What is the theme in The Ghosts of Cannae: Hannibal and the Darkest Hour of the Roman Republic by Robert L. O'Connell?

One major theme in the novel, The Ghosts of Cannae: Hannibal and the Darkest Hour of the Roman Republic is recorded history. Specifically the different ways in which history is recorded.... the stories, the facts, and the way historical events are so often similar..... parallel.