His face is on the penny. His god-like statue reigns over Washington, DC. He saved the Union, freed the slaves, and immortalized the Battle of Gettysburg with the famous words "Four score and seven years ago." There can be no doubt in American minds that Abraham Lincoln stands among the most honorable and heroic of our presidents-or does he? In a thorough and well-researched argument, Walter Donald Kennedy, the controversial co-author...