Settling Accounts: Return Engagement by Harry Turtledove is the first book of the third series that Turtledove has written in his alternate history series that postulates what the world would be like if the South had won the American Civil War and successfully secceded from the United States of America. In this series, the timeline has advanced up to the 1940s and World War II. In previous books in this timeline, Turtledove has detailed a second American Civil War, World War I, the reconstruction period afterwards, and now WWII. The easiest way to describe the book is to say that it's similar to most other Harry Turtledove alternate history books. I you haven't read any Turtledove, then you might think this is criticism. Those of you who have read his work know that this simply means that he sticks to his successful formula of telling a gripping story using about a dozen primary point of view characters, and easily over a hundred characters overall to tell a complex story and delves into all aspects of the war and it's impact on society.
In this timeline, the USA won WWI and soundly defeated the Confederate States of America (CSA), and ever since they, they chafed at the harsh economic ruin imposed on them by their neighbor. This allowed the radical and hate filled Jake Featherson to rise to power and drive his country towards a looming confrontation with the USA. The previous series, American Empire, details this rise to power, and Settling Accounts starts right with the first unannounced attack on the USA. Turtledove does his always excellent job of using his characters to show a variety of points of view, on both sides of the conflict. He includes not only the ground war from both an infantry, armor, and general's point of view, but also views into the war at sea and in the air, the politics on both sides of the conflict, espionage, the home front, and also the harsh world that blacks are forced to live in under CSA rule. One of the central elements of the story is how Jake Featherson's personal vendetta against blacks drives him fully into the role that Adolf Hitler held in our real history, but replacing Hitler's hatred of Jews with Featherson's hate towards blacks. It's both fascinating and horrifying to read about the same kinds of atrocities happening on American soil that happened in Nazi Germany, and how easy Turtledove shows it could therefore happen anywhere, under the right circumstances.
I can't recommend this book enough. Even Turtledove's worst book is well worth reading, and this is one of his better ones. In addition to his signature multiple viewpoint characters, he does an excellent job of weaving real life historical figures into the lives of his fictional main characters, as well as showing how even small events can lead to large consequences or significant discoveries.