THE BATTLE ON MONDAY.

The line of battle agreed upon for the Union forces on Monday was this:—Right wing, Major-General Lew. Wallace; left wing, Brigadier-General Nelson. Between these, beginning at the left, Brigadier-Generals T. Crittenden, A. McD. McCook, Hurlbut, McClernand and W. T. Sherman. In the divisions of the three latter were to be included also the remains of Prentiss’ and W. H. L. Wallace’s commands—shattered and left without commanders, through the capture of one, and the mortal wound of the other.

Buell’s three divisions were not full when the battle opened on Monday morning, but the lacking regiments were gradually brought into the rear. The different divisions were composed of the following forces:

Brigadier-General Nelson’s Division.—First Brigade—Col. Ammon, 24th Ohio, commanding; 36th Indiana, Col. Gross; 6th Ohio, Lieut.-Col. Anderson; 24th Ohio, Lieut.-Col. Fred. C. Jones. Second Brigade—Saunders D. Bruce, 20th Kentucky, commanding; 1st Kentucky, Col. Enyard; 2d Kentucky, Col. Sedgwick; 20th Kentucky, Lieut.-Col. ——, commanding. Third Brigade—Col. Hazen, 41st Ohio, commanding; 41st Ohio, 6th Kentucky and 9th Indiana.

Brigadier-General T. Crittenden’s Division.—First Brigade—Gen. Boyle; 19th Ohio, Col. Beatty; 59th Ohio, Col. Pfyffe; 13th Kentucky, Col. Hobson; 9th Kentucky, Col. Grider. Second Brigade—Col. Wm. S. Smith, 13th Ohio, commanding; 13th Ohio, Lieut.-Col. Hawkins; 26th Kentucky, Lieut.-Col. Maxwell; 11th Kentucky, Col. P. P. Hawkins; with Mendenhall’s regular and Bartlett’s Ohio batteries.

Brigadier-General McCook’s Division.—First Brigade—Brig.-Gen. Lovell H. Rousseau; 1st Ohio, Col. Ed. A. Parrott; 6th Indiana, Col. Crittenden; 3d Kentucky (Louisville Legion); battalions 15th, 16th and 19th regulars. Second Brigade—Brig.-Gen. Johnston; 32d Indiana, Col. Willich; 39th Indiana, Col. Harrison; 49th Ohio, Col. Gibson. Third Brigade—Colonel Kirk, 34th Illinois, commanding; 34th Illinois, Lieut.-Col. Badsworth; 29th Indiana, Lieut.-Col. Drum; 30th Indiana, Col. Bass; 77th Pennsylvania, Col. Stambaugh.

Major-General Lew. Wallace’s Division—Right of Army.—First Brigade—Col. Morgan L. Smith, commanding; 8th Missouri, Col. Morgan L. Smith, Lieut.-Col. James Peckham, commanding; 11th Indiana, Col. George F. McGinnis; 24th Indiana, Col. Alvin P. Hovey; Thurber’s Missouri battery. Second Brigade—Col. Thayer (1st Nebraska) commanding; 1st Nebraska, Lieut.-Col. McCord, commanding; 23d Indiana, Col. Sanderson; 58th Ohio, Col. Bausenwein; 68th Ohio, Col. Steadman; Thompson’s Indiana battery. Third Brigade—Col. Chas. Whittlesey (20th Ohio) commanding; 20th Ohio, Lieut.-Col. —— commanding; 56th Ohio, Col. Peter Kinney; 76th Ohio, Col. Chas. R. Woods; 78th Ohio, Col. Leggett.

At daylight it became evident that the gunboat bombardment through the night had not been without a most important effect. It had changed the position of the rebel army. The sun had gone down with the enemy’s lines encircling the Union forces closely on the centre and left, pushing them to the river, and leaving them little over half a mile of all the broad space they had held in the morning. The gunboats had cut the coils and loosened the anaconda-like constriction. Their shells had made the old position on the extreme Union left, which the rebels had been occupying, utterly untenable. Instead of stealing upon their foe in the night, which was doubtless their intention, they were compelled to fall back from point to point out of range of the shells which came dropping in; go where they would within range, the troublesome visitors would find them out, and they fell back beyond the inner Union camps, and thus lost more than half the ground they had gained the afternoon before.

Less easily accounted for was a movement of theirs on the right. Here they had held a steep bluff, covered with underbrush, as their advanced line. Through the night they abandoned this, the best possible position for opposing Lew. Wallace, and had fallen back across some open fields to the scrub oak woods beyond.

To those who had looked despairingly at the prospects on Sunday evening, it seemed unaccountable that the rebels did not open the contest by daybreak. Their retreat before the bombshells of the gunboats, however, explained the delay. The Union divisions were put in motion almost simultaneously. By seven o’clock Lew. Wallace opened the day by shelling the rebel battery, of which mention has been made, from the positions he had selected the night before. A brisk artillery duel was followed by a rapid movement of infantry across a shallow ravine, as if to storm; and the rebels, enfiladed and menaced in front, limbered up and made the opening of their Monday’s retreating.