Battle of Chickamauga
The Battle of Chickamauga, fought September 18-20, 1863, marked the end of a Union offensive in south-central Tennessee and northwestern Georgia called the Chickamauga Campaign. The battle was the most significant Union defeat in the Western Theater of the American Civil War.
Benson John Lossing, ed. Harper's Encyclopedia of United States History (vol. 2) (New York, NY: Harper and Brothers, 1912)