Complex sentence: The Battle of Chickamauga, named after the Chickamauga Creek which flowed nearby, was fought September 19--20,1863 and involved more than 150,000 soldiers of the Northern and Southern Armies.
Split into simpler sentences: The Battle of Chickamauga, named for nearby Chickamauga Creek, was fought September 19--20,1863. It involved more than 150,000 soldiers of the Northern and Southern Armies.