What is known is Carthage under Hannibal did lay siege to the town for eight long and deadly months. The citizens of Saguntum pleaded with Rome for help. Rome dispatched ambassadors to first plead with Hannibal to stop his siege. He refused and then sent his agents back to Carthage to ensure they supported him. Next Rome sent a delegation to Carthage and demanded they stop Hannibal. This laid the stage for a most dramatic scene.
When the Carthaginians finally stopped talking, one of the Roman senators walked forward to the assembly, gathering up the folds of his toga as he went. When he stopped to address them, it looked as if he was carrying something in those folds - and indeed he was. With a calm and steady voice he said, "Here we bring you both war and peace. Take whichever you wish." A shout rose up in the council. These oligarchs of Carthage were not used to having ultimatums flung at them. They angrily told the Romans to leave whichever they wished. And so the Roman senator let drop the folds of his toga saying, "Then I leave you war." The Carthaginians accepted the gift. - pg 103-104, Empires of Trust.
Thus the Second Punic War started. Saguntum's walls were finally breached after eight months. and Rome had not come to their aide. Instead many people in that destroyed city, after Hannibal demanded their surrender, destroyed their treasures and killed themselves.
Next spring would bring Hannibal across the Alps and into Italy where for 17 years he would run wild in the hinterlands. The Romans, even as allies deserted them and the defeat at Cannae, hung on. One of Hannibal's most effective weapons on splitting up Rome's allies was Rome's failure to support Saguntum. The Roman generals launched attacks into Spain and managed to cut off Hannibal's supply lines which further slowed down his rampage. Then the Republic was blessed with a new general, Publius Scipio, who invaded North Africa and took the war to Carthage's doorstep. This made Carthage recall Hannibal to defend the homeland. And Scipio defeated Hannibal and forced a new treaty upon the Carthaginians, henceforth they would lose Spain and content themselves with their capitol. Thus ended the Second Punic War.
Just something to think about as people try to compare everything happening now with things that only happened 60 years ago. There are far more examples than that to study and learn lessons from.