With a population so thinned as it must have been by the heavy drainage made from time to time from the flower of its youth, we can readily conceive how difficult it was to defend the wall which Severus had erected, after the departure of the Romans. But we cannot imagine that the Britons would hesitate to abandon a position which they could no longer maintain, or waste their strength at an outer barrier when the enemy had already marched far into the country. On this point the venerable Gildas must have been misinformed, and the narrative of Zosimus is, beyond doubt, the correct one. From his history it is evident that the Britons rose up and boldly defended themselves from the northern invaders; they also deposed the Roman rulers that still lingered in the British cities, and who, no longer overawed by the dictates of the emperor, doubtless hoped to establish themselves as kings, or chiefs, amongst the different tribes they had so long held in thrall. But the Britons threw off this foreign yoke, and at last rooted out all that remained of the power of Rome. Thus, beside the Picts and Scots, who were ever pouring in their ravaging hordes from the north, and the Saxons, who came with almost every favourable breeze which blew, to the British shore, there was an old and stubborn foe to uproot, and one which had for above four centuries retained a tenacious hold of our island soil. Many of the Romans who remained were in possession of splendid mansions, and large estates, and as the imperial city was now over-run with bands of barbarians, they were loath to leave a land abounding with plenty, for a country then shaken to its very centre by the thunder of war. Though not clearly stated, there is strong reason for believing that these very Romans, who were so reluctant to quit Britain, connived at the ravages of the Picts and Scots, as if hoping, by their aid, once more to establish themselves in the island.