Construction has begun on the Hexamilion ("six-mile”) wall across the Isthmus of Corinth to guard the only land route into the Peloponnese peninsula from Greece.

The attack of Alaric on Greece in 396 or the sack of Rome in 410 by the Visigoths may have motivated the construction, which includes towers, sea bastions, and at minimum one fortress.

The wall is to constructed with a rubble and mortar core faced with squared stones.

It is not certain how long it took to complete, but the importance given to the task is apparent from the scale of the construction; the Hexamilion is the largest archaeological structure in Greece.

Every structure in the region is cannibalized for stone for the effort, either being incorporated into the wall directly, as is the temple of Poseidon at Isthmia, or being burned into lime, as is the sanctuary of Hera at Perachora as well as much of the ancient statuary of Corinth.

Constantine's fear of an attack from Hispania despite his best efforts comes to pass in 411, when Gerontius advances with the support of his barbarian allies.

By 400 CE, the traditional cremation burials characteristic of Suebi tribes such as the Quadi had disappeared in Bohemia, signaling shifts in cultural and migratory patterns.

In December 409 CE, Hermeric, leader of a Suebi coalition, crossed the frozen Rhine alongside the Vandals and Alans, beginning their migration into Roman Hispania. After crossing the Pyrenees, his group—consisting of Quadi, Marcomanni, and Buri—establishes itself in the Roman province of Gallaecia (modern Galicia and northern Portugal).

The Question of Roman Recognition

The nature of the Suebi’s presence in Iberia remains debated. While Theodor Mommsen argued that they were foederati, and Ernst Stein suggested they had an agreement with the Roman usurper Magnus Maximus, granting them western Iberia, there is no primary evidence of any formal alliance between the Suebi and Rome.

In 411 CE (according to Ludwig Schmidt) or 417 CE (according to Felix Dahn), Hermeric supposedly made a treatywith Emperor Honorius. However, the only recorded event of 411 is the division of Iberia "sorte" (by lot) among the barbarian groups.

As a result of this division:

• The eastern part of Gallaecia, with its capital Bracara Augusta (modern Braga), falls under Suebi control.
• The western portion of the province is allocated to the Hasdingi Vandals, a larger and more populous group.

Pelagius, a Romano-British Christian theologian and biblical interpreter active in Rome, has become the center of a largely aristocratic group whose goal, in contrast to the indifferent morality of other Christians, is to pursue the most rigorous form of the religious life.

He denies the existence of original sin and claims that humans can do what God requires, stressing the independence of the human will and the ability to control one's motives and actions under the guidance of God's law.

Though not a priest, Pelagius is a highly regarded spiritual director for both clergy and laymen.

The rigorous asceticism of his adherents acts as a reproach to the spiritual sloth of many Roman Christians, whose moral standards greatly distress him.

He blames Rome's moral laxity on the doctrine of divine grace that he had heard a bishop cite from the Confessions of Augustine, bishop of Hippo, who in his prayer for continence beseeched God to grant whatever grace the divine will determined.

Pelagius attacked this teaching because it imperiled the entire moral law and soon gained a considerable following at Rome.

His closest collaborator, a lawyer named Celestius, accompanies Pelagius on his move to Africa, like many refugees, after the sack of Rome in 410.

Constantine's position grows even more untenable; his forces facing the rebel Gerontius are defeated at Vienne (411), where his son Constans is captured and executed.

The native African Christian tradition had fallen afoul of the Christian emperors who succeeded Constantine (reigned 305-337) and is reviled as schismatic, branded with the name of Donatism after Donatus, one of its early leaders.

Having broken with the Roman Catholics in 312 over the election of Caecilian as bishop of Carthage, the Donatist oppose state interference in church affairs, and, through the peasant warriors called Circumcellions, promote a program of social revolution combined with eschatological hopes.

Martyrdom following a life of penance is the goal of the religiously minded Donatist.

Though they had formed the majority Christian party in North Africa throughout the last decades of the fourth century, their opponents, now led by Augustine, have gained strength.

Augustine and his chief colleague in the official church, Bishop Aurelius of Carthage, have waged a canny and relentless campaign against Donatism with their books, with their recruitment of support among church leaders, and with careful appeal to Roman officialdom.

In 411, a conference presided over by Augustine's friend the imperial tribune Marcellinus is held in Carthage.

A public debate held in three sessions during June 1-8 and attended by hundreds of bishops on each side ends with a ruling in favor of the official church.

The ensuing legal restrictions on Donatism decide the struggle in favor of Augustine's party.

Constantine's praetorian prefect Decimus Rusticus, who had replaced Apollinaris a year earlier, abandons Constantine, to be caught up in the new rebellion of Jovinus in the Rhineland.

Gerontius traps Constantine inside Arles and besieges him.

Augustine, who is now the leading figure in the North African church, opposes Pelagius’ teachings, condemning the doctrine as soon as Pelagius and his followers bring it from Rome to North Africa.

Augustine argues that no one can control his or her own motivation and that a person requires the assistance of God's grace if he or she is to will and to do good; an individual may overcome the force of sin and live rightly before God only by divine grace.

Ataulf’s first act following his unanimous election to the Visigothic supreme command had been to halt Alaric's southward expansion of the Goths in Italy.

He has led the Goths into Gaul at the instigation of Honorius, who has promised to recognize a Visigothic Kingdom if he defeats the several usurpers who threaten the Roman Empire.

At the same time, a new general has been found to support Honorius.

Constantius, Honorius' Moesian-born magister militum (master of the soldiers), enters Gaul in 411 and, after defeating Gerontius, in turn besieges Constantine in Arles.

Constantine holds out, hoping for the return of his general Edobichus, who is raising troops in northern Gaul among the Franks, but on his return, Edobichus is defeated by a simple stratagem.

Constantine's last slender hope fades when his last troops guarding the Rhine abandon him to support Jovinus.

He takes refuge in a church and is ordained before surrendering to Constantius.

Honorius, the weakest of Roman emperors, has watched from Ravenna as his generals deal with the barbarian invasions and the claims of various usurpers.

Despite the promise of safe passage to Constantine III and his assumption of clerical offices, Constantius imprisons the former soldier in Italy and has him beheaded in either August or September.

His head is sent to Ravenna where it is exhibited from September 18, 411.