Final answer:
The Roman intervention in Sicily, beginning with the First Punic War, was both a defensive action and a step towards further expansion. Rome's subsequent seizure of Corsica and Sardinia after the conflict indicates their intention for external conquests.
Step-by-step explanation:
The Roman intervention in Sicily, which initiated the First Punic War, can be seen as both a defensive action and as a precursor to further external conquests. Polybius suggests that Rome entered the conflict partially for defensive reasons, to prevent Carthage from gaining a stronghold too close to Italy. However, the actions of Rome after securing victory, such as seizing Corsica and Sardinia, indicate an appetite for external conquests beyond mere defense. Thus, one could argue that it was a combination of defending against potential threats and the desire for expansion that drove Roman intervention in Sicily.
Considered in the broader context of Rome's subsequent actions and strategies, as well as their motives for engaging in the conflict—which included the potential riches to be won—suggests that the Sicilian campaign did lay the groundwork for future Roman conquests of the Mediterranean. The Centuriate Assembly's decision to escalate military commitment and the Senate's policies on warfare demonstrate Rome's greater strategic ambitions.