Livy, a Roman historian writing under Augustus, composed this long History of Rome. Books 11 through 20 are lost, so the surviving text jumps here to Book 21 and the Second Punic War: Rome’s fight with Carthage, a North African power based in what is now Tunisia, a war that nearly wrecked the city. Earlier books had covered Rome’s rise in Italy and the first clash with Carthage; a reader landing here meets the next round without that middle stretch.

The book opens on Hannibal, a Carthaginian general. As a boy he swears lasting hatred of Rome at a Carthaginian altar. He builds a family power in Spain, starves Saguntum — a Spanish city Rome had promised to protect — then leads an army, elephants and all, over the Alps into the Po valley of northern Italy. At the Trebia, ambush, river, and winter cold wreck a Roman force. Rome has not yet grasped that this war is for its life. What follows in later books is the cost of that mistake.