Gratian in the context of "Battle of Adrianople"

Theodosius I (Ancient Greek: Θεοδόσιος Theodosios; 11 January 347 – 17 January 395), also known as Theodosius the Great, was Roman emperor from 379 to 395. He won two civil wars and was instrumental in establishing the Nicene Creed as the orthodox doctrine for Nicene Christianity. Theodosius was the last emperor to rule the entire Roman Empire before its administration was permanently split between the Western Roman Empire and the Eastern Roman Empire. He ended the Gothic War (376–382), but did so on terms disadvantageous to the empire, with the Goths remaining and politically autonomous within Roman territory, albeit as nominal allies.

Born in Hispania, Theodosius was the son of a high-ranking general of the same name, Theodosius the Elder, under whose guidance he rose through the ranks of the Roman army. Theodosius held independent command in Moesia in 374, where he had some success against the invading Sarmatians. Not long afterwards, he was forced into retirement, and his father was executed under obscure circumstances. Theodosius soon regained his position following a series of intrigues and executions at Emperor Gratian's court. In 379, after the eastern Roman emperor Valens was killed at the Battle of Adrianople against the Goths, Gratian appointed Theodosius as a successor with orders to take charge of the military emergency. The new emperor's resources and depleted armies were not sufficient to drive the invaders out; in 382 the Goths were allowed to settle south of the Danube as autonomous allies of the empire. In 386, Theodosius signed a treaty with the Sasanian Empire which partitioned the long-disputed Kingdom of Armenia and secured a durable peace between the two powers.

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.

Valens (/ˈveɪlənz/; Ancient Greek: Ουάλης, romanized: Ouálēs; 328 – 9 August 378) was Roman emperor from 364 to 378. Following a largely unremarkable military career, he was named co-emperor by his elder brother Valentinian I, who gave him the eastern half of the Roman Empire to rule. In 378, Valens was defeated and killed at the Battle of Adrianople against the invading Goths, which astonished contemporaries and marked the beginning of barbarian encroachment into Roman territory.

As emperor, Valens continually faced threats both internal and external. He defeated, after some dithering, the usurper Procopius in 366, and campaigned against the Goths across the Danube in 367 and 369. In the following years, Valens focused on the eastern frontier, where he faced the perennial threat of Persia, particularly in Armenia, as well as additional conflicts with the Saracens and Isaurians. Domestically, he inaugurated the Aqueduct of Valens in Constantinople, which was longer than all the aqueducts of Rome. In 376–77, the Gothic War broke out, following a mismanaged attempt to settle the Goths in the Balkans. Valens returned from the east to fight the Goths in person, but lack of coordination with his nephew, the western emperor Gratian (Valentinian I's son), as well as poor battle tactics, led to Valens and much of the eastern Roman army dying in a battle near Adrianople in 378.

In the year before the First Council of Constantinople in 381, Nicene Christianity became the official religion of the Roman Empire when Theodosius I, emperor of the East, Gratian, emperor of the West, and Gratian's junior co-ruler Valentinian II issued the Edict of Thessalonica in 380, which recognized the catholic orthodoxy, as defined by the Council of Nicea, as the Roman Empire's state religion. Historians refer to this state-sponsored church using a variety of terms: the catholic church, the orthodox church, the imperial church, the Roman church, or the Byzantine church, with some also used for wider communions extending beyond the Roman Empire. The Eastern Orthodox Church, Oriental Orthodoxy, and the Catholic Church all claim to stand in continuity from the Nicene Christian church to which Theodosius granted recognition. Political differences between the Eastern Roman Empire and the Persian Sassanid Empire led to the separation of the Church of the East in 424. A doctrinal split within the imperial church led to the independence of early Oriental Orthodoxy, while the fall of the Western Roman Empire initiated the gradual separation between Eastern and Western Christianity, culminating in the East-West schism of 1054. The Western Church evolved into the Latin Catholic Church while the Eastern Church that remained under the patronage of the Eastern empire and evolved into the Greek Orthodox Church.

