of Cissa. In 217BC 40 Carthaginian and Iberian warships were defeated by 55 Roman and Massalian vessels at the battle of Ebro River, with 29 Carthaginian ships lost. The Romans' lodgement between the Ebro and the Pyrenees blocked the route from Iberia to Italy and greatly hindered the despatch of reinforcements from Iberia to Hannibal. The Carthaginian commander in Iberia, Hannibal's brother Hasdrubal, marched into this area in 215BC, offered battle and was defeated at Dertosa, although both sides suffered heavy casualties. The Carthaginians suffered a wave of defections of local Celtiberian tribes to Rome. The Roman commanders captured Saguntum in 212BC and in 211BC hired 20,000 Celtiberian mercenaries to reinforce their army. Observing that the three Carthaginian armies were deployed apart from each other, the Romans split their forces. This strategy resulted in two separate battles in 211BC, usually referred to jointly as the battle of the Upper Baetis. Both battles ended in complete defeat for the Romans, as Hasdrubal had bribed the Romans' mercenaries to desert. The Romans retreated to their coastal stronghold north of the Ebro, from which the Carthaginians again failed to expel them. Claudius Nero brought over reinforcements in 210BC and stabilised the situation. In 210BC Publius Cornelius Scipio, arrived in Iberia with further Roman reinforcements. In a carefully planned assault in 209BC, he captured Cartago Nova, the lightly-defended centre of Carthaginian power in Iberia. Scipio seized a vast booty of gold, silver and siege artillery, but released the captured population. He also liberated the Iberian hostages who had been held there by the Carthaginians to ensure the loyalty of their tribes. Even so, many of them later fought against the Romans. Roman victory in Iberia, 208–205 BC In the spring of 208BC Hasdrubal moved to engage Scipio at the battle of Baecula. The Carthaginians were defeated, but Hasdrubal was able to withdraw the majority of his army and prevent any Roman pursuit; most of his losses were among his Iberian allies. Scipio was not able to prevent Hasdrubal from leading his depleted army through the western passes of the Pyrenees into Gaul. In 207BC, after recruiting heavily in Gaul, Hasdrubal crossed the Alps into Italy in an attempt to join his brother, Hannibal, but was defeated before he could. In 206BC at the Battle of Ilipa, Scipio with 48,000 men, half Italian and half Iberian, defeated a Carthaginian army of 54,500 men and 32