As the battle was ordered for daylight, it seemed too late to draw Buckner’s divisions into reciprocal relations, and we had yet to find the right wing. As it was not in touch or sight, General Stewart was ordered to find it. He marched about half a mile to his right and found that he was nearly half a mile in advance of the right wing. His move made place for Hood’s column, which was called to the line, and General Stewart broke his right to rear to guard that flank until the right wing could get to the front. The divisions were formed in two lines, two brigades on the front line, others of the second line in support, except Hood’s five brigades in column. General McLaws and two of his brigades, two of Hood’s, and Alexander’s artillery were on the rails, speeding for the battle as fast as steam could carry them, but failed to reach it. When organized for battle the left wing stood about three hundred yards east of the Lafayette-Chattanooga dirt road. As the battle was ordered for wheel to the left on Preston’s division as pivot, his (Trigg’s) brigade was echeloned on the left of Hindman’s division. The purpose of the commander in ordering the wheel on the left as pivot was to push in, from the start, between the enemy and his new base at Chattanooga.
No chief of artillery for the command reported, and a brief search failed to find one. The field, so far as it could be surveyed, however, was not a field, proper, but a heavy woodland, not adapted to the practice of artillery. The hour of battle was at hand, but the right wing was not yet organized. Some of the troops were without rations, their wagons, having lost the lines of march through the woodlands, failing to reach them until after daylight, when they were further delayed cooking their food.
The right wing was formed of D. H. Hill’s corps, Breckenridge’s and Cleburne’s divisions, W. H. T. Walker’s corps of Walker’s and Liddell’s divisions, Cheatham’s division of Polk’s corps, artillery battalions of Majors Melancthon Smith, T. R. Hotchkiss, and R. E. Groves, and batteries of Lieutenant R. T. Beauregard, Captain E. P. Howell, Captain W. H. Fowler, and Lieutenant Shannon.
As it formed it stood with D. H. Hill’s corps on the right, Breckenridge’s and Cleburne’s divisions from right to left, Cheatham’s division on the left of Cleburne’s rear, and Walker’s reserve corps behind Hill’s corps; but when arranged for battle it was about half a mile in rear of the line upon which the left wing was established. The Confederate commander rode early in the morning to hear the opening of the battle. As the sounds failed to reach him, he became anxious, sent orders of inquiry for the cause of delay, and repeated his orders for attack, and finally rode to his right wing and gave peremptory orders.
Marching through the woods to line up on the left wing, the left of the right wing was found to overlap my division on the right, yet our extreme right was found to overreach the left of the enemy’s field-works by two brigades, and reconnoissance found the road between the enemy and Chattanooga open and free of obstructions or troops to defend it. On the right of Breckenridge’s division was Armstrong’s division of cavalry dismounted, and beyond his right was Forrest’s other division of cavalry, Pegram’s. Some miles off from our left was Wheeler’s division of cavalry, under Wharton and Martin.
The Union army from left to right was: first the Fourteenth Corps, General George H. Thomas commanding, four divisions,—Baird’s division on the left, then Reynolds’s and Brannan’s, the latter retired to position of reserve, and Negley’s. (The last named had been left, on the night of the 19th, on guard near the Glen House, but was ordered early on the 20th to join General Thomas, and one of the brigades did move promptly under the order; the other brigades (two) failed to receive the order.) Then the Twentieth Corps, three divisions,—Jefferson C. Davis’s, R. W. Johnson’s, and P. H. Sheridan’s,—on the right, General A. McD. McCook commanding the corps. Next was the Twenty-first Corps, three divisions,—T. J. Wood’s, J. M. Palmer’s, and H. P. Van Cleve’s,—General T. L. Crittenden commanding the corps. It was in position on the east slope of Mission Ridge, ordered to be prepared to support the corps of the right or left, or both; one of its brigades had been left to occupy Chattanooga. Wilder’s mounted infantry, on the right of the Twentieth Corps, was ordered to report to the commander of that corps for the day’s work. A reserve corps under General Gordon Granger was off the left of the Union army to cover the gap in Mission Ridge at Rossville and the road from the Union left to that gap. Minty’s cavalry was with this corps, and posted at Mission Mills. General Granger had Steedman’s division of two brigades and a brigade under Colonel D. McCook. General R. B. Mitchell, commanding Union cavalry, was on their right at Crawfish Springs, with orders to hold the crossings of the Chickamauga against the Confederate cavalry.
It seems that parts of the Twentieth and Twenty-first Corps, Johnson’s and Van Cleve’s divisions, were under General Thomas in the fight of his left on the 19th, and remained with him on the 20th. The purpose of the posting of the Union army was to hold open its routes for Chattanooga by the Rossville and Dry Valley roads. As before stated, the Confederate commander’s design was to push in between the Union army and Chattanooga, recover his lost ground, and cut the enemy’s line of supplies.
The commanders of the armies were on the field early on the 20th. The failure of the opening of the Confederates at daylight gave opportunity for a reconnoissance by light of day, by which it was learned that the road from the Union left was open, not guarded nor under close observation; but the commander ordered direct assault under the original plan,—his back to the river, the Union army backing on Mission Ridge. The Chickamauga River, rising from the mountains south, flows in its general course a little east of north to conflux with the Tennessee River. The Ridge runs nearly parallel with the river, and opens up a valley a mile wide. It is a bold outcropping of limestone about one hundred feet above the valley, with occasional passes, or gaps, that are strong points of guard for defence. Four miles northwest from the Union left was the gap at Rossville, called for the old Cherokee chief. On its right was the pass of the Dry Valley road, and immediately in its rear was the McFarland Gap. The line of the Lafayette road lies about parallel with the Ridge to within a mile of the Union left, when it bends westward and leads to the Rossville Gap. The Dry Valley road crosses the Chickamauga at Glass’s Mills, courses along the east slope of the Ridge, crosses it, and joins on the west the road that crosses at the McFarland Gap.
The Union left was east of the Chattanooga-Rossville road, but crossed the road to the west and formed in broken front. The left and right of Thomas’s line was retired or broken to the rear. The Union commander rode over his lines on the afternoon of the 19th and ordered his front covered by such field-works as could be constructed during the night.
General Thomas covered his lines by log and rail obstructions. The corps of Rosecrans’s right formed two lines of rail defences for infantry. The batteries had the ascending slopes of the Ridge for positions, and their field was more favorable otherwise for artillery practice than was that of the Confederates advancing from the valley and more densely timbered forests. They had two hundred and forty-six guns. The records do not give satisfactory accounts of the number of Confederate guns, but they probably numbered not less than two hundred.