Earlier in the 4th century, following the Diocletianic Persecution of 303–313 and the Donatist controversy that arose in consequence, Constantine the Great had convened councils of bishops to define the orthodoxy of the Christian faith and to expand on earlier Christian councils. A series of ecumenical councils convened by successive Roman emperors met during the 4th and the 5th centuries, but Christianity continued to suffer rifts and schisms surrounding the theological and christological doctrines of Arianism, Nestorianism, Miaphysitism, and Dyophysitism. In the 5th century, the Western Roman Empire decayed as a polity; invaders sacked Rome in 410 and in 455, and Odoacer, an Arian barbarian warlord, forced Romulus Augustus, the last nominal Western Emperor, to abdicate in 476. However, apart from the aforementioned schisms, the church as an institution persisted in communion, if not without tension, between the East and West. In the 6th century, the Byzantine armies of the Byzantine Emperor Justinian I recovered Italy and other regions of the Western Mediterranean shore. The Byzantine Empire soon lost most of these gains, but it held Rome, as part of the Exarchate of Ravenna, until 751, a period known in church history as the Byzantine Papacy. The early Muslim conquests of the 7th–9th centuries would begin a process of converting most of the then-Christian world in the Levant, Middle East, North Africa, regions of Southern Italy and the Iberian Peninsula to Islam, severely restricting the reach both of the Byzantine Empire and of its church. Christian missionary activity directed from the capital of Constantinople did not lead to a lasting expansion of the formal link between the church and the Byzantine emperor, since areas outside the Byzantine Empire's political and military control set up their own distinct churches, as in the case of Bulgaria in 919.

Normandy was a province in the North-West of what later became France under the Ancien Régime which lasted until the later part of the 18th century. Initially populated by Celtic tribes in the West and Belgic tribes in the North East, it was conquered in AD 98 by the Romans and integrated into the province of Gallia Lugdunensis by Augustus. In the 4th century, Gratian divided the province into the civitates that constitute the historical borders. After the fall of Rome in the 5th century, the Franks became the dominant ethnic group in the area and built several monasteries. Towards the end of the 9th century, Viking raids devastated the region, prompting the establishment of the Duchy of Normandy in 911. After 150 years of expansion, the borders of Normandy reached relative stability. These old borders roughly correspond to the present borders of Lower Normandy, Upper Normandy and the Channel Islands. Mainland Normandy was integrated into the Kingdom of France in 1204. The region was badly damaged during the Hundred Years War and the Wars of Religion, the Normans having more converts to Protestantism than other peoples of France. In the 20th century, D-Day, the 1944 Allied invasion of Western Europe, started in Normandy. In 1956, mainland Normandy was separated into two regions, Lower Normandy and Upper Normandy, which were reunified in 2016.

The pontifex maximus (Latin for 'supreme pontiff') was the chief high priest of the College of Pontiffs (Collegium Pontificum) in ancient Rome. This was the most important position in the ancient Roman religion, open only to patricians until 254 BC, when a plebeian first held this position. Although in fact the most powerful office in the Roman priesthood, the pontifex maximus was officially ranked fifth in the ranking of the highest Roman priests (Ordo Sacerdotum), behind the Rex Sacrorum and the flamines maiores (Flamen Dialis, Flamen Martialis, Flamen Quirinalis).

A distinctly religious office under the early Roman Republic, it gradually became politicized until, beginning with Augustus, it was subsumed into the position of emperor in the Roman imperial period. Subsequent emperors were styled pontifex maximus well into Late Antiquity, including Gratian (r. 367–383), but during Gratian's reign the phrase was replaced in imperial titulature with the Latin phrase: pontifex inclytus ("honourable pontiff"), an example followed by Gratian's junior co-emperor Theodosius the Great and which was used by emperors thereafter including the co-augusti Valentinian III (r. 425–455), Marcian (r. 450–457) and the augustus Anastasius Dicorus (r. 491–518). The first to adopt the inclytus alternative to maximus may have been the rebel augustus Magnus Maximus (r. 383–388).

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.