Complex sentence: Walter R. Borneman (born January 5,1952), an American historian and lawyer, is the author of well-known popular books on 18th and 19th century United States history.
Split into simpler sentences: Walter R. Borneman (born January 5,1952), an American historian and lawyer. He is the author of well-known popular books on 18th and 19th century United States history.