The Battle of Chickamauga, fought on September 18–20, 1863, between the United States Army and Confederate forces in the American Civil War, marked the end of a U.S. Army offensive, the Chickamauga Campaign, in southeastern Tennessee and northwestern Georgia. It was the first major battle of the war fought in Georgia and the most significant Union defeat in the Western Theater, and it involved the second-highest number of casualties after the Battle of Gettysburg.
The battle was fought between the U.S. Army's Army of the Cumberland under Maj. Gen. William Rosecrans and the Confederate Army of Tennessee under Gen. Braxton Bragg, and was named for Chickamauga Creek. The West Chickamauga Creek meanders near and forms the southeast boundary of the battle area and the park in northwest Georgia. (The South Chickamauga ultimately flows into the Tennessee River about 3.5 miles (5.6 km) northeast of downtown Chattanooga).