These tribes, finding their more opulent neighbours exposed to invasion, soon broke over the Roman wall, no longer defended by the Roman arms; and, though a contemptible enemy in themselves, met with no resistance from the unwarlike inhabitants.
The Britons, accustomed to have recourse to the emperors for defence as well as government, made supplications to Rome; and one legion was sent over for their protection.

This force was an overmatch for the barbarians, repelled their invasion, routed them in every engagement, and having chased them into their ancient limits, returned in triumph to the defence of the southern provinces of the empire [q].

Their retreat brought on a new invasion of the enemy.

The Britons made again an application to Rome, and again obtained the assistance of a legion, which proved effectual for their relief: but the Romans, reduced to extremities at home, and fatigued with those distant expeditions, informed the Britons that they must no longer look to them for succour, exhorted them to arm in their own defence, and urged that, as they were now their own masters, it became them to protect by their valour that independence which their ancient lords had conferred upon them [r].

That they might leave the island with the better grace, the Romans assisted them in erecting anew the wall of Severus, which was built entirely of stone, and which the Britons had not at that time artificers skilful enough to repair [s].