But this very conversion of Macedonia into a province directly
dependent on Rome gave to the relations of Rome with the peoples
on the north-east greater importance, by imposing on the Romans
the obligation of defending the everywhere exposed frontier on
the north and east against the adjacent barbarian tribes; and in
a similar way not long afterwards (621) the acquisition by Rome of
the Thracian Chersonese (peninsula of Gallipoli) previously belonging
to the kingdom of the Attalids devolved on the Romans the obligation
hitherto resting on the kings of Pergamus to protect the Greeks here
against the Thracians.
From the double basis furnished by the valley
of the Po and the province of Macedonia the Romans could now advance
in earnest towards the region of the headwaters of the Rhine and towards
the Danube, and possess themselves of the northern mountains at least
so far as was requisite for the security of the lands to the south.