(Nov. 23–25, 1863) Decisive engagement of the American Civil War .
The battle was fought at Chattanooga, Tenn., a vital railroad junction. A Confederate army under Braxton Bragg besieged a Union army in September 1863, and to lift the siege, Union troops under Ulysses S. Grant marched on Bragg's troops. At battles on Lookout Mountain and Missionary Ridge, the Union troops forced the Confederate army to retreat. With this victory, the North was poised to split the South horizontally by marching across Georgia to the sea. See also Battle of Chickamauga .