It is in connection with this invasion that we first hear of the Meats or Mæatæ, who are mentioned by Dion Cassius, or rather his epitomiser Xiphiline, and who are supposed by some to have inhabited the country between the two walls, while others think it more likely that they were a part of the Caledonians, and inhabited the district between the Grampians and the wall of Antonine. We shall not, however, enter into this question here, but endeavour, as briefly as possible, to record all that is known of the remaining transactions of the Romans in the north of Scotland, reserving other matters for the next chapter.
It was not consistent with the policy by which Caracalla was actuated, to continue a war with the Caledonians; for the scene of his ambition lay in Rome, to which he made hasty preparations to depart on the death of his father. He therefore entered into a treaty with the Caledonians by which he gave up the territories surrendered by them to his father, and abandoned the forts erected by him in their fastnesses. The whole country north of the wall of Antonine appears in fact to have been given up to the undisputed possession of the Caledonians, and we hear of no more incursions by them till the reign of the emperor Constantius Chlorus, who came to Britain in the year 306, to repel the Caledonians and other Picts.[17] Their incursions were repelled by the Roman legions under Constantius, and they remained quiet till about the year 345, when they again entered the territories of the provincial Britons; but they were compelled, it is said, again to retreat by Constans, son of Constantine the Great.
Although these successive inroads had been always repelled by the superior power and discipline of the Romans, the Caledonians of the fourth century no longer regarded them in the formidable light in which they had been viewed by their ancestors, and their genius for war improving every time they came in hostile contact with their enemies, they meditated the design of expelling the intruders altogether from the soil of North Britain. The wars which the Romans had to sustain against the Persians in the East, and against the Germans on the frontiers of Gaul, favoured the plan of the Caledonians; and having formed a treaty with the _Scots_, whose name is mentioned for the first time in history in this connection by Ammianus Marcellinus, they, in conjunction with their new allies, about the year 360 invaded the Roman territories and committed many depredations. Julian, who commanded the Roman army on the Rhine, despatched Lupicinus, an able military commander, to defend the province against the Scots and Picts, but he was recalled before he had done much to repel them.