CHAPTER XIV.

ROMAN FRONTIER DEFENCES AND ROADS,

Natural Limits of the Roman Empire— Frontier Defences— Chiefly organised
by Hadrian— The Ptriplus of Arrian— Dio's Account of Hadrian's
System— The German Limes— Chains of Military Posts— Defences of
the Upper Euphrates— The Roman Roads— The Via Aurelia— Via
Aemilia Scauri— Via Julia— Road through Southern Gaul and Spain—
The Via Flaminia— Via Aemilia— Passes of the Alpes Cottiae, Graiae,
and Penninae— Roman Roads in Gaul, and in Britain— Watling Street—
Fosse ^ Way— Ermine Street— Icknield Street -Passes of the Alpes
Rhaeticae and Juliae— Road through Pannonia to Byzantium— The via
Appia— The Via Egnatia— Main Roads through Asia and Africa— Roman
Itineraries— The Antonine Itinerary— Its Probable Date— Not a com-
pletely Homogeneous Document— Its Contents— The Itinerarium Mari-
timum— The Jerusalem Itinerary— The Peutinger Table— Its Transcrip-
tion, and probable Date of Composition.

THE reign of Hadrian, at which we have now arrived, affords
a suitable opportunity for surveying the boundaries

Natural

of the Roman empire when it had reached its Limits of the

utmost limits, and the defences by which it was
protected. The limits which, as Gibbon remarks,
appeared to have been permanently placed for that purpose by
nature, were on the west the Atlantic Ocean; the Rhine and
Danube on the north ; the Euphrates on the east ; and towards
the south the sandy deserts of Arabia and Africa1. These
boundaries were recommended by Augustus to his successors j
and they were observed by subsequent emperors, except in
Britain, and in two districts into which Trajan carried his
victorious arms— Mesopotamia, which for a short time, and
Dacia, which for a longer period, became subject to Rome.
It was ohly by gradual stages, however, that a
system of frontier defence grew up along these lines.
In some instances a belt of allied native states,
1 Dtdmeond Fatt^ vol. I p. 139, ed. Smith.