During the life-time of Constantine, Britain partook of the civil tranquillity of the rest of the world; but in the reign of his immediate successors, the Picts and Scots renewed their incursions into the lower province. This was not the only evil which Roman Britain had to endure. Magnentius, a native of the isle, entered into a contest with Constantius II. for the empire of the world, and in support of his claims, collected an army, (chiefly drawn from Britain) with which he three times met his foe. On the death of Magnentius, by his own hands, in the year 353, his successful rival inflicted a bloody revenge upon the Britons for having supported their countryman: meanwhile the Picts and Scots harassed them, on the north, with redoubled fury. [Sidenote: THEODOSIUS REPAIRS THE WALL.] Little is recorded of Britain in the reign of Julian the Apostate. In the time of Jovian his successor, the Picts, Saxons, and Scots, vexed it by increasing calamities. Valentinian obtained the purple A.D. 364, when the state of the country was so alarming as to require immediate attention. Even London seems to have been menaced by the enemy, if it was not actually in their hands. Theodosius, the ablest general of his time, went to the assistance of the Britons, drove the enemy before him, and recovered the provincial cities and forts. He then repaired the cities and _prætenturæ_ and erected some new forts. Horsley thinks that the Wall in the North of England, and the stations upon it, are the _prætenturæ_ referred to. Valentinian, having, in 367, united with himself in the government of the empire, Gratian his son, died, A.D. 375. Six days afterwards, his second son, Valentinian II. was proclaimed his successor. The two brothers reigned together, Theodosius the Great presiding at the same time in the Eastern provinces, until Gratian was killed A.D. 383. Four years afterwards, Valentinian was robbed of the purple by Maximus, but applied for assistance to his eastern colleague, Theodosius, and once more entered Rome with imperial dignity. The sovereignty of Britain, Gaul, and Spain was, however, still conceded, for the present, to Maximus, who adopted Treves as the seat of his government. [Sidenote: THE ISLAND DRAINED OF ITS YOUTH.] In this struggle Britain suffered severely. Maximus, having served in the island under the elder Theodosius, was a favourite with the Romanized Britons. They flocked to his standard in such numbers that the island seemed drained of its youth. More than a hundred thousand persons are said to have accompanied him from Britain to the continent.