How Did the Romans Recover From Their Devastating Defeat at the Battle of Cannae?

It is believed that between the battles of Trebia, Trasimene and Cannae, twenty percent of Italian men of military age perished. At the Battle of Cannae alone, some 55,000 Romans and allies were killed

In addition to losing all of those soldiers, after Cannae a lot of cities, towns and tribes that had been allied with the Romans went over to Hannibal. These included Capua, Metapontum, Croton, Locri, Arpi, and, eventually Tarentum. Tribes that sided with Hannibal included the Atellani, the Calatini, the Hirpini, some of the Apulians, the Samnites except for the Pentrians, the Bruttians, the Lucanians and the Surrentinians. Most of the Gauls of Cis-Alpine Gaul had already allied with Hannibal before Cannae. Naples and Nola stayed loyal to Rome, as did all the tribes of Latium.

In 215 B.C. the year after Cannae, Syracuse also allied itself with Hannibal.

After Cannae Hannibal expected the Romans to sue for peace and he sent his envoy, the Carthaginian nobleman Carthalo to the city with peace terms. The Romans wouldn’t even let him into the city, and the Senate declared it a crime to even mention the word “peace.”

The Romans took the unusual step of recruiting ten thousand slaves as soldiers upon the promise of granting them freedom if they served well. They were led by Tiberius Gracchus. The Romans levied everyone they could from the Latin confederacy. By 209 B.C. some of the cities refused to comply with the levies, saying they had no more men to spare. The survivors of the Battle of Cannae were organized into two legions and not permitted to leave service until the end of the war. They fought under Claudius Marcellus, and eventually fought at the battle of Zama in 202 B.C. under Scipio Africanus.

After Cannae the leadership in Rome devolved upon Quintus Fabius Maximus. Fabius had been dictator in 217 B.C. and had studiously avoided confronting Hannibal on his own terms. The Romans had rejected his strategy, but after the disastrous battle of Cannae, they went back to it. He was, in fact the only game in town. The war became, largely, one of attrition and the Romans gradually clawed back the territorial gains that Hannibal had made. They concentrated on punishing his allies rather than confronting Hannibal on the battlefield. They laid siege to Capua and when the city finally surrendered, they executed the leaders and sold the population into slavery. They retook Tarentum by a ruse and also sold the population into slavery. When Claudius Marcellus took Syracuse in 212, he did spare the population, although he looted the monuments.

By 205 B.C. Hannibal was contained to a small territory in Bruttium, where he remained until summoned back to Africa to confront Scipio in 202 B.C.