Eusebia (Greek: Εύσεβία, died 360) was the second wife of Roman emperor Constantius II. The main sources for the knowledge about her life are Julian's panegyric "Speech of Thanks to the Empress Eusebia", as well as several remarks by the historian Ammianus Marcellinus.
Family
Julian's "Panegyric In Honour Of Eusebia", the primary source for her family and ancestry, states that "she is of a family line that is pure Greek, from the purest of Greeks, and her city is the metropolis of Macedonia". Her father was reportedly the first member of the family to serve as a consul. The Panegyric never gives his name, but modern historians identify him with Flavius Eusebius, consul in 347. This Eusebius is identified elsewhere as a former Magister Equitum and Magister Peditum, which means he had served as a military commander of both the cavalry and infantry of the Roman army. The Prosopography of the Later Roman Empire considers it probable that his consulship came at the end of his military career. He is later styled "Comes".
The Panegyric mentions that Eusebia's father died some time before she married Constantius. Her mother, also unnamed in the speech, did not remarry, but "devoted herself to her children, and won a great reputation for prudence, so great indeed that whereas Penelope, while her husband was still on his travels and wanderings, was beset by those young suitors… no man however fair and tall or powerful and wealthy ever ventured to approach [Eusebia's mother] with any such proposals. And her daughter the Emperor deemed worthy to live by his side".
Ammianus Marcellinus says that Eusebia had two brothers, Eusebius and Hypatius, both of whom served as consuls. According to Ammianus, a corrupt official named Palladius accused these men of treason during the reign of Valens. Although Palladius failed to prove his case, "the accused were punished with exile and with fines; but shortly afterwards they were recalled, had their fines remitted, and were restored to their former rank and honour unimpaired."
The brothers have been identified with Flavius Eusebius and Flavius Hypatius, co-consuls in 359. Eusebius is described as a rhetor in an epistle by Libanius. In the Panegyric, Julian alludes to both brothers having secured high offices through the influence of Eusebia. Libanius identifies Eusebius as governor of the Hellespont c. 355. He was next sent to Antioch and then appointed governor of Bithynia. He held no known offices following his term as consul. Hypatius was possibly vicarius of the city of Rome in 363. Libanius mentions Hypatius appointed Praefectus urbi, c. 378–379. Gregory of Nazianzus mentions Hypatius visiting Constantinople in 381. He served as Praetorian prefect of both the Praetorian prefecture of Italy and the Praetorian prefecture of Illyricum, c. 382–383. An inscription of Gortyn, Crete praises him as the most illustrious of the consuls and praetorian prefects.
Empress
The Panegyric of Julian places her marriage to Constantius prior to the defeat of rival emperor Magnentius, who was dead by August 353. The marriage of Constantius and Eusebia may have occurred earlier in that year. "When [Constantius] acquired the throne that had belonged to his ancestors, and had won it back from him [Magnentius] who had usurped it by violence and desired to wed that he might beget sons to inherit his honour and power, deemed [Eusebia] worthy of his alliance, when he had already become of almost the whole world". In the original Medieval Greek text the word is "ecumene", a term originally used in the Greco-Roman world to refer to the inhabited Earth. Over time, the word came to mean the civilized world, and to be synonymous with the Roman Empire. The Prosopography interprets the text to mean that Constantius had yet to defeat Magnentius at the time.
Eusebia won much praise for her wisdom and kindness, as well as her loyalty to Constantius, who honoured her by renaming the Dioecesis Pontica as Pietas, the Latin equivalent of the Greek name Eusebia. Both names refer to piety as well as family loyalty, including the loyalty of a wife to her husband. The Epitome de Caesaribus, attributed to Aurelius Victor, describes the imperial couple in less favorable terms: Constantius "was addicted to the love of eunuchs, courtiers, and wives, by whom – satisfied by no deviant or unlawful pleasure – he used to be polluted." Eusebia, his favourite among this alleged multitude of lovers, "was indeed elegant, but, through Adamantiae and Gorgoniae and other dangerous abettors, harmful of her husband's reputation, contrary to what is customary for more upright females whose precepts often aid their husbands."