Question: Joseph Alexander Cooper was an American soldier who commanded units at a battle fought on September 18–20, 1863 and was the first major battle of the war fought where? 
Sentence (from "Battle of Chickamauga"): The Battle of Chickamauga, fought on September 18–20, 1863 between Union and Confederate forces in the American Civil War, marked the end of a Union offensive in southeastern Tennessee and northwestern Georgia — the Chickamauga Campaign.
Relevant evidence: Yes