Pelagius, responding in 416 to further attacks from Augustine and Jerome, writes De libero arbitrio (“On Free Will”), which results in the condemnation of his teaching by two African councils.

The Visigoths continue their invasion of Hispania and take control of Tarraconensis.

King Wallia occupies the gold mines at Las Médulas, and forces Jewish citizens to convert to Christianity.

The Visigoths having restored to the Romans the widowed Galla Placidia, the usurper Priscus Attalus, mutilated in Ravenna in 416, is forced to participate in a triumph celebrated by Honorius in the streets of Rome.

After the festivities, …

…Attalus is exiled to the Lipari Islands, north of Sicily.

Jin forces quickly capture Later Qin's major city Luoyang, then head toward the Later Qin capital, Chang'an.

The Later Qin emperor Yao Hong (Yao Xing's son) requests emergency assistance in spring 417.

Emperor Mingyuan summons his council to consider whether to launch armies to try to stop Jin advances to try to save Later Qin.

Most of his advisors, apprehensive at whether Liu Yu actually intends to attack Northern Wei as well, suggest that Emperor Mingyuan try to intercept Liu Yu's forces.

However, Cui Hao opines that this would make Northern Wei the target of Jin attacks; Emperor Mingyuan partially agrees, but still sends some one hundred thousand men, commanded by Baba Song, to guard the northern bank of the Yellow River to prepare for battle.

If a Jin ship is blown by the wind to the northern bank, Northern Wei forces seize the ship and kill or capture its crew, and when Jin forces then land on the northern banks, Northern Wei forces temporarily retreat, then reestablish the northern bank defensive posture as soon as Jin forces reboard their ships.

Angry at this harassment, Liu Yu sends his general Ding Wu to land on the northern bank and deal Northern Wei forces a major defeat.

This ends Emperor Mingyuan's attempts to save Later Qin, and there are no further Jin/Northern Wei battles throughout the campaign as, while Emperor Mingyuan still plans to cut off Liu Yu's path if he is stopped by Later Qin forces, Liu Yu is able to capture Chang'an and destroy Later Qin by fall 417, and Emperor Mingyuan's planned attacks never materialize.

Many former Jin officials who oppose Liu Yu, who had taken refuge with Later Qin, flee to Northern Wei, and Emperor Mingyuan further orders that anyone who can save and deliver members of the Yao imperial clan to Pingcheng will be greatly rewarded.

(How effectively this order was fulfilled is not known; most members of the Yao clan are captured and killed by Liu Yu.)

The anti-Pelagianist views of Augustine, who had begun condemning the doctrine as soon as Pelagius and his followers brought it from Rome to North Africa, begin to prevail over the opposition.

Pelagius settles in Palestine in 415, spending time in Jerusalem.

Pope Innocent in 417 excommunicates him, but Pelagianism continues to draw supporters to his view of divine grace.

Wallia is notably successful in his task, and Honorius extends the area of Visigoth control to include Aquitania and Gallia Narbonensis.

Wallia establishes his capital at Tolosa (modern Toulouse) in 417.

Honorius forces Galla Placidia into marriage, on January 1, 417, to Constantius, who is appointed patricius and becomes a prominent member of the House of Theodosius.

Pope Innocent endorses the condemnations of Pelagius and Celestius and excommunicates them on January 27, 417.

However, Pelagianism continues to draw supporters to Pelagius’ view of divine grace.

Innocent I dies on March 12 after a sixteen-year reign in which he has restored relations between the sees of Rome and Antioch, enforced celibacy of the clergy, and maintained the right of the bishop of Rome to judge appeals from other churches.

The first act of Innocent's successor, Zosimus, is to designate Bishop Patroclus of Arles papal vicar in Gaul, based on an alleged historical primacy of the see of Arles.

This act provokes a crisis affecting all the churches of southern Gaul.

The bishops of Narbonne, Marseille, and Vienne oppose Patroclus' elevation.

Zosimus threatens excommunication.

Simultaneously, Zosimus at first pronounces Pelagius innocent based on his Libellus fidei (“Brief Statement of Faith”), and sends a strongly worded letter to the African bishops on September 21, 417, accusing them of having acted precipitately in their condemnation.