 Complete the following phrase:  The Roman Republic had been aggressively expanding in the southern Italian mainland for a century before the First Punic War. It had conquered peninsular Italy south of the River Arno by 272 BC, when the Greek cities of southern Italy Magna Graecia submitted at the conclusion of the Pyrrhic War. During this period Carthage, with its capital in what is now Tunisia, had come to dominate southern Spain, much of the coastal regions of North Africa, the Balearic Islands, Corsica, Sardinia, and the western half of Sicily, in a military and commercial empire. Beginning in 480 BC, Carthage had fought a 