Valentinian II in the context of "State church of the Roman Empire"

Count Theodosius (Latin: Theodosius comes; died 376), Flavius Theodosius or Theodosius the Elder (Latin: Theodosius major), was a senior military officer serving Valentinian I (r. 364–375) and the Western Roman Empire during Late Antiquity. Under his command the Roman army defeated numerous threats, incursions, and usurpations. Theodosius was patriarch of the imperial Theodosian dynasty (r. 379–457) and father of the emperor Theodosius the Great (r. 379–395).

Appointed comes rei militaris per Britannias (commander of mobile military forces for the Diocese of the Britains) by Valentinian, Theodosius put down the Great Conspiracy (367–368) and the usurpation of Valentinus. After restoring order in Britain he returned to continental Europe and fought against the Alemanni; as Valentinian's magister equitum (Master of Horse) he successfully invaded Alemannic territory (371 or 370). In 372 Theodosius led a successful campaign against the Sarmatians. Within the same year Firmus, a Mauritanian prince, rebelled against Roman rule with the help of African tribes like the Abanni and Caprarienses. Theodosius was sent to Africa and in two hard-fought campaigns (373–374) put down the insurrection. In 376, after the death of emperor Valentinian, he was arrested and executed, presumably as he was seen as a threat to the new western emperors Gratian and Valentinian II.

Gratian (/ˈɡreɪʃiən/; Latin: Gratianus; 18 April 359 – 25 August 383) was emperor of the Western Roman Empire from 367 to 383. The eldest son of Valentinian I, Gratian was raised to the rank of Augustus as a child and inherited the West after his father's death in 375. He nominally shared the government with his infant half-brother Valentinian II, who was also acclaimed emperor in Pannonia on Valentinian's death. The East was ruled by his uncle Valens, who was later succeeded by Theodosius I.

Gratian subsequently led a campaign across the Rhine, attacked the Lentienses, and forced the tribe to surrender. That same year, the eastern emperor Valens was killed fighting the Goths at the Battle of Adrianople, which led to Gratian elevating Theodosius to replace him in 379. Gratian favoured Nicene Christianity over traditional Roman religion, issuing the Edict of Thessalonica, refusing the office of pontifex maximus, and removing the Altar of Victory from the Roman Senate's Curia Julia. The city of Cularo on the Isère river in Roman Gaul was renamed Gratianopolis after him, which later evolved to Grenoble. By 383 Gratian had become unpopular with his army, which abandoned him during a confrontation with the usurper Magnus Maximus near Lutetia (Paris). Gratian fled to Lugdunum and was later murdered.

The Valentinian dynasty, commonly known as the Valentinianic dynasty, was a ruling house of five generations of dynasts, including five Roman emperors during late antiquity, lasting nearly a hundred years from the mid fourth to the mid fifth century. They succeeded the Constantinian dynasty (r. 306–363) and reigned over the Roman Empire from 364 to 392 and from 425 to 455, with an interregnum (392–425), during which the Theodosian dynasty ruled and eventually succeeded them. The Theodosians, who intermarried into the Valentinian house, ruled concurrently in the east after 379.

The Valentinian dynasty's patriarch was Gratianus Funarius, whose sons Valentinian I and Valens were both made Roman emperors in 364. Valentinian I's two sons, Gratian and Valentinian II both became emperors. Valentinian I's daughter Galla married Theodosius the Great, the emperor of the eastern empire, who with his descendants formed the Theodosian dynasty (r. 379–457). In turn, their daughter, Galla Placidia married a later emperor, Constantius III (r. 421–421). Their son, Valentinian III (r. 425–455), who ruled in the west, was the last emperor of the dynasty, whose death marked the end of dynasties in the western empire. During the interregnum, Theodosius' son Honorius ruled in the west, and concurrently with Constantius III in 421. The dynasty has been labelled as Pannonian, based on the family origin in Pannonia Secunda in the western Balkans.

