Second Punic War participant Quintus Fabius Maximus Verrucosus
Carthaginian victories, 218–216 BC
Shortly after arriving in Italy the Carthaginians captured the chief city of the hostile Taurini (in the area of modern Turin) and seized its food stocks. In late November 218 BC the Carthaginian cavalry routed the cavalry and light infantry of the Romans at the battle of Ticinus. As a result, most of the Gallic tribes declared for the Carthaginian cause and Hannibal's army grew to more than 40,000 men. The Senate ordered the army in Sicily north to join the force already facing Hannibal, thus abandoning the plan to invade Africa. The combined Roman force under the command of Sempronius was lured into combat by Hannibal on ground of his choosing at the battle of the Trebia. The Carthaginians encircled the Romans and only 10,000 out of 40,000 were able to fight their way to safety. Having secured his position in Cisalpine Gaul by this victory, Hannibal quartered his troops for the winter among the Gauls. The latter joined his army in large numbers, bringing it up to 50,000 men.There was shock when news of the defeat reached Rome, but this calmed once Sempronius arrived, to preside over the consular elections in the usual manner. The consuls-elect recruited further legions, both Roman and from Rome's Latin allies; reinforced Sardinia and Sicily against the possibility of Carthaginian raids or invasion; placed garrisons at Tarentum and other places for similar reasons; built a fleet of 60 quinqueremes; and established supply depots at Ariminum and Arretium in preparation for marching north later in the year. Two armies – of four legions each, two Roman and two allied, but with stronger than usual cavalry contingents – were formed. One was stationed at Arretium and one on the Adriatic coast; they would be able to block Hannibal's possible advance into central Italy and were positioned to move north to operate in Cisalpine Gaul.In early spring 217 BC the Carthaginians crossed the Apennines unopposed, taking a difficult but unguarded route. Hannibal attempted to draw the main Roman army under Gaius Flaminius into a pitched battle by devastating the area they had been sent to protect provoking Flaminius into a hasty pursuit. Hannibal set an ambush and in the battle of Lake Trasimene completely defeated the Roman army, killing 15,000 Romans, including Flaminius, and taking 10,000 prisoners. A cavalry force of 4,000 from the other Roman army was also defeated at the Battle of Umbrian Lake and annihilated. The prisoners were badly treated if they were Romans; captured Latin allies were well treated by the Carthaginians and many were freed and sent back to their cities, in the expectation they would speak well of Carthaginian martial prowess and of their treatment. Hannibal hoped some of these allies could be persuaded to defect.
The Carthaginians continued their march through Etruria, then Umbria, to the Adriatic coast, then turned south into Apulia, hoping to win over some of the ethnic Greek and Italic cities of southern Italy. News of the defeat again caused a panic in Rome. Quintus Fabius Maximus was elected dictator by the Roman Assembly and adopted the "Fabian strategy" of avoiding pitched battles, relying instead on low-level harassment to wear the invader down, until Rome could rebuild its military strength. Hannibal was left largely free to ravage Apulia for the next year. Fabius was unpopular at this period with parts of the Roman army, public and the senate, for avoiding battle while Italy was being devastated by the enemy: there was awareness that his tactics would not lead to a quick end to the war. Hannibal marched through the richest and most fertile provinces of Italy, hoping the devastation would draw Fabius into battle, but Fabius refused. The Roman populace derided Fabius as "the Delayer" (in Latin, Cunctator) and in 216 BC elected new consuls: Gaius Terentius Varro, who advocated pursuing a more aggressive war strategy, and Lucius Aemilius Paullus, who advocated a strategy somewhere between Fabius's and that suggested by Varro.In the spring of 216 BC Hannibal seized the large supply depot at Cannae on the Apulian plain. The Roman Senate authorised the raising of double-sized armies by Varro and Paullus, a force of 86,000 men, the largest in Roman history up to that point. Paullus and Varro marched southward to confront Hannibal and encamped 10 km (6 mi) away. Hannibal accepted battle on the open plain between the armies in the battle of Cannae. The Roman legions forced their way through Hannibal's deliberately weak centre, but Libyan heavy infantry on the wings swung around their advance, menacing their flanks. Hasdrubal Gisco led the Carthaginian cavalry on the left wing and routed the Roman cavalry opposite, then swept around the rear of the Romans to attack their cavalry on the other wing. The heavily outnumbered Carthaginian infantry held out until Hasdrubal charged into the legions from behind. As a result, the Roman infantry was surrounded with no means of escape. At least 67,500 Romans were killed or captured.Miles describes Cannae as "Rome's greatest military disaster". Toni Ñaco del Hoyo describes the Trebia, Lake Trasimene and Cannae as the three "great military calamities" suffered by the Romans in the first three years of the war. Brian Carey writes that these three defeats brought Rome to the brink of collapse. Within a few weeks of Cannae a Roman army of 25,000 was ambushed by Boii Gauls in Cisalpine Gaul at the battle of Silva Litana and annihilated. Fabius became consul in 215 BC and was re-elected in 214 BC.