This is the first Harry Turtledove book I read and is a very interesting time travel book. Rebel sympathizers travel back in time and supply the South with assault rifles during the Cvil War (or War of Northern Aggression). The South must still struggle and the book deals with many of the ramifications of a sudden influx of higher tech guns (and people) into the Civil War South. This book is a very good read and I highly recommend it.