Probus endeavored to weaken the power of the Germans, by separating and colonizing them, wherever it was possible. One of his experiments, however, had a very different result from what he expected. He transported a large number of Frank captives to the shore of the Black Sea; but, instead of quietly settling there, they got possession of some vessels, soon formed a large fleet, sailed into the Mediterranean, plundered the coasts of Asia Minor, Greece and Sicily, where they even captured the city of Syracuse, and at last, after many losses and marvellous adventures, made their way by sea to their homes on the Lower Rhine. Towards the close of the third century, Constantine, during the reign of his father, Constantius, suppressed an insurrection of the Franks, and even for a time drove them from their islands on the coast of Holland. He afterward crossed the Rhine, but found it expedient not to attempt an expedition into the interior. He appears to have had no war with the Alemanni, but he founded the city of Constance, on the lake of the same name, for the purpose of keeping them in check. The boundaries between Germany and Rome still remained the Rhine and the Danube, but on the east they were extended to the Black Sea, and in place of the invasions of Cæsar, Drusus and Germanicus, the Empire was obliged to be content when it succeeded in repelling the invasions made upon its own soil. Three hundred years of very slow, but healthy growth on the one side, and of luxury, corruption and despotism on the other, had thus changed the relative position of the two races. CHAPTER V. THE RISE AND MIGRATIONS OF THE GOTHS. (300--412.) Rise of the Goths. --German Invasions of Gaul. --Victories of Julian. --The Ostrogoths and Visigoths. --Bishop Ulfila. --The Gothic Language. --The Gothic King, Athanaric. --The Coming of the Huns. --Death of Hermanric. --The Goths take refuge in Thrace. --Their Revolt. --Defeat of Valens. --The Goths under Theodosius. --The Franks and Goths meet in Battle. --Alaric, the Visigoth. --He invades Greece. --Battle with Stilicho. --Alaric besieges Rome. --He enters Rome, A. D. 410. --His Death and Burial. --Succession of Ataulf. --The Visigoths settle in Southern Gaul. --Beginning of other Migrations. [Sidenote: 325. RISE OF THE GOTHS.] Rome, as the representative of the civilization of the world, and, after the year 313, as the political power which left Christianity free to overthrow the ancient religions, is still the central point of historical interest during the greater part of the fourth century. Until the death of the Emperor Valentinian, in 375, the ancient boundaries of the Empire, though frequently broken down, were continually re-established, and the laws and institutions of the Romans had prevailed so long throughout the great extent of conquered territory that the inhabitants now knew no other.