The siege of Saguntum was a battle which took place in 219 BCE between the Carthaginians and the Saguntines at the town of Saguntum, near the modern town of Sagunto in the province of Valencia, Spain. The battle is mainly remembered today because it triggered one of the most important wars of antiquity, the Second Punic War.

After Hannibal was made supreme commander of Iberia (221 BCE) at the age of 26, he spent two years refining his plans and completing his preparations to secure power in the Mediterranean. The Romans did nothing against him though they received ample warning of Hannibal's preparations. The Romans even went so far as turning their attention to the Illyrians who had begun to revolt. Because of this, the Romans did not react when news reached them that Hannibal was besieging Saguntum. The capture of Saguntum was essential to Hannibal's plan. The city was one of the most fortified in the area and it would have been a poor move to leave such a stronghold in the hands of the enemy. Hannibal was also looking for plunder to pay his mercenaries, who were mostly from Africa and the Iberian Peninsula. Finally, the money could be spent on dealing with his political opponents in Carthage.

After the siege, Hannibal attempted to gain the support of the Carthaginian Senate. The Senate (controlled by a relatively pro-Roman faction led by Hanno the Great) often did not agree with Hannibal's aggressive means of warfare, and never gave complete and unconditional support to him, even when he was on the verge of absolute victory only five miles from Rome. In this episode, however, Hannibal was able to gain limited support which permitted him to move to New Carthage where he gathered his men and informed them of his ambitious intentions. Hannibal briefly undertook a religious pilgrimage before beginning his march toward the Pyrenees, the Alps, and Rome itself.