Publius Cornelius Scipio commanded the Roman force sent to stop Hannibal. He did not expect Hannibal to cross the Alps. He expected to fight Hannibal in Spain. With a small army still in Gaul, Scipio tried to stop Hannibal. He moved his army to Italy by sea in time to meet Hannibal. Hannibal made the area behind him safer by defeating the tribe of the Taurini (modern Turin). The opposing forces fought at Carthage. Here, Hannibal forced the Romans to get out of the plain of Lombardy. This victory did much to weaken Roman control over the Gauls. The Gauls decided to join the Carthaginians. Soon all of northern Italy was unofficially allied. Gallic and Ligurian troops soon raised his army back to 40,000 men. Hannibal’s army was ready to invade Italy. Scipio retreated across the River Trebia. He camped at the town of Placentia and waited for more troops. 