Besides his illustrious name, the Union general Jefferson Columbus Davis is best known for two appalling actions: the September 1862 murder of General William "Bull" Nelson -- his former commanding officer -- and the abandonment of hundreds of African American refugees to the mercy of Confederate cavalry at Ebenezer Creek during Sherman's march through Georgia in 1864. Historians have generally dismissed Davis (1828--1879) as a reckless assassin, a racist, a journeyman soldier at best, and an embarrassment to the Lincoln war effort. But Nathaniel Cheairs Hughes, Jr., and Gordon D. Whitney...