Five hundred years had passed, since Julius Cæsar’s first invasion of the Island, when the Romans departed from it for ever. In the course of that time, although they had been the cause of terrible fighting and bloodshed, they had done much to improve the condition of the Britons. They had made great military roads; they had built forts; they had taught them how to dress, and arm themselves, much better than they had ever known how to do before; they had refined the whole British way of living. Agricola had built a great wall of earth, more than seventy miles long, extending from Newcastle to beyond Carlisle, for the purpose of keeping out the Picts and Scots; Hadrian had strengthened it; Severus, finding it much in want of repair, had built it afresh of stone.