The Twelve Caesars
Just as Graves's Claudius novels ("I, Claudius" and "Claudius the God and his Wife Messalina") were based on "The Twelve Caesars" of Suetonius and other Roman sources, "Count Belisarius" is largely based on Procopius's "History of Justinian's Wars" and "Secret History". However, Graves's treatment of his sources has been criticized by the historian Anthony Kaldellis, who writes that "There are many historical novels set in the early sixth century, but none can be recommended that are both historically accurate and well-written. R. Graves's "Count Belisarius"... is at least well-written."