Complex sentence: William Redish Pywell (1843-1887) worked for both Mathew Brady and later, for Alexander Gardner, and his photographs are an important and integral part of the historic photographic record of the American Civil War.
Split into simpler sentences: William Redish Pywell (1843-1887) worked for both Mathew Brady and Alexander Gardner. Pywell's photographs are an important and integral part of the historic photographic record of the American Civil War.