The Roman Senate had declared war on Carthage after
Hannibal had attacked, besieged and finally taken the city of
Saguntum in
Iberia in 219 BC. Rome had declared Saguntum an ally but had done nothing to help the city during the eight-month-long siege. Once the siege was over, the combatants started to make ready for the coming struggle, which was to last 18 years.
Roman preparations The Roman navy had been mobilized in 219 BC, fielding 220
quinqueremes for fighting the Illyrians.
Publius Cornelius Scipio received four legions (8,000 Roman and 14,000 allied infantry and 600 Roman and 1,600 allied horse) and was to sail for Iberia escorted by 60 ships. However, Gauls of the Boii and Insubre tribes in northern Italy attacked the Roman colonies of
Placentia and
Cremona, causing the Romans to flee to
Mutina, which the Gauls then besieged. Praetor L. Manlius Vulso marched from
Ariminium with two Roman legions, 600 Roman Horse, 10,000 allied infantry and 1,000 allied cavalry towards
Cisalpine Gaul. This army was ambushed twice on the way, losing 1,200 men. Although the siege of Mutina was raised, the army itself fell under a loose siege a few miles from Mutina. This event prompted the Roman Senate to send one of Scipio's legions and 5,000 allied troops to aid Vulso. Scipio had to raise troops to replace these and thus could not set out for Iberia until September 218 BC. Consul
Tiberius Sempronius Longus received four legions (2 Roman and 2 allied, 8,000 Roman and 16,000 allied infantry and 600 Roman and 1,800 allied horse) and instructions to sail for Africa, escorted by 160 quinqueremes. Sempronius had set sail for
Sicily, where he was to complete his preparations for invading Africa.
Punic preparations Hannibal had dismissed his army to winter quarters after the
Siege of Saguntum. In the summer of 218 BC, Hannibal stationed 15,000 soldiers and 21 elephants in Iberia under his brother
Hasdrubal Barca, and sent 20,000 soldiers in Africa with 4,000 garrisoning Carthage itself. The army that marched for Italy from
Cartagena is supposed to have numbered 90,000 foot and 12,000 cavalry, and 37 elephants. Hannibal divided his army into three columns before crossing the
Ebro River, and attacked the Iberian tribes of Ilergetes, Bergusii and Ausetani in
Catalonia. In a two-month-long campaign, Hannibal subdued parts of Catalonia between the Ebro, the Pyrenees and the Sicoris river in a swift, if costly campaign. The Iberian contingent of the Punic navy, which numbered 50 quinqueremes (only 32 were manned) and 5 triremes, remained in Iberian waters, having shadowed Hannibal's army for some way. Carthage mobilized at least 55 Quinqueremes for immediate raids on Italy. ==Prelude==