AMHERST, Mass.—Stephen B. Oates, an award-winning Civil War historian who wrote biographies of Abraham Lincoln, Martin Luther King Jr., Clara Barton, William Faulkner, and others, has died. He was 85. Oates died Friday at his Amherst home surrounded by family after a battle with cancer, officials at the University of Massachusetts Amherst, where he was a professor from 1968 until 1997, said in a statement. Oates received the Robert F. Kennedy Center for Justice and Human Rights book award in 1983. In 1993, the Civil War Round Table of Chicago awarded him the Nevins Freeman Award for Civil War scholarship and biography. He was also a key consultant on filmmaker Ken Burns’ 1990 documentary series “The Civil War.” “Stephen was an extremely valuable advisor to our Civil War series and an informed and passionate participant,” Burns said in a statement released by UMass. “He knew the bottom-up story as well …