The Emperor: Heraclius Battles Persia for the Life of Rome (Heraclius of Carthage, Book 2) (Unabridged‪)‬

With the empire collapsing about him, Heraclius, the Exarch’s son, becomes the first Roman Emperor in 300 years to lead an army into battle. But this is no ordinary army: it is the Last Army, cobbled together from the bits and pieces that remain of once-great legions. Arrayed against him are the most formidable enemies Rome has ever faced: the Avar horde, the Sassanian Persian Empire intent on Rome’s annihilation, and the relentless plague that exploded under his predecessor Justinian and halved the Roman population. Combined, these apocalyptic forces threaten to extinguish Rome's light, once and for all.