General Granger, without orders and following the sound of battle, had hastened to the aid of Thomas. He arrived at Snodgrass Hill at a very opportune moment and just in time to stop the Confederates from enveloping Brannan’s right. A fierce engagement took place as Brig. Gen. James B. Steedman’s Division of Granger’s Corps forced the southern troops from the crest of the hill.

Midafternoon found Longstreet once again attempting to wrest the hill from Thomas’ troops, using McLaw’s, Hindman’s, and Bushrod Johnson’s Divisions, and again he was repulsed. Later in the afternoon, Longstreet asked Bragg for reinforcements but was told none were available and that the right wing “had been beaten back so badly that they could be of no service” to him. Longstreet determined to make one more effort. He formed a column of such troops as were available and again assaulted the hill. The fight was desperate and lasted until nightfall. The Union troops repulsed some of the Confederate charges with the bayonet as their ammunition was nearly exhausted. Finally, Longstreet pushed Steedman back to the next ridge and occupied the ground to the right of Brannan.

The left of the Union line around Kelly Field spent a relatively quiet afternoon compared to their comrades on Snodgrass Hill. However, about 4 p.m., the divisions of Hill’s corps and part of Walker’s again assaulted the Union positions there. By 6 p.m., Cheatham’s Division had joined the attack. This attack succeeded in enveloping the Union left, and the road to Rossville, through Rossville Gap, was cut off for the moment.

Headquarters, Maj. Gen. Gordon Granger, Reserve Corps, Army of the Cumberland, at Rossville Gap. The house was built by John Ross, Cherokee Indian Chief, who lived in it until 1832. Ross gave his name to the village in the gap. From Elson, The Civil War Through the Camera.

In the meantime, Thomas received orders from Rosecrans to “Assume command of all the forces, and with Crittenden and McCook take a strong position and assume a threatening attitude at Rossville.” Although Thomas received these orders with little delay, it was late afternoon before he sent instructions to Reynolds to begin the withdrawal and move into position to cover the retirement of the other troops on the left. In executing this movement, Reynolds was forced to drive off the Confederate troops who had begun to envelop the Union left. The Union army withdrew in relatively good order. The troops holding Kelly Field moved out first, followed by those who had stubbornly resisted Longstreet’s attacks upon Snodgrass Hill.

While the retreat from the battlelines may have been in “good order,” General Beatty’s description of the march to Rossville amply describes the scene: “The march to Rossville was a melancholy one. All along the road, for miles, wounded men were lying. They had crawled or hobbled slowly away from the fury of the battle, become exhausted, and lain down by the roadside to die.” Beatty reached Rossville between “ten and eleven” and reported, “At this hour of the night (eleven to twelve o’clock) the army is simply a mob. There appears to be neither organization nor discipline. The various commands are mixed up in what seems to be inextricable confusion.”

Nevertheless, Thomas placed his forces at Rossville Gap and along Missionary Ridge in preparation against further attacks. The morning of the 21st found the Union Army of the Cumberland more or less reorganized. With the exception of some skirmishing, the Union forces were not molested.

The losses on both sides were appalling and the percentages surprisingly equal. The following tabulation of casualties at the Battle of Chickamauga is based on Thomas L. Livermore’s Numbers and Losses in the Civil War in America, 1861-65:

Army Total Strength Total Casualties Killed Wounded Missing Percent Casualties
Union 58,222 16,170 1,657 9,756 4,757 28
Confederate 66,326 18,454 2,312 14,674 1,468 28