This study deals with the Roman republican navy from the sixth century to the aftermath of the Third Macedonian War in 167 BC. During this period of time, Rome first extended her power over the ItaIian Peninsula and then in consecutive wars defeated Carthage, Macedon and Syria. The navy played an important role at all stages of the expansion of Rome’s Mediterranean dominion. The Romans could not have achieved what they did without the navy. In this process, the Roman navy itself became the master of Mediterranean after it had participated in the competition for thalassocracy and defeated all the other navies.