At the beginning of the fifth century the eastern half of the Empire had seemed no less likely than the western to fall under the dominion of the barbarian, and crumble to pieces. The Goths were cantoned all over Thrace, Moesia, and Asia Minor, and the Gothic general Gainas had taken possession of the person and authority of the Emperor Arcadius. Had he been a man of greater ability he might have made and unmade emperors, as Ricimer afterwards did in the West. But the schemes of Gainas were wrecked, and the Empire saved by the great riot at Constantinople in 401, when the Gothic _foederati_ were massacred, and their leader chased away by the infuriated populace, who thus saved not only their own homes, but the whole East, from the danger of Gothic domination. Though the European provinces of the Eastern Empire suffered grievously from Teutonic ravages during the first eighty years of the century, there was never again any danger that the barbarians would get hold of the machinery of government, and subvert the Empire from within. In the long reign of Theodosius II. (406-450), if no progress was made in strengthening the realm, at least no ground was lost. Two external causes were, during this time, operating in favour of the Eastern Empire. The first was the absolute impregnability of Constantinople against any invader who could only assault it from the land side: the town could not be starved out,—as Rome was starved by Alaric,—and its walls could laugh to scorn all such siege appliances as that age knew. Though Goth and Hun pushed their ravages far and wide in the Balkan peninsula, they never seriously attempted to molest the great central place of arms on which the East-Roman power based itself. [Sidenote: Importance of Constantinople.] The Western Empire had no such stronghold—capital, arsenal, harbour, and centre of commerce all in one. Ravenna, where the Western Caesars took refuge in times of storm and stress, was in every way inferior to Constantinople as a base of armed resistance to the invader. Though its marshes made it strong, it did not cover or protect any considerable tract of country, and it was just far enough from its harbour to allow of an enemy cutting off its supplies.