Between 218 and 216 BC Hannibal destroyed three Roman armies in Italy, and Rome did not sue for peace, which is the fact the whole of the rest of this course depends on.
The previous lesson ended with Carthage rebuilding in Spain under the Barcid family, out of reach of the Roman fleet and paying for itself with Iberian silver and Iberian recruits. Hannibal, who took over that command in 221 BC, understood what the first war had taught: Rome could not be beaten at sea and could not be beaten by attrition, so it would have to be beaten politically, by detaching the Italians who supplied half its army. Everything he did in Italy for fifteen years follows from that plan, and the plan is the reason his victories did not win the war.
The invasion
The immediate trigger was Saguntum, a city in Spain under Roman protection, which Hannibal besieged and took in 219 BC. Rome declared war, expecting to fight in Spain and Africa. Hannibal marched to Italy instead, over the Alps, arriving in the autumn of 218.
The march cost him most of his army. Polybius, who says he used an inscription Hannibal set up in southern Italy recording his own numbers, gives 90,000 foot and 12,000 horse leaving New Carthage and 20,000 foot and 6,000 horse arriving in the Po valley. That is 102,000 down to 26,000, a loss of 76,000 men or 75 per cent, of whom many were detached as garrisons and some were sent home rather than lost.
With that remnant he beat a Roman army at the Trebia in December 218, ambushed and destroyed another at Lake Trasimene in June 217, killing a consul, and in August 216 met the largest army Rome had ever put in the field at Cannae.
Cannae
Polybius gives the Roman force as about 80,000 foot and 6,000 horse against Hannibal's 40,000 foot and 10,000 horse. Hannibal formed his infantry in a forward curve that gave way as the Romans pushed into it, held the flanks with his African veterans, and used his superior cavalry to clear the field and come in behind. The Roman army was surrounded and killed where it stood.
Example. Polybius puts the Roman dead at 70,000; Livy gives 48,200. Convert both to proportions and consider what the difference is worth.
Against a force of 86,000, Polybius's figure is 81 per cent killed and Livy's is 56 per cent. Both are catastrophic and they describe different events: 81 per cent is an annihilation with no possibility of flight, 56 per cent is a rout in which nearly half got away. Polybius wrote earlier, used family archives and had a particular interest in military mechanics; Livy names a source count that includes survivors regrouping at Canusium, which fits his lower number. The honest position is that the true figure is somewhere in that band and that the choice does not change the argument. Even the low figure is a death toll no ancient state was expected to survive politically.
Now you. Take Polybius's 70,000 dead and suppose the killing occupied about six hours. What rate does that imply, and what does the number tell you about the mechanics of the battle?
Answer
Roughly 194 deaths a minute, sustained for six hours, every one of them inflicted with a hand weapon. A rate like that is impossible in a battle line where two fronts push at each other, because the killing surface is limited to the men in contact. It is only possible when a formation has been surrounded and compressed so that the outer ranks cannot escape and the inner ones cannot fight, which is exactly what Polybius describes. The arithmetic is a check on the tactics: the encirclement is not a literary flourish, it is what the casualty figure requires.
The refusal
What happened next is the reason Cannae is remembered as a Roman disaster and not as the end of Rome. Eighty senators had died in the battle. Capua, the second city of Italy, went over to Hannibal, and so did much of the south. Syracuse changed sides in 214, Philip V of Macedon allied with Carthage in 215.
Rome did not negotiate. It refused to ransom the prisoners Hannibal held, at a price he had set low precisely to make the offer attractive, and Polybius treats the refusal as the key to Roman character: the Senate calculated that buying men back would teach every future army that surrender was survivable. It enrolled 8,000 slaves as soldiers, bought from their owners at public expense, and armed them with weapons taken from temple walls. It appointed Fabius Maximus, who avoided battle for a year and was mocked for it, and then adopted his strategy anyway. It kept as many as twenty-five legions in the field in 212 and 211 BC, which at Polybius's establishment is about 105,000 citizen soldiers, close to 39 per cent of the 270,713 adult male citizens the census had recorded in 234 BC.
The census figures record the strain. The count for 209 BC gives 137,108 citizens against 270,713 twenty-five years earlier, a fall of 49 per cent. Part of that is dead men and part of it is a state too disrupted to register them, and no reading of it is comfortable.
Example. Why did the Senate refuse to ransom the prisoners after Cannae, when it was simultaneously arming slaves?
Because the two decisions answer different questions. Arming slaves solves a shortage of bodies at a moment when bodies are the constraint. Ransoming prisoners would solve the same shortage and destroy something the Republic could not replace: the expectation that a Roman army fights until it wins or dies. Polybius makes this explicit and treats it as the deliberate maintenance of an incentive, not as cruelty or pride. Read as policy it is coherent and cold: the state bought men from slave owners because that transaction changed nothing about what a citizen soldier could expect, and refused to buy men from Hannibal because that transaction would have changed everything.
