William Lee Miller, a historian and ethicist whose work examined the rocky landscape where religion, morality and American political leadership meet, died on May 27 in Manhattan. He was 86 and lived in Brooklyn.

The cause was congestive heart failure, his wife, Linda, said.

Professor Miller, who had taught for many years at the University of Virginia, was known in particular for his books, written for a general readership, about the roiling national debate over slavery.

Among them are two volumes on Abraham Lincoln, “Lincoln’s Virtues: An Ethical Biography” (2002) and “President Lincoln: The Duty of a Statesman” (2008), and “Arguing About Slavery: The Great Battle in the United States Congress” (1996), which centers on John Quincy Adams....