The Confederate tactical victory at Chickamauga was a maker and breaker of reputations. Thomas's performance elevated him to top command, and Granger was also given more responsibility. Rosecrans, Alexander McCook, Crittenden, and Negley were relieved. Confederate Commanding General Bragg also relieved Polk, D.H. Hill, and Hindman for unsatisfactory performance during the campaign all causing major leadership shifts in the Confederate army.
At Chattanooga Lincoln placed the perilous situation in the hands of Ulysses S. Grant. Losing no time, Grant launched assaults that cleared the Confederates from their positions on the heights of Lookout Mountain and Missionary Ridge. The South would never recover from the loss of Chattanooga, which brought Bragg's relief and opened the gateway to the Confederate heartland. More importantly this victory thrust U.S. Grant to the forefront as the overall commander of the Union forces.