Complex sentence: At the outbreak of the Civil War, Thomas Dockery received a commission in the Confederate States Army as colonel of the 5th Arkansas State Troops, then given command of the 19th Arkansas Infantry Regiment.
Split into simpler sentences: At the outbreak of the Civil War, Thomas Dockery received a commission in the Confederate States Army as Colonel of the 5th Arkansas State Troops. He was soon given command of the 19th Arkansas Infantry Regiment.