What significant issue gave cause to the Second Punic War?

Answer 1

In 237 BCE Rome took the excuse of a revolt by mercenaries to seize control of Corsica and Sardinia in breach of the treaty which ended the First Punic War with Carthage.

Carthage began to conquer Spain over the next seven years, but signed a treaty with Rome in 226 BCE not to go north of the Ebro River.

In 220 BCE the Cartaginians captured Saguntum, which was within the Ebro limit, but Rome used this as an excuse to declare war to confront an increasingly confident and expansionary Carthage.

Answer 2

The Second Punic War began in 218 BC. The main issue between Rome and Carthage was Spain. Carthage's power there rested on the leadership of the Phoenician colonies there which controlled the interior areas of Spain. The Iberian peninsula was a source for mercenaries to protect Carthage's interests. Spain was very valuable as it had gold and silver. The forests there were also a source of wood to build their fleets.Apparently Rome and Carthage were having diplomatic problems with each other. Rome had been placing pressure on Carthage to ease up its continued growth and power in Spain. This was hardly something that Carthage believed was their business and not an issue that Rome needed to be concerned with. Not the case as far as Rome was concerned. Ancient records are not exact, however, sources say that a treaty of sorts was worked out wherein Carthage agreed to slow down its growth in Spain. Two things can be said with some authority based on the fact that Carthage was a powerful actor in the Eastern Mediterranean Sea. 1) Carthage was a threat to Rome ; and 2) Spain's riches were denied to Rome as long as Carthage controlled it.

When Hannibal assaulted a city in Spain that claimed it was under Rome's protection, Rome was only to glad to help them out. The city was captured by Hannibal and Rome decided to declare war and settle the "Iberian" problem with force rather than diplomacy.