Augustus ruled a vast realm. In it all the dreams of world
dominion which Alexander had cherished were more than realized. The empire
included nearly the entire circle of the Mediterranean lands. On the west and
south it found natural barriers in the Atlantic Ocean and the African desert.
On the east the Euphrates River had formed, since the defeat of Crassus,
the dividing line between Rome and Parthia. The northern frontier, beyond which
lay the Germanic barbarians, required, however, additional conquests for its
protection.
THE DANUBE BOUNDARY
The Danube River made an admirable boundary for much of
the Roman territory between the Black Sea and the Rhine. Augustus annexed the
district south of the lower course of this river and formed it into the
province of Moesia (modern Serbia and Bulgaria). The line of the upper Danube
was later secured by the creation of three new provinces on the northern slopes
of the Alps. [4] Henceforth the Balkan peninsula and Italy on the northeast,
where the Alpine passes are low and comparatively easy, were shielded from
attack.
[4] The provinces of Pannonia, Noricum, and Raetia.
