Historian Patrick K. O'Donnell has written a new book about one of the least-known stories of the Civil War. The story includes Abraham Lincoln, the Secret Service, America's first special forces operation, and a long-forgotten bid by Democrats to rig the 1864 election. It's a dive into long-forgotten American lore that any history buff shouldn't miss. Patrick also answers one of the most hotly-debated questions in American history: Was Robert E. Lee a great man?

Check out Patrick's book, "The Unvanquished," at https://www.amazon.com/Unvanquished-Lincolns-Special-Americas-Operations/dp/080216286X/