Persecution of pagans in the late Roman Empire began during the reign of Constantine the Great (r. 306–337) in the military colony of Aelia Capitolina (Jerusalem), when he destroyed a pagan temple for the purpose of constructing a Christian church. Rome had periodically confiscated church properties, and Constantine was vigorous in reclaiming them whenever these issues were brought to his attention. Christian historians alleged that Hadrian (2nd century) had constructed a temple to Venus on the site of the crucifixion of Jesus on Golgotha hill in order to suppress Christian veneration there. Constantine used that to justify the temple's destruction, saying he was simply reclaiming the property. Using the vocabulary of reclamation, Constantine acquired several more sites of Christian significance in the Holy Land.

From 313, with the exception of the brief reign of Julian, non-Christians were subject to a variety of hostile and discriminatory imperial laws aimed at suppressing sacrifice and magic and closing any temples that continued their use. The majority of these laws were local, though some were thought to be valid across the whole empire, with some threatening the death penalty, but not resulting in action. None seem to have been effectively applied empire-wide. For example, in 341, Constantine's son Constantius II enacted legislation forbidding pagan sacrifices in Roman Italy. In 356, he issued two more laws forbidding sacrifice and the worship of images, making them capital crimes, as well as ordering the closing of all temples. There is no evidence of the death penalty being carried out for illegal sacrifices before Tiberius Constantine (r. 578–582), and most temples remained open into the reign of Justinian I (r. 527–565). Pagan teachers (who included philosophers) were banned and their license, parrhesia, to instruct others was withdrawn. Parrhesia had been used for a thousand years to denote "freedom of speech." Despite official threats, sporadic mob violence, and confiscations of temple treasures, paganism remained widespread into the early fifth century, continuing in parts of the empire into the seventh century, and into the ninth century in Greece. During the reigns of Gratian, Valentinian II and Theodosius I anti-pagan policies and their penalties increased.

Valentinian I (Latin: Valentinianus; 321 – 17 November 375), sometimes known as Valentinian the Great, was Roman emperor from 364 to 375. He ruled the Western half of the empire, while his brother Valens ruled the East. During his reign, he fought successfully against the Alamanni, Quadi, and Sarmatians, strengthening the border fortifications and conducting campaigns across the Rhine and Danube. Also, his general Theodosius the Elder defeated a revolt in Africa and the Great Conspiracy (a coordinated assault on Roman Britain by Picts, Scoti, and Saxons). Valentinian founded the Valentinian dynasty, with his sons Gratian and Valentinian II succeeding him in the western half of the empire and his daughter Galla marrying emperor Theodosius I.

Magnus Maximus (Classical Latin: [ˈmaːgnus ˈmaːksimus]; died 28 August 388) was Roman emperor in the West from 383 to 388. He usurped the throne from emperor Gratian.

Born in Gallaecia, he served as an officer in Britain under Theodosius the Elder during the Great Conspiracy. In 383, he was proclaimed emperor in Britannia, and in Gaul the next year, while Gratian's brother Valentinian II retained Italy, Pannonia, Hispania, and Africa. In 387, Maximus's ambitions led him to invade Italy, resulting in his defeat by Theodosius I at the Battle of Poetovio in 388. In the view of some historians, his death marked the end of direct imperial presence in Northern Gaul and Britannia.

Quintus Aurelius Symmachus signo Eusebius (/ˈsɪməkəs/, Classical Latin: [ˈsʏmmakʰʊs]; c. 345 – 402) was a Roman statesman, orator, and intellectual. He held the offices of governor of proconsular Africa in 373, urban prefect of Rome in 384 and 385, and consul in 391. Symmachus sought to preserve the traditional religions of Rome at a time when the aristocracy was converting to Christianity, and led an unsuccessful delegation of protest against Emperor Gratian's order to remove the Altar of Victory from the curia, the principal meeting place of the Roman Senate in the Forum Romanum. Two years later he made a famous appeal to Gratian's successor, Valentinian II, in a dispatch that was rebutted by Ambrose, the bishop of Milan. Symmachus's career was temporarily derailed when he supported the short-lived usurper Magnus Maximus, but he was rehabilitated and three years later appointed consul. After the death of Theodosius I, he became an ally of Stilicho, the guardian of Emperor Honorius. In collaboration with Stilicho he was able to restore some of the legislative powers of the Senate. Much of his writing has survived: nine books of letters; a collection of Relationes or official dispatches; and fragments of various orations.