After taking over Visigothic kingship from his brother-in-law Alaric, Athaulf took his people over the Western Alps into Gaul, relieving pressure on Italy. Gaul had been denuded of provisions by traveling Burgundians and Vandals. In return for access to grain and regularization of status in the imperial order, Athaulf offered to fight against a Gaulic imperial claimant supported by the Burgundians. Though Honorius accepted the offer and the claimant (Jovianus) fell, a North Africa revolt, lead by yet another imperial claimant, prevented Visigothic access to curtailed supplies, which Honorius monopolized. After taking his people from Provence to Barcelona, Athaulf died (416). His successor Wallia repeated an attempt to cross to North Africa, but failed. By turns intriguing against and negotiating with Honorius, Wallia eventually obtained Visigothic entry into Roman military forces. Shortly thereafter, they annihilated Asding Vandals who had been ravaging Iberia. Honorius' deal appeared to work, and Wallia's people obtained foederati status (now deep within imperial territory), some wheat supplies, and settlement areas in Southwest France, known as Aquitania Secunda. By means of hospitalitas, once used to legally quarter Roman soldiers on farmlands, the Visigoths were made 'guests' of Gaulic landowners, receiving up to 2/3 of the agricultural production. The newcomers lived mostly in the cities. While the indigenous population of Aquitane remained responsible to Roman civil administration, the Visigoths answered only to their own kings, laws, and Arian Christian ecclesiastical authorities. Similar foederati- hospitalitas arrangements were applied to the Suevi and Siling Vandals in Northwestern Gaul, as well as to the Burgundians in the upper Rhone region. All of these tribes theoretically served as Roman forces, and were settled on Germanic 'reservations'. Honorius died in 423, by which time Western Roman lands were in disarray—Italy, Gaul, and segments of Iberia had been severely plundered, Britain had been abandoned, Northern Gaul's allegiances were unreliable, and remaining areas nominally in the empire were beyond effective Roman authority by foederati-hospitalitas. Still, Germans had been kept away from Italy and the Mediterranean shores, so the ancient core of the empire remained pure and preserved.
Honorius' death increased mounting chaos. He had no direct heir, and Eastern Emperor Theodosius II sent an army to fight against a claimant drawing military support from Hunnic mercenaries. Theodosius was able to install Valentinian III (425) on the Western throne. A youth, Valentinian's mother ruled through him; both he and his mother depended on Aetius, the Master of Soldiers in Gaul, of Balkan-Germanic origin. Having lived as an Eastern Roman hostage to the Huns, Aetius was on good terms with them, recruiting them to his forces. As assistant chief of staff of Roman forces in 429, he defeated Burgundians, settling them in Savoy, and restrained the Alans to the Loire Valley. By 433, he was able by murder and pressure to become Master of Soldiers for the entire Western Empire. He focused only on retaining Gaul and Italy. Imperial armies no longer were seen in Spain, British requests went unanswered, and the southern Mediterranean was not guarded.
Upon Honorius' death, the Germanic tribes settled on reserves through hospitalitas left them. Under their new king Theodoric (418-51), the Visigoths moved into cities, such as Toulouse. To prevent further expansion of the Visigoth kingdom, Aetius repeatedly used Hunnic forces. Aetius did not come to terms with the Vandals. In 429 the Vandal leader Gaiseric led his people from north Gaul to Gibraltar, finally securing passage for a Germanic tribe to North Africa. Moving East from Morocco, the Vandals occupied Carthage in 435, meaning that 1) Carthage became an independent German kingdom; 2) because North Africa served as bread basket to the central Roman Empire, wheat and grain supplies for the imperial core were cut back severely; 3) the Vandals obtained a pirate raiding base, used to attack Southern Iberia and Italy for the next thirty years; and 4) a tremendous moral blow was dealt to traditional, Latin Romans, such as the philosopher Augustine, bishop of Hyppo, who wrote the famous City of God; he died while the city suffered Vandal siege.
The failure of Honorius' arrangements to outlast his death resulted as much from the Germanic custom of recognizing a treaty only during the lifetime of its signatories as it was caused by the ill-considered nature of the foederati- hospitalitas arrangements in the first place. Also, disinclination of Germanic federates to respond to Aetius' pleas for assistance when Attila the Hun headed for Italy in 453 showed that their willingness to rally to the imperial standard was limited by the degree to which matters affected their immediate safety. Furthermore, increasingly little could convince the Barbarian latifundians in the process of establishing new kingdoms to abandon their properties. Contemporaneous to the state building enterprises of Barbarians, many areas previously central to Rome's concerns witnessed state- building by Latin rural elites, often of senatorial background, who set up autonomous administrations. Though Roman in form, procedure, self- conception, and stated allegiances, such local principalities were effectively beyond the shrinking Imperial reach. Thus, from the 430s, it was tacit policy to stop caring for these regions. While Aetius repeatedly and unsuccessfully tried to prevent Visigothic expansion, his ultimate lack of access to Hunnic soldiers and sheer inability meant that he, as determiner of official policy, was restricted to concern only for Italy, the primordial core of the Roman state, and small parts of Southeastern France. The need to maintain access to North African food supplies caused him to recognize in some vague manner Vandal occupation of that region. He and subsequent Germanic-Roman military strong-men, such as Ricimer, Orestes, and Odovacar, saw that anything else was beyond their reach, and they concentrated almost exclusively on making and unmaking irrelevant Roman Emperors.