Constantius, having eliminated several usurpers in Gaul,…

Emperor Mingyuan launches a major attack on Northern Yan in 418, and puts the Northern Yan capital Helong (in modern Jinzhou, Liaoning) under siege, but is unable to capture Helong and forced to retreat.

The Vandals, following a series of defeats inflicted by the Visigoths, had moved in 417 to the region of present Andalusia, giving the southeastern Spanish province its name.

The Visigoths under Wallia, who had invaded Iberia before receiving lands in Septimania (Southern France), destroy the Siling Vandals and crush the Alans in 418, killing the western Alan king Attaces, the successor of Respendial, who had led the Alans, together with the Vandals and Suebi, on an invasion of the western Roman Empire beginning in 406.

The remainder of his people subsequently appeal to Gunderic, king of the Hasdingi, or Asding Vandals to accept the Alan crown.

Later Vandal kings in North Africa will style themselves Rex Wandalorum et Alanorum ("King of the Vandals and Alans").

The Jews of the Western Roman Empire are excluded from all public offices in 418.

In 418 also, Severus, the bishop of Minorca, claims to have forced five hundred and forty Jews to accept Christianity upon conquering the island.

This first record of Jews on Minorca is also the first case of Jews being forced to choose between conversion and expulsion.

Zosimus, again doubting Pelagius' orthodoxy after renewed investigation at the council of Carthage in 418, reads his commentary on Romans; shocked by its doctrine, he commands Celestius to appear before him for examination.

Celestius flees Rome, thereby appearing self-condemned, and Zosimus issues the Epistola tractoria (“Epistolary Sermon”) that excommunicates Pelagius and Celestius and confirms the council's nine canons condemning their doctrine.

Pelagius, horrified by his excommunication, departs, probably for Egypt; nothing more is known of him after this date.

Even though Zosimus had confirmed Innocent's judgment, he disturbs the African episcopate in a new controversy by espousing the cause of a disreputable priest called Apiarius, who had been excommunicated by Bishop Urbanus of Sicca Veneria.

Defying African canon law, Zosimus dispatches legates to Africa with orders that include reorganizing the method of appeal between Africa and Rome and a threat to excommunicate Urbanus if he does not make amends with Apiarius.

Against the Pope's domination, certain Roman clergy appeal to the imperial court at Ravenna, the capital of the Western Empire, for which act Zosimus excommunicates them.

The case regarding Apiarius remains unsettled when, to the relief of both Africa and Gaul, Zosimus dies on December 26, 418.

When a majority of the Roman electors choose as pope the priest Boniface (believed to have been ordained by Damasus and to have served Innocent at Constantinople), a clerical faction simultaneously chooses his rival Eulalius, a deacon.

The two claims, and the resultant fifth schism, cause chaos in Rome.

The Visigoths’ Settlement in Aquitania

Following the Germanic invasions and internal civil wars, Emperor Honorius rewards his Visigothic federates by granting them land in Aquitania Secunda, a province stretching between the lower Garonne and Loire rivers. This settlement, likely arranged under the hospitalitas system—the Roman practice of billeting soldiers on civilian landowners—provides the Visigoths with a permanent foothold in Gaul.

Centered near Poitou, this territory allows the Visigoths to recover from their long migrations and conflicts, while also serving as a buffer against further barbarian incursions into Roman lands.

The Visigoths as Roman Allies

By 418 CE, Constantius, the powerful Roman general and future co-emperor, formally acknowledges the Visigoths as allies (foederati). In return, they are encouraged to campaign against other barbarian groups—the Vandals, Alans, and Suebi—who had overrun the Iberian Peninsula.

The Birth of the Visigothic Kingdom

While technically still under Roman authority, the Visigothic realm in Gaul operates as a self-governing entity, with its own leadership and internal administration. Though required to provide troops for the empire, the Visigoths effectively establish what will become the Visigothic Kingdom, a political structure that will soon expand beyond Aquitania and play a crucial role in the post-Roman transformation of Western Europe.

The Burgundians, relatively few in number, occupy the lands of the upper Rhone valley.

Serving as foederati, or auxiliaries, in the Roman army, they establish a powerful kingdom that extends to the west bank of the Rhine River.

A fanatical monk named Barsauma of Nisibis gathers a group of like-minded followers in 419 and for the next three years will try to destroy synagogues throughout Palestine.

Some historical sources say that Wallia was related to Alaric only by marriage.

Wallia's daughter marries Rechila, King of the Suevi, and will become the mother of Ricimer and the mother in law of Gundowech, King of the Burgundians.

Wallia is succeeded in 419 as king of the Visigoths by Theodoric, who completes the settlements in Gallia Aquitania and expands his military power to the south.

Galla Placidia bears the second of two children by Constantius in 419, the first being her daughter Justa Grata Honoria (417) and the second Placidus Valentinian (the future emperor Valentinian III).

In this year, Placidia and her husband become involved in the controversy over the election of a new bishop of Rome.

She personally summons the African bishops to a synod in Italy (three of the letters she wrote in the matter survive).

The support of Constantius and Placidia notwithstanding, Eulalius loses the backing of Honorius for violating an agreement that both claimants leave Rome pending a council's decision.

Boniface's reentry into Rome ends the fifteen-week schism.