In AD 9, the German Arminius who had served as an auxiliary in the Roman army persuaded P. Quinctilius Varus, Roman governor of newly conquered Germany, to take his army to winter quarters in a way that allowed hostile German forces to wipe out the Roman garrison of three legions at the Teutoburg Forest, effectively ending the Roman attempt to turn Germany into a Roman province. This novel is an okay effort to investigate how this took place. It reminds me a lot of the work of Bernard Cornwall. The book mainly revolves around the plot and the characters are underdeveloped. Both they and the story signify nothing much beyond the plot. There is no "backstory," the characters learn nothing, and the writing doesn't really give much texture to the story. You have characters interact, and the narrative does nothing much beyond giving the setting for the dialogue.
The story is basically about Arminius and Varus, and each has a side kick (a slave assistant in the case of Varus, while Arminius has his father). There are a few other characters on the Roman side. These are just insubstantial soldiers, who are hard to tell apart because they have no story of the own (either in the immediate setting or as "backstory"). They basically serve as foils to Varus's actions, and when they finally participate in the climactic debacle, their final stories have make little impact. There are a few Germans running around apart from Arminius and his father, but they don't count for much.
Overall, the book does a pretty good job of explaining how Varus could have done something that in retrospect seems to monumentally stupid, and it's interesting enough in that regard. But there really isn't much too it beyond that, and even the final battle is portrayed in a rather unengaging way. The action isn't all that vivid, and the readers doesn't have enough investment in the characters to care that much about their fates.
The book doesn't have enough substantial detail to give rise to an overall evaluation of its historical accuracy, but there are a few signs of a less than full understanding of the period on the author's part. He seems to think that it was possible for a senator like Varus to become governor of Egypt, though it's a pretty rudimentary element in the system set up by Augustus that Egypt was anomalously governed by an equestrian-rank prefect (senators were actually forbidden from setting foot there without imperial permission, and Tiberius's nephew and adopted-heir Germanicus got into some trouble for visiting the place without permission despite being a sort of plenipotentiary in the east). Also, Varus's slave assistant is constantly referred to by the title pedisequus, but that's actually a very lowly function (the term literally means "foot follower" and signified a flunky who would accompany the master on foot). And in the name of the gods, Roman personal nomenclature, while different from our own, isn't all that complicated, and it drives me nuts when the writers of historical fiction screw them up, as here.
So, overall an okay investigation of the motivations and behavior of the two main protagonists, but not all that engaging. For example, the final scene when Augustus gets word of the debacle has no real emotional heft, and is defective historically speaking in that while the Pannonian revolt of AD 6-9 is occasionally alluded to, no mention is made of the fact that the disaster at the Teutoburg Forest was so final derived from the fact that during the Pannonian Revolt Augustus had found it very difficult to come up with reinforcements, and after that effort, it was pretty much impossible to make good the loss of about 10% of the overall Roman military force as a result of Varus's bungling.