Answer:
Expand its territories and facilitate trade.
Step-by-step explanation:
Rome defeated Carthage in the Punic Wars (Carthage) and gained dominance of the western Mediterranean. After getting control over the Mediterranean sea, Romans began to call it as Mare Nostrum (Our Sea).
The Mediterranean Sea was vital to the Roman Empire because it connected to trade with the Middle East and North Africa. By the conquer of the Mediterranean coastline Romans began to establish their territories in Mediterranean islands and onto the east coast (Spain). Rome indicated these new territories as provinces and elected governors to manage them.