Before Hannibal, Rome had never faced an enemy so determined to bring about its total destruction, and the resultant level of mobilisation was unprecedented in its history. The fall of Saguntum and subsequent crossing of the River Iber had a profound effect on the Romans; they immediately prepared for war, levying additional Legions and building up their navy. Forces were sent to guard Sicily; as the principle theatre during their first war with Carthage, the Romans assumed the Carthaginians would try to regain control of the island. This also enabled them to strike at Carthage itself. Further Legions were raised and sent to check Hannibal's progress through Iberia, and were surprised to discover he had already entered Gaul by the time they reached their allies in Massilia, on the Rhone. After failing to engage Hannibal's army, which had headed north towards the foot of the Alps, most of the Roman army continued on into Iberia, hoping to undermine the remaining Barcid presence there.
