The main secret of the success of the emperors of the fifth century in holding their own came from the fact that they had reorganized their armies, and filled them up with native troops in great numbers. Leo I. was the first ruler who utilized the military virtues of the Isaurians, or mountain populations of Southern Asia Minor. He added several regiments of them to the army of the East, but it was his son-in-law and successor, Zeno, himself an Isaurian born, who developed the scheme. He raised an imperial guard from his countrymen, and enlisted as many corps of them as could be raised; moreover, he formed regiments of Armenians and other inhabitants of the Roman frontier of the East, and handed over to his successor, Anastasius, an army in which the barbarian auxiliaries—now composed of Teutons and Huns in about equal numbers—were decidedly dominated by the native elements. The last danger which the Eastern Empire was to experience from the hands of the Germans fell into the reign of Zeno. The Ostrogoths had submitted to the Huns ninety years before, when their brethren the Visigoths fled into Roman territory, in the reign of Valens. But when the Hunnish Empire broke up at the death of Attila [A.D. 452], the Ostrogoths freed themselves, and replaced their late masters as the main danger on the Danube. The bulk of them streamed south-westward, and settled in Pannonia, the border-province of the Western Empire, on the frontier of the East-Roman districts of Dacia and Moesia. They soon fell out with Zeno, and two Ostrogothic chiefs, Theodoric, the son of Theodemir, and Theodoric, the son of Triarius, were the scourges of the Balkan Peninsula for more than twenty years. While the bulk of their tribesmen settled down on the banks of the Save and Mid-Danube, the two Theodorics harried the whole of Macedonia and Moesia by never-ending raids. Zeno tried to turn them against each other, offering first to the one, then to the other, the title of _Magister militum_, and a large pension. But now—as in the time of Alaric and Stilicho—it was seen that “dog will not eat dog”; the two Theodorics, after quarrelling for a while, banded themselves together against Zeno. The story of their reconciliation is curious.