Now you. In 209 BC, twelve of the thirty Latin colonies told the Senate they could supply no more men or money. Which half of that sentence is the striking one?
Answer
The eighteen that could and did. Twelve refusals after eleven years of continuous war, with Hannibal still in Italy, is exhaustion rather than disloyalty, and none of the twelve went over to the enemy. What needs explaining is that sixty per cent of the colonies kept supplying men into the twelfth year of a losing war, and that not one Latin colony defected in the whole conflict. That is the strongest single piece of evidence that the settlement of 338 BC worked: the communities Rome had planted or promoted stayed with it under the only pressure that could have tested them.
Why the alliance held
Hannibal's plan was to break Italy off, and it half worked. Capua, Tarentum and most of the Samnite and Lucanian country went over. The Latin colonies, the Etruscan and Umbrian cities, the Greek cities of the far south under Roman garrison, and central Italy did not.
Three reasons stand out. The first is that Rome had bound the local aristocracies to itself rather than the populations: defection required a city's ruling class to bet its property on a Carthaginian victory, and after Cannae many did, and after 211 the survivors of Capua's ruling class were executed and its territory confiscated, which was noticed everywhere else. The second is that the colonies were not subject towns but Roman and Latin populations living on land Rome had given them, whose neighbours would take it back the moment Rome fell. The third is that Hannibal could offer only revenge and a share of the fighting, since he never took Rome and never destroyed Rome's capacity to punish a defector the following season.
So the answer to the question the settlement posed in 338 BC arrived in 216 BC and was favourable. It is worth being precise about what it proves. It does not prove the allies were content; a third of Italy rose the moment a credible alternative appeared. It proves that Rome had made defection expensive and loyalty survivable for the men who made the decision.
Scipio, and a command that broke the rules
The war was won by a young man operating outside the constitutional rules the Republic had built to contain imperium.
Publius Cornelius Scipio was about twenty-five in 210 BC and had held only the aedileship when the assembly voted him proconsular imperium for the war in Spain, where his father and uncle had just been killed. He was a private citizen with the powers of a consul, appointed by the people to a theatre of war for an indefinite term. There was no precedent for it. He took New Carthage in 209, cleared Spain by 206, was elected consul for 205 despite being years under the legal age, crossed to Africa in 204 against strong senatorial opposition, and at Zama in 202 beat Hannibal, who had been recalled to defend Carthage.
Every element of that career reappears in the last century of the Republic: the command voted by the people rather than assigned by the Senate, the age rules waived, the theatre held for years, the army whose loyalty is to the man who leads it, and the popular general the Senate cannot control and eventually prosecutes. Scipio was investigated in the 180s over the accounting of the Antiochus campaign and left Rome for his estate at Liternum, where he died. The Republic had solved the Hannibalic emergency by suspending its own rules, and the solution proved habit-forming.
Example. In 210 BC the assembly gave imperium to a private citizen who had never held the praetorship or the consulship. Which of the Republic's constraints on imperium does that break, and which does it leave standing?
It breaks the cursus honorum, since imperium is being conferred outside the ladder of offices, and it breaks the Senate's practical monopoly on assigning commands, since the appointment came from a popular vote. It leaves annuality nominally standing, since the command was renewable rather than permanent, and it leaves collegiality untouched, since Scipio's imperium did not override the consuls'. That mixture is what makes the precedent dangerous rather than revolutionary: nothing in it declares the constitution void, and each element of it can be defended as an emergency measure, which is exactly what Pompey's supporters said in 67 BC.
Now you. The peace of 201 BC required Carthage to pay 10,000 talents over fifty years, against the 3,200 over ten imposed in 241. Compare the two and say what the difference is designed to do.
Answer
The total is 3.1 times larger and the term is five times longer, so the annual burden is 200 talents against 320, about 4.8 million sesterces a year. The second indemnity is therefore lighter per year and far longer, and that is the point: the first was a fine, the second is a fifty-year leash. Combined with the clauses limiting Carthage to ten warships and forbidding it to make war outside Africa without Roman permission, the treaty is designed to keep a solvent trading city permanently disarmed and permanently reminded. Carthage in fact offered to pay the balance early in 191 BC and Rome refused, which tells you which of the two functions Rome valued.
Where this leaves the Republic
Rome ended the war in 201 BC as the only great power in the western Mediterranean, holding Spain as well as the islands, with an aristocracy trained by seventeen years of continuous command, a citizen body that had lost a large fraction of its men, and southern Italy in ruins.
It also ended with something less visible and more important: armies that had served together for a decade under the same commanders, and a habit of granting long commands to men who could win with them. Within two years those armies were sent east, against the kingdoms that had inherited Alexander's empire, and Rome acquired in fifty years an empire it had never decided to want. How it governed what it took, and what that did to the constitution, is the next lesson.