for Sicily was of necessity a naval power and early saw the importance of creating a navy commensurate with its maritime position. The occupation of Tripoli and Tunis by Roger II seized the Mediterranean by the throat; the possession of Corfu threatened the freedom of the Adriatic; but neither conquest was permanent, and in the main the Greek empire and the powers of northern Africa succeeded in keeping the Sicilian kings within their natural boundaries.
In area about four-fifths the size of England, the southern kingdom showed far greater diversity, both in the land and in its inhabitants. Stretching from the sub-tropical gardens of Sicily into the heart of the highest Apennines, it was divided by mountain and sea into distinct natural regions between which communication continues difficult even to-day—the isolated valleys of the Abruzzi, the great plain of Apulia, the 'granite citadel' of Calabria, the rich fields of Campania, the commercial cities of the Bay of Naples and Gulf of Salerno, the contrasted mountains and shore-lands of Sicily itself. The difficulties of geography were increased by differences of race, religion, and political traditions. The mass of the continental population was, of course, of Italian origin, going back in part to the Samnite shepherds of primitive Italy, and while it had been modified in many places by the Lombard conquest, it retained its Latin speech and was subject to the authority of the Latin church. Calabria, however, was
