Complex sentence: He served as a Confederate general during the American Civil War, during which he was captured three times, and after the war he led the Alabama Ku Klux Klan and was a U.S. Senator.
Split into simpler sentences: He served as a Confederate general during the American Civil War, during which he was captured three times. After the war he led the Alabama Ku Klux Klan and was a U.S. Senator.