The Emperor Valentinian I. sent to cope with this most dangerous irruption a gallant Spanish officer, Theodosius, entrusting to him large reinforcements of Teutonic mercenaries and two regiments of the Imperial Guard. Theodosius’s first care was to clear the Midlands, a task involving much rapid marching and hard fighting, but successfully carried out. He wisely did not threaten disbanded troops with military punishment, and thus was able to rally the Army of Britain on the corps which accompanied him, and to completely reorganize it. In 369 he cleared the north, and, so Claudian tells us, pursued the enemy oversea to their refuges--presumably the Irish coast and the Hebrides. Whatever exaggeration may be behind the poet’s eulogy, there is no doubt that Theodosius gained great and, for the time, decisive successes. Although the theory of a new ‘province of Valentia’ between the Walls of Hadrian and Antoninus is due to a misunderstanding of the words of Ammianus, there is some reason to think that Theodosius did in a sense advance the border. He abolished the ‘Arcani,’ a sort of frontier intelligence corps composed of border Britons, and this may imply supersession of them by advanced detachments of regulars. Secondly, we find Attacotti soon after serving in considerable numbers in the Roman army, a circumstance which seems to imply complete defeat, if not political subjection. Thirdly, while Ammianus says that Theodosius restored all the frontier forts, excavation appears to indicate that the line of the Wall with its mile-castles was not repaired. The evidence is not quite conclusive, for the remains of the last occupation lying nearest to the surface would be the first to perish. The frontier was guarded in force till forty years later. This has been contested by Mommsen, who suggested that the roll of the Army of Britain in the Notitia Dignitatum was copied from an earlier list in order to hide the chasm caused by the destruction of corps in the Picto-Scottish wars. Professor Oman has satisfactorily rebutted this theory. He points out that, though there is a remarkable survival of old regiments, yet intermingled with them are many with unquestionable fourth-century titles such as ‘The Thundering Moors,’ ‘The Senior Lions,’ and ‘The Bears of Valentinian.’ Claudian distinctly states that to meet Alaric, Stilicho withdrew troops from the North of Britain. Coins of Maximus (383-388) have been found on the Wall, proving an occupation until almost the end of the fourth century; and lacking, as there is, information of any great disaster, it cannot be asserted that the Roman hold on Britain was not effective until the last. The case of the Attacotti is suggestive, and there is evidence (some of it certainly late) that the British tribes between the walls were practically adjuncts of the province and co-operating in its defence.