Hannibal has spent the past two years of his command consolidating his holdings and completing the conquest of Hispania south of the Ebro.
However, Rome, fearing the growing strength of Hannibal in Iberia, makes an alliance with the Hellenized Iberian coastal city of Saguntum, which lies a considerable distance south of the River Ebro and claims the city as its protectorate.
After great tension within the city government, culminating in the assassination of the supporters of Carthage, Hannibal lays siege to the city in 219 BCE.
The city calls in vain for Roman aid, band following a prolonged eight month siege and a bloody struggle, in which Hannibal himself is wounded and the army practically destroyed, the Carthaginians finally take control of the city.
Many of the Saguntians choose to commit suicide rather than face subjugation by the Carthaginians.
Livy reports that it was agreed in the treaty that the Iber should be the boundary between both empires and that the liberty of the Saguntines should be preserved.
Rome demands justice from Carthage.
In view of Hannibal's great popularity, the Carthaginian government does not repudiate Hannibal's actions, and the war he seeks is declared at the end of the year.
Having thus punctuated the long apprenticeship under his father and brother-in-law, Hannibal now determines to carry the war into the heart of Italy by a rapid march through Hispania and southern Gaul.