Instead of arming the people in their own defence, the emperors recalled all the distant legions, in whom alone they could repose confidence; and collected the whole military force for the defence of the capital and centre of the empire.

The necessity of self-preservation had superseded the ambition of power; and the ancient point of honour never to contract the limits of the empire could no longer be attended to in this desperate extremity.
Britain by its situation was removed from the fury of these barbarous incursions; and being also a remote province, not much valued by the Romans, the legions which defended it were carried over to the protection of Italy and Gaul.

But that province, though secured by the sea against the inroads of the greater tribes of barbarians, found enemies on its frontiers, who took advantage of its present defenceless situation.

The Picts and Scots, who dwelt in the northern parts, beyond the wall of Antoninus, made incursions upon their peaceable and effeminate neighbours; and besides the temporary depredations which they committed, these combined nations threatened the whole province with subjection, or what the inhabitants more dreaded, with plunder and devastation.

The Picts seem to have been a tribe of the native British race, who, having been chased into the northern parts by the conquest of Agricola, had there intermingled with the ancient inhabitants: the Scots were derived from the same Celtic origin, had first been established in Ireland, had migrated to the north-west coasts of this island, and had long been accustomed, as well from their old as their new seats, to infest the Roman province by piracy and rapine [p].