Honorius died in 423, and was succeeded by Valentinian III.  His long reign was marked by a series of disasters, which foretold the rapidly approaching dissolution of the western empire.

Genseric, king of the Vandals, in 429 crossed into Africa, conquered the province, and set up in the depopulated territory, with Carthage as his capital, a new rule and government.  Italy was filled with fugitives from Africa, and a barbarian race, which had issued from the frozen regions of the north, established their victorious reign over one of the fairest provinces of the empire.  Two years later, in 441, a new and even more terrible danger threatened the empire.

The Goths and Vandals, flying before the Huns, had oppressed the western World.  The hordes of these barbarians, now gathering strength in their union under their king, Attila, threatened an attack upon the eastern empire.  In appearance their chieftain was terrible in the extreme; his portrait exhibits the genuine deformity of a modern Calmuck:  a large head, a swarthy complexion, small, deep-seated eyes, a flat nose, a few hairs in the place of a beard, broad shoulders, and a short, square body of nervous strength, though of a disproportionate form.  He had a custom of fiercely rolling his eyes, as if he wished to enjoy the terror which he inspired.

This savage hero, who had subdued Germany and Scythia, and almost exterminated the Burgundians of the Rhine, and had conquered Scandinavia, was able to bring into the field 700,000 barbarians.  An unsuccessful raid into Persia induced him to turn his attention to the eastern empire, and the enervated troops of Theodosius the Younger dissolved before the fury of his onset.  He ravaged up to the very gates of Constantinople, and only a humiliating treaty preserved his dominion to the “invincible Augustus” of the East.

After the death of Theodosius the Younger, and the accession of Marcian, the husband of Pulcheria, Attila threatened, in 450, both empires.  An incursion of his hordes into Gaul was rendered abortive by the conduct of the patrician, AEtius, who, uniting all the various troops of Gaul and Germany, the Saxons, the Burgundians, the Franks, under their Merovingian prince, and the Visigoths under their king, Theodoric, after two important battles, induced the Huns to retreat from the field of Chalons.  Attila, diverted from his purpose, turned into Italy, and the citizens of the various towns fled before the savage destroyer.  Many families of Aquileia, Padua, and the adjacent towns, found a safe refuge in the neighbouring islands of the Adriatic, where their place of refuge evolved, in time, into the famous Republic of Venice.