Lead: One hundred and fifty years ago the Republic was facing its greatest crisis. This continuing series examines the American Civil War. It is "A House Divided."

Intro: A Moment in Time with Dan Roberts.

Content: In the history of the American Republic, there is nothing that compares to slavery. It divided the infant nation, at least in part provoked and sustained the greatest war in U.S. history, philosophically poisoned the national charter, retarded the economic development of one of great America’s regions and probably skewed that of all others, and dominated the national conversation for seven decades. It also complicated and excavated one of the important fault lines running through the American experience: the great debate over federal and state power.