The Goths break the peace treaty, renewing their attacks early in 253.

The army is not pleased with the emperor and when Marcus Aemilius Aemilianus, who had replaced Gallus as governor of Moesia Superior and Pannonia, takes the initiative of battle and defeats the Goths in midyear, the soldiers proclaim him emperor.

The Crimean Goths and the Heruls, a Germanic people from northern Europe, dare to venture on the seas beginning in 253, ravaging the shores of the Black Sea in violation of a treaty signed with Rome.

The Goths move south to ravage the Aegean island ports, as well as several mainland Greek towns.

Cornelius, after reigning as Bishop of Rome for two years under Trebonianus Gallus, is exiled by the emperor to Centuricellae (Civitavecchia), where he dies in June 253.

Gallus, preparing for a fight with the usurper Aemilianus, recalls several legions under Licinius Valerianus and orders reinforcements to return to Rome from the Rhine frontier.

Despite these dispositions, Aemilianus marches onto Italy ready to fight for his claim.

Valerian heads south with the northern armies, but Gallus has no chance to face Aemilian in battle: he and Volusian are murdered by their own troops in August 253, in Interamna; these troops then join Aemilianus’ side before his arrival.

The Roman forces of the Upper Rhine declare Valerian emperor a few weeks later and continue their march towards Rome.

Before the two sides come to battle, Aemilianus is assassinated near Spoletium by his troops, who proclaim Valerian emperor.

Despite Aemilianus’ victory over the Goths, his attempt to seize power has allowed the defeated Goths to regroup and invade Greece.

Valerian had arrived too late to save Gallus but he has managed to avenge and succeed him as emperor, proclaimed so by the Raetian soldiers.

Upon his arrival in Rome in September, the Senate quickly acknowledges him, not only for fear of reprisals, but also because he is one of their own.

Recognizing that it is no longer possible for one man to run the vast military operations needed to defend the empire, Valerian in 253 appoints, and the Senate confirms, his thirty-something son Publius Licinius Egnatius Gallienus to rule the West.

The election of one Lucius as Bishop of Rome on, probably June 25, 253, had taken place during the persecution that had caused the banishment of his predecessor Cornelius, and he also had been banished soon after his consecration, but succeeded in gaining permission to return.

He died March 4, 254.

Tradition claims that he was martyred in the persecution of Valerian, but as that is known to have started later than March 254, this seems unlikely.

He is succeeded in May by his archdeacon, who takes the reign name Stephen.

At this time internal disputes racking the Church are as much a threat as the external persecutions.

Following the "Decian persecution" of 250 - 251, churches had split over how to deal with the lapsed, with the strictest approach that of Novatian, later declared a heretic, which has led to further controversy over whether to accept baptism from splinter groups as legitimate sacrament.

In the early part of his pontificate, Stephen is urged by Faustinus, Bishop of Lyon, to take action against Marcian, Bishop of Arles, who has denied communion to the penitent among those whose faith had lapsed during the persecutions, the position called "Novatianism".

Stephen also holds that converts from splinter churches that might be heretical do not need rebaptism, while Bishop Cyprian of Carthage and certain other bishops of the Roman province of Africa hold it necessary for admission to communion.

The Goths, according to Jordanes's Getica, had entered Oium, part of Scythia, under their fifth king, Filimer, where they subdued the Spali (Sarmatians), conquered the Kingdom of the Bosporus and partially destroyed two or three cities on the Euxinean coast, including Olbia and Tyras, where they become divided into the Visigoths ruled by the Balthi family and the Ostrogoths ruled by the Amali family.

Jordanes parses Ostrogoths as "eastern Goths", and Visigoths as "Goths of the western country."

At times, rival kings of some other tribes arise and probably produce some disorganization.

At one of these periods (255), the Goths are able to seize Bosporan shipping and raid the shores of Anatolia.

Mani, born an exceptionally gifted child of Iranian (Parthian) parentage in Babylon, had inherited his father's mystic temperament, and it is said that communications of a supernatural character came to him.

He had first encountered religion in his early youth while living with a Jewish-Christian ascetic group known as the Elcesaites, a subgroup of the Ebionites.

In his mid-twenties, he had come to believe that salvation was possible through education, self-denial, vegetarianism, fasting, and chastity.

He will later claim to be the Paraclete promised in the New Testament, the Last Prophet or Seal of the Prophets, finalizing a succession of men guided by God, which included figures such as Seth, Noah, Abraham, Shem, Nikotheos, Enoch, Zoroaster, Hermes, Plato, Buddha and Jesus.

Mani also follows the Indian holy books, the Puranas and the Kural.

Mani's first excursion had been to the Kushan Empire in northwestern India (several religious paintings in Bamiyan are attributed to him), where he is believed to have lived and taught for some time.

Traveling and preaching throughout the Persian Empire and as far as India, with many disciples to carry out evangelism, he has gathered considerable adherents to his view that the world is irreconcilably divided into the kingdoms of light and darkness, representing good and evil, and that only an abstemious life offers salvation of the soul from the darkness that entraps it.

After forty years of evangelizing, he returns with his retinue to Persia and converts Peroz, King Shapur's brother, to his teaching.

During this period, the large existing religious groups, most notably Christianity and Zoroastrianism, are competing for stronger political and social power.

Although having fewer adherents than Zoroastrianism, for example, Manichaeism wins the support of high ranking political figures and with the aid of the Persian Empire, Mani will initiate several missionary excursions.