flee to their previously-established colony of Mutina (modern Modena), where they were besieged. A Roman relief force broke through the siege, but was then ambushed and besieged itself. An army had previously been created by the Romans to campaign in Iberia and the Roman Senate detached one Roman and one allied legion from it to send to north Italy. Raising fresh troops to replace these delayed the army's departure for Iberia until September. Meanwhile, Hannibal assembled a Carthaginian army in New Carthage (modern Cartagena) in Iberia and led it northwards along the coast in May or June. It entered Gaul and took an inland route, to avoid the Roman allies to the south. At the battle of the Rhone Crossing Hannibal defeated a force of local Gauls which sought to bar his way. A Roman fleet carrying the Iberian-bound army landed at Rome's ally Massalia (modern Marseille) at the mouth of the Rhone, but Hannibal evaded the Romans and they continued to Iberia. The Carthaginians reached the foot of the Alps by late autumn and crossed them in 15 days, surmounting the difficulties of climate, terrain and the guerrilla tactics of the native tribes. Hannibal arrived with 20,000 infantry, 6,000 cavalry and an unknown number of elephantsthe survivors of the 37 with which he left Iberiain what is now Piedmont, northern Italy in early November; the Romans were still in their winter quarters. His surprise entry into the Italian peninsula led to the cancellation of Rome's planned campaign for the year: an invasion of Africa. Roman defeats, 217–216 BC The Carthaginians captured the chief city of the hostile Taurini (in the area of modern Turin) and seized its food stocks. In late November 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 37,000 men. A large Roman army was lured into combat by Hannibal at the battle of the Trebia, encircled and destroyed. Only 10,000 Romans out of 42,000 were able to cut their way to safety. Gauls now joined Hannibal's army in large numbers. The Romans stationed an army at Arretium and one on the Adriatic coast to block Hannibal's advance into central Italy. In early spring 217BC, the Carthaginians crossed the Apennines unopposed, taking a difficult but unguarded route. Hannibal attempted to