2nd Punic war; The siege of Saguntum

Inevitable war
The Romans noticed the growth of the Carthaginian empire, this time at their west side in Spain. They were aware, that when this empire was big and strong enough, it might reclaim it's lost territories. Very clever they took two measures. They made a treaty with the Carthaginian commander in Spain, successor of Hamilcar (229 bc), Hasdrubal. He was not to cross the Iberus (Ebro) in arms. They hoped this would slow down the Carthaginian development.

Paris's apple
Next Rome used the same trick as they had done in Sicily at the beginning of the first Punic war. They created a bridgehead in Carthaginian territory. With smart diplomacy and promised support against the inclosing Carthaginians, they made Saguntum to be a Roman ally. In doing so they forced Hannibal, who had succeeded Hasdrubal (221 bc), into the action that would give them their just war. Hannibal had to choose between accepting a Roman stronghold in the midst of his territory, where soon the Romans legions would come pouring in and destroying this city as soon as possible. The latter choice meant starting a war he wasn't really ready for. From a strategic point of view he did the right thing, but he had still to convince the government in Carthago.

Legal matters
There has been always a discussion about which of both parties (Romans or Carthaginians) was to blame for the start of the second Punic war. When we forget for a moment this was was inevitable; one of both would have started this war anyhow, we can try and decide who was legally to blame.

Polybius
Polybius the biassed twists and turns until he has "demonstrated" a justum bellum (just war). He digs up old treaties of friendship to "prove" Hannibal had no right to attack Saguntum. In his ardour he forgets these treaties became void at the very moment Rome attacked Carthago on Sicily. The fact that a Carthaginian fleet neared Tarentum and left as soon as they saw Tarentum was in Roman hands cannot be used as an argument for a war 8 years later. Rome may have had the right to enter Sicily, but not the right to attack the Carthaginian forces there. In the piece treaty at the end of the war the old treaties were not renewed, so no one could rely on those anymore. And if not then, the treaties would have been void after the hostile take over of Sardinia and Corsica. So no just war, just a provoked war. Polybius quotes the treaty after the 1st Punic war twice: The first time he doesn't mention anything about the Roman allies, but he does the second time when he is providing excuses for the Romans.
Polybius continues, Hannibal's crossing was another action that wasn't allowed, because of the treaty with Hasdrubal. But that was 6 months after the Roman declaration of war!

Livius
Livius uses another method. He has Hanno, Cathaginian politician and enemy of the Barca's, hold a speech to the Carthaginian senate. He declared the Romans were right and Hannibal should be surrendered to the Romans. As usual this speech came completely from the author's phantasy, since there was no written evidence of such a speech.

Illyrian war
To make things worse, Hannibal took Saguntum at such a speed (8 months), the Romans couldn't interfere any more (Dum Roma conculitur, Saguntum expugnatur= While Rome confers,Saguntum is taken). Their forces were tied up in the second Illyrian war. Once they were available again there was no Saguntum anymore to be protected. So they started a war because they wished to destroy Carthago.