In one of the bloodiest battles of the war, the Confederate Army of Tennessee drives the Union Army of the Cumberland back into Chattanooga, Tennessee, from Chickamauga Creek in northern Georgia. Although technically a Confederate victory, the battle had little long-term effect on the military situation in the region.
During the summer of 1863, Union General William Rosecrans had outmaneuvered Confederate General Braxton Bragg. Without fighting any major battles, Rosecrans had moved Bragg out of Tullahoma, Tennessee, and, by September, had captured Chattanooga. Pursuing Bragg into the mountainous region of northern Georgia, Rosecrans gleaned information from Confederate deserters that indicated Bragg was retreating. However, this information was false and had been deliberately fed to the Yankees.
Bragg had hoped to attack Rosecrans and drive the Federals south, away from Chattanooga and Union supply lines. On September 19, a division from Union General George Thomas's corps moved out to strike at what Thomas thought was an isolated Confederate brigade. But his force ran into dismounted Rebel cavalry, and the battle escalated when Bragg sent additional troops to the skirmish. As the day wore on, the battle spread down the lines until both armies were fully engaged.
That night, additional Confederate troops arrived under the command of James Longstreet. Longstreet was part of Robert E. Lee's Army of Northern Virginia, and his men had fought at Gettysburg, Pennsylvania, two months prior. He was dispatched with two of his divisions to stem the tide of Confederate defeat in the West.
Longsteet's appearance paid off for the Confederates. Around noon on September 20, the stalemate broke when Rosecrans ordered General Thomas Wood to move his division to plug a gap in the Yankee line. Although no such gap existed, one was created when Wood moved his division. Longstreet's troops were now able to march through the gap, and the Union line collapsed in chaos. Most of the Union army began a hasty retreat to nearby Chattanooga, leaving Thomas's corps alone on the battlefield. Thomas stubbornly held his ground and halted the Rebel attack, which allowed him to successfully withdraw without further losses. His action earned him the nickname "The Rock of Chickamauga."
Bragg did not immediately pursue Rosecrans to Chattanooga. Instead, the Confederates besieged the city until Union reinforcements arrived in late October. One of the largest battles of the war, Chickamauga resulted in 18,500 Confederate casualties and 16,100 Union casualties.