Complex sentence: Couch requested reassignment after quarreling with Maj. Gen. Joseph Hooker, and he commanded the newly created Department of the Susquehanna during the Gettysburg Campaign in 1863.
Split into simpler sentences: Couch requested reassignment after quarreling with Maj. Gen. Joseph Hooker. He commanded the newly created Department of the Susquehanna during the Gettysburg Campaign in 1863.