When Rome had completed the organisation of her power round the Mediterranean, there followed a long transitional epoch, during which the oceanic development of Western civilisation was gradually preparing. The transition began with the Roman road system, constructed for the greater mobility of the marching legions. After the close of the Punic Wars four Latin-speaking provinces encircled the Western Mediterranean—Italy, Southern Gaul, Eastern and Southern Spain, and Carthaginian Africa. The outer boundary of the African province was protected by the Sahara Desert, and Italy had in rear the Adriatic moat, but in Gaul and Spain Rome found herself the uncomfortable neighbour of independent Celtic tribes. Thus the familiar dilemma of Empire presented itself; to advance and end the menace, or to entrench and shut it out, but leave it in being. A still virile people chose the former course, and the frontier and the roads were carried through to the ocean along a thousand miles of frontage between Cape St. Vincent and the mouths of the Rhine. As a consequence the Latin portion of the Empire came to be based on two features of Physical Geography: on the one hand was the Latin Sea—the Western Mediterranean; and on the other hand was the
