th his rule. He completed
the conquest of the country afterwards known as Wales, and thereby
pushed the western frontier of Roman Britain to the sea. Yet from the
fact that he found it necessary still to leave garrisons at Deva and
Isca Silurum, it may be gathered that the tribes occupying the hill
country were not so thoroughly subdued as to cease to be dangerous.
Although the idea entertained by Ostorius of making a frontier on land
towards the west had thus been abandoned, it was still necessary to
provide a frontier towards the north. Even before Agricola arrived it
had been shown to be impossible to stop at the line between the Mersey
and the Humber. Beyond that line was the territory of the Brigantes,
who had for some time occupied the position which in the first years
of the Roman conquest had been occupied by the Iceni--that is to say,
they were in friendly dependence upon Rome, without being actually
controlled by Roman authority. Before Agricola's coming disputes had
arisen with them, and Roman soldiers had occupied their territory.
Agricola finished the work of conquest. He now governed the whole of
the country as far north as to the Solway and the Tyne, and he made
Eboracum, the name of which changed in course of time into York, the
centre of Roman power in the northern districts. A garrison was
established there to watch for any danger which might come from the
extreme north, as the garrisons of Deva and Isca Silurum watched for
dangers which might come from the west.

23. =Agricola's Conquests in the North.=--Agricola thought that there
would be no real peace unless the whole island was subdued. For seven
years he carried on warfare with this object before him. He had
comparatively little difficulty in reducing to obedience the country
south of the narrow isthmus which separates the estuary of the Clyde
from the estuary of the Forth. Before proceeding further he drew a
line of forts across that isthmus to guard the conquered country from
attack during his absence. He then made his way to the Tay, but he had
not marched far up the valley of that river before he reached the edge
of the Highlands. The Caledonians, as the Romans then called the
inhabitants of those northern regions, were a savage race, and the
mountains in the recesses of which they dwelt were rugged and
inaccessible, offering but little means of support to a Roman army. In
=84= the Caledonians, who, like all barbarians when they first come in