards to the west of which the line of breast-works terminates, to be resumed on the other side of road. The Twenty-fifth Virginia (City Battalion), numbering not to exceed 200 men for duty, are extended along the line toward Ruffin's house, in front of our position at Deep Bottom. They are there joined by Benning's old (Georgia) brigade, commanded by Colonel Du Bose, numbering about 400 men, who are extended along the line past Ruffin's house, the picket-line being near the house of J. Aiken. They are there joined by Gregg's (Texas) brigade, numbering about 400 men for duty, who extend along the line to a place called New Market, where the enemy have a pretty strong work on a height commanding the New Market road. These are all the infantry forces, except a battalion of militia reserves, numbering about 175 men for duty, who are in camp some distance to the rear, who form a connecting line between Johnson's brigade and the City Battalion. These reserves are composed of soldiers below the age of eighteen and above the age of forty-five; but they, with the City Battalion, have never been under fire. At the place marked on the map "Drill-Room" is stationed a regiment believed to be about 400 men, the Seventh South Carolina Cavalry. At the place marked "Sweeney's Pottery" Wade Hampton's Legion, numbering about 400 men, are stationed on the easterly side of Four-Mile Creek and Bailey's Run, apparently to guard the road by which General Hancock advanced over Strawberry Plains from below Four-Mile Creek, and picketing toward Malvern Hill. In the rear, at the intersection of the roads near the point marked "W. Throgmonton" is a regiment, the Twenty-fourth Virginia Cavalry, numbering about 400 men. On Chaffin's farm there is no garrison, except about 100 heavy artillerists, holding that place as an entrenched camp. It is also a camp for the sick and convalescents of the Virginia battalion. There are then no other troops between the