While Leo reigned in Constantinople, the last act in the drama of the western empire unfolded. In 455 the murderers of Valentinian III put forward as his successor the senior Roman senator, Petronius Maximus, who married Valentinian's widow, Licinia Eudoxia, while her elder daughter Eudocia was offered to his own son Palladius. But Eudocia was already betrothed to Huneric, son of the Vandal king Gaiseric, and the Vandals intervened.40 They plundered Rome for fourteen days, inflicting far greater losses than Alaric's Goths had in 410, thereby earning themselves the reputation which their tribal name preserves today (Procopius, Bell. Vand. 1.5). The emperor was killed and the Vandals took Eudoxia and her two daughters into captivity. In the following years, Gaiseric refused the requests of frequent embassies from Constantinople and from Rome that the imperial women be released, and continued to harass the Italian and Sicilian coastal cities (Priscus fr. 31).
Flavius Ricimer, grandson of Vallia, who had succeeded Athaulph as ruler of the Visigoths between 415 and 418, now made his first appearance, commanding Italy's defenses on behalf of the new Roman ruler, the Gallic senator Flavius Avitus, who was named emperor at Arles in July 455.41 Avitus was soon replaced by Majorian (John of Antioch fr. 202). During his short reign Majorian undertook a campaign in Spain against the Visigoths, then launched an expedition from Spain against the Vandals, who had been preventing the corn ships reaching Rome. On returning to Italy in the summer of 461 he was executed by Ricimer.42 After an interregnum Ricimer nominated another Italian senator, Libius Severus, to be Augustus, who survived until 465.
After Libius Severus' death in 465, Ricimer and the Senate at Rome asked Leo to supply a replacement from Constantinople. The choice fell on Anthemius, grandson of Theodosius II's powerful minister, and he reached Rome in April 467. Ricimer agreed to marry his daughter Alypia. The prospects of stability appeared to have improved now that the ruler was appointed with the eastern emperor's blessing, and he had formed an alliance through marriage with the kingmaker in the West.43 However, the credibility of the regime was damaged by its military failures. Rome gave ground to the Franks, Burgundians, and Visigoths in Gaul, and the combined naval expedition of the eastern and western empires against the Vandals in 468 ended in humiliating failure. Tensions developed after 470 between Anthemius, who was resident at Rome, and Ricimer in Milan, leading to civil war in 472. The combatants divided on ethnic lines, with the civilian population of Rome and the senators taking the side of Anthemius, while the barbarians resident in Italy supported Ricimer. They included the Scirian Odoacar, who was to become king of Italy after the final collapse of the western empire. Rome fell to Ricimer after a five-month siege in July 472. Anthemius was beheaded by Ricimer's nephew, the Burgundian prince Gundobad (John of Antioch fr. 209.1).
Ricimer now appointed the eastern senator Olybrius as Augustus,44 but within weeks both general and emperor had died, each it seems of natural causes. Ricimer's place was assumed by Gundobad, who appointed Glycerius, comes domesticorum, to be emperor. Leo promptly sent his own man, Julius Nepos, a relative by marriage of Zeno's wife Verina, with a force to displace Glycerius. The latter, after a reign of eight months, gave up without a fight, and was allowed to assume the post of bishop of Salona.45
The confusion and weakness of the western rulers had encouraged the ambitions of the barbarians settled in Gaul, the Visigoths under Euric, and the Burgundians under their leader Gundioc. The Burgundians established pacts both with the Gallo-Roman landowners and with the Visigoths to support Arvandus, the praetorian prefect of Gaul from 464 to 469. Arvandus formed a treasonable plot against Anthemius with the Visigothic king Euric.46 The conspiracy was betrayed when leading members of the Gallic provincial council intercepted a letter from Arvandus to Euric:
This seemed to be a document sent to the king of the Goths, urging him not to make peace with the Greek emperor, demonstrating that he ought to launch an attack on the Britanni north of the Loire, stating firmly that the Gallic provinces should be divided with the Burgundians according to the law of the nations, and very many other mad things in the same manner, such as might rouse an aggressive king to fury, a pacific one to shame. (Sidonius, ep. 1.7.5)
Arvandus was reprieved from a death sentence and sent into exile, but the alliance in Gaul disintegrated, with the Burgundians and the Roman population now making common cause against the Visigoths. A final attempt to assert control over Gaul from Italy was made by Nepos, who appointed the Pannonian officer Orestes to take command. In August 475, however, Orestes turned against his emperor. Nepos fled Rome to Dalmatia. Orestes named his own son Romulus to take his place, the last Roman emperor, who was known immediately after his fall in 476 as Augustulus.47 Orestes, however, lost credibility among the barbarian troops on which he relied (Procopius, Bell. Goth. 1.5), and their leader Odoacar assumed control of the western empire.
Gaiseric, the Vandal king, had played a vital role in the unfolding demise of the western empire. He had, by some margin, the longest reign of any of the barbarian rulers, stretching from 428 until his death in 477. The conquest of Africa had forged his people into a formidable force, and they were a major naval as well as a land power. By the capture of Carthage the Vandals became the only barbarian group to exercise lasting control over a major Mediterranean city, and the importance of this was symbolized by the bronze coins struck for Gaiseric, depicting the king on the obverse, between the letters of the legend KARTHAGO.48 The attack on Rome in 455 demonstrated de facto what was already clear, that Italy and the central Mediterranean islands were vulnerable to his naval power. Naval expeditions from Constantinople had twice failed to make an impression on the defenses of Africa, and in 468 a combination of low cunning, good luck, and the use of fire ships enabled him to destroy the largest fleet to appear in the Mediterranean during late antiquity, the 1,100 ships sent by Leo and Anthemius together in 468 (Procopius, Bell. Vand. 3.6.10–27). For both Roman courts this was not only a military but an economic catastrophe, as they had expended more than 64,000 pounds of gold and 700,000 of silver in financing the armada.49
The sea power of the Vandals in the central Mediterranean was the counterpart to the threat posed by the Hunnic forces in Illyricum during the 440s. Both Gaiseric and Attila in the early 450s were on the verge of making marriage alliances with the house of Valentinian III. Both barbarian groups proved capable of deploying their military supremacy to optimum political effect. They received formal embassies from eastern and western Roman emperors alike, and used the threat of their military supremacy to conduct diplomatic business which went far beyond their local or regional interests. The politics of the Roman world between 440 and 480 depended on an elaborate balance of power between the western court based in Rome, the Huns in Illyricum, the eastern emperor at Constantinople, and the Vandals in Carthage.