In a Pan-Mediterranean “thalassocracy” the ideal seat of imperial government, corresponding to Memphis in the fluvial Egyptiac World, would be one or other of two sites in Sicily – Messina and Marsala – which command respectively the narrower and the wider of the two straits through which the south-eastern and the north-western basins of the Mediterranean communicate with one another. The despots who imposed an imperfect and precarious political unity on the Greek city-states in Sicily and the toe of Italy in the fifth and fourth centuries B.C. […] had never possessed a sufficient surplus of power to enable them to unite the whole Hellenic World, not to speak of the whole circumference of the Mediterranean, round a Sicilian political centre. Syracuse was the capital of a Mediterranean thalassocracy for the first and last time during the residence there of the Roman Emperor Constans II in the years A.D. 663/4-8 […].
But Carthage also commands the wider strait, and the Carthaginians controlled a large part of the Mediterranean. Given the strategic disadvantages of Rome, could the Romans have made more of it after conquering it?
A Study of History, Vol VII, OUP, 1954 (footnote)