The battle of Chickamauga (September 19-20, 1863) developed from the struggle to control the strategic railroad town of Chattanooga, the gateway to the Deep South, the seizure of which President Abraham Lincoln viewed as comparable to the capture of Richmond. In the summer of 1863 Major General William S. Rosecrans, commander of the Union's Army of the Cumberland, successfully forced Braxton Bragg's Army of Tennessee to retreat first from Middle Tennessee and then from Chattanooga. The Federal forces occupied Chattanooga at a cost of only a handful of casualties, shocking the South and elating the North.
Perhaps overly confident, Rosecrans believed Bragg's forces to be in pell-mell retreat and decided to deal the Army of Tennessee a severe blow. He sent three corps into northern Georgia in pursuit of the fleeing army. But the Federal forces traveled on widely separated routes, too far apart to support one another. Unknown to Rosecrans, Bragg halted his retreat and bolstered his army with reinforcements from Mississippi, Knoxville, and Virginia.
By the night of September 18, 1863, the two armies faced each other along the banks of Chickamauga Creek, a name soon translated as “River of Death.” A short distance south of Chattanooga the Federals faced east, with their backs to Missionary Ridge, and in position to protect the road through McFarland's Gap. The Union army numbered approximately fifty-eight thousand men, while the Confederates mustered some sixty-six thousand troops; this was one of the few times the Army of Tennessee would fight with a numerical advantage.
The Confederates attacked on the morning of September 19. Bragg planned to envelop the Union left flank, cutting off their line of retreat through McFarland's Gap and pinning them against the ridge. Major General George H. Thomas's corps, drawn up in a curved line, received the brunt of the Southern attack. Fighting occurred all along the line, with attacks and counterattacks alternating through the dense woods and scattered clearings. The Confederates forced back the Federal troops for a mile or more from the point where the fighting first began but achieved few tactical gains before nightfall ended the first day's struggle.
During the night Lieutenant General James Longstreet arrived with the last of the Confederate reinforcements, and Bragg placed him in charge of the army's left wing. Major General Leonidas Polk commanded the right wing. When the Confederates renewed their effort against the Federals' northern flank, Longstreet attacked the enemy's right center.
Just as the battle seemed destined to end in a draw, fate intervened. Through a misunderstanding at Federal headquarters, an entire division vacated its place in the Union line and created a gap in the line at the point where Longstreet's forces attacked. Rosecrans, two of his three corps commanders, and thousands of Union troops quickly retreated and headed for Chattanooga in a virtual rout.
Thomas, known ever afterward as “the Rock of Chickamauga,” averted disaster by holding the crest of Snodgrass Hill with the help of Major General Gordon Granger's reserve forces until nightfall covered his withdrawal to Chattanooga. The tactical triumph at Chickamauga cost the Army of Tennessee eighteen thousand casualties; the Union suffered sixteen thousand casualties. With Chattanooga still in Union hands, however, the victory at Chickamauga held little strategic meaning for the Confederacy.
Within a few days Bragg's army moved forward and laid siege to Chattanooga. The main force entrenched on Missionary Ridge, east of Chattanooga, while other troops occupied Lookout Mountain, on the southwest side of the town. A third group settled in at Brown's Ferry, across the bend of the Tennessee River, west of Chattanooga. The Confederate positions controlled the railroads to Atlanta and Knoxville, and blocked both the river and the Memphis and Charleston Railroad, cutting off Federal communications with Bridgeport, Stevenson, and Nashville. Confederate morale at the top levels of command sank so low due to constant bickering, however, that President Jefferson Davis visited the army in early October. He listened to Bragg's critics, but kept the unpopular general in command.
On the Union side, President Abraham Lincoln replaced Rosecrans, who seemed incapable of recovering from the shock of the loss at Chickamauga. On October 18, Lincoln named Major General Ulysses S. Grant as commander of the forces at Chattanooga. At the same time, the Federals prepared to reinforce their position with Major General William T. Sherman's Army of the Tennessee and Major General Joseph Hooker's troops from the Army of the Potomac.
Grant reached Chattanooga on October 23 and learned the seriousness of the Federal supply situation. In a surprise attack, the Union troops drove off Confederate troops and erected a pontoon bridge across the Tennessee River. A second skirmish at Wauhatchie secured Federal communications lines. By late November the Union forces in and around Chattanooga numbered almost seventy thousand, but the Confederates had depleted their fighting strength to about forty thousand after sending Longstreet's men to Knoxville in a futile effort to take that city.
Grant devised a simple plan of attack. He placed Hooker on the right and Thomas in the center to create diversions at Lookout Mountain and the southern center on Missionary Ridge. He assigned Sherman to the main task of assaulting the northern end of Missionary Ridge to break the Confederate right flank and sweep down the ridge.
The battle did not develop as planned. On November 23, Thomas occupied Orchard Knob, a foothill far in front of the Confederate center on Missionary Ridge. The next day Hooker drove back the Southerners between the river and Lookout Mountain. The troops he sent up the mountain disappeared in the mist but succeeded in taking the pinnacle, from which the United States flag flew the next morning. Newspapers romanticized the episode by calling it the “Battle Above the Clouds.”
On November 25 Sherman attempted to carry out his mission, while Hooker fought for a position on the Confederate left, and Thomas moved against the center. Sherman's troops made no headway against the one (reinforced) division of Major General Patrick R. Cleburne. The Federals added two more divisions to no avail. The limited space to deploy Union troops, the determined fighting by Confederates, and Cleburne's masterful choice of position undermined the Union plan.
About three o'clock in the afternoon, a concerned Grant ordered Thomas to move out and occupy the enemy's rifle pits at the base of the ridge. After advancing and seizing this objective, the troops from the Army of the Cumberland, without orders, charged up the steep slope of the ridge in one of the most remarkable and decisive acts of the war. The avalanche of blue-clad soldiers poured over the crest of the ridge, routing the badly positioned Confederate center and forcing the entire army to fall back into North Georgia. Each side suffered about six thousand casualties. Bragg lost command of the Army of Tennessee, while Grant now possessed the most enviable reputation of any Union general. For the first and only time in the war, the four most successful Union generals–Grant, Sherman, Thomas, and Philip H. Sheridan–served together. More importantly, however, the Union forces controlled the strategic town of Chattanooga.
Key portions of the battlefield are preserved and interpreted at the Chickamauga-Chattanooga National Military Park, a unit of the National Park Service, which maintains its visitor center in Georgia but preserves and interprets several key aspects of the battles, including property along Missionary Ridge and on Lookout Mountain, in Tennessee.