Gaius Sollius (Modestus) Apollinaris Sidonius or Saint Sidonius Apollinaris (November 5 of an unknown year, perhaps 430 – August, 489) was a poet, diplomat, and bishop. Sidonius is “the single most important surviving author from fifth-century Gaul” according to Eric Goldberg.
He was one of four fifth-to sixth-century Gallo-Roman aristocrats whose letters survive in quantity; the others are Ruricius bishop of Limoges (died 507), Alcimus Ecdicius Avitus, bishop of Vienne (died 518) and Magnus Felix Ennodius of Arles, bishop of Ticinum (died 534). All of them were linked in the tightly bound aristocratic Gallo-Roman network that provided the bishops of Catholic Gaul. His feast day is August 21.
St. Sidonius Apollinaris
Sidonius was born in Lugdunum (Lyons). His father Apollinaris (born circa 405) was the Prefect of Gaul under Valentinian III; he recalls with pride being present with his father at the installation of Astyrius as consul for the year 449. Sidonius’ grandfather was Praetorian Prefect of Gaul prior 409 and a friend of his successor Decimus Rusticus. Sidonius may be a descendant of another Apollinaris who was Prefect of Gaul under Constantine II between 337 and 340.
Sidonius married Papianilla, the daughter of Emperor Avitus, around 452. This union produced one son, Apollinaris, and at least two daughters: Sidonius mentions in his letters Severina and Roscia, but a third, Alcima, is only mentioned much later by Gregory of Tours, whom Theodor Mommsen has speculated may be identified with one of his other daughters. His known acquaintances include bishop Faustus of Riez and his theological adversary Claudianus Mamertus; his life and friendships put him in the center of 5th century Roman affairs.
In 457 Majorian deprived Avitus of the empire and seized the city of Lyons; Sidonius fell into his hands. However, the reputation of the aristocrat’s learning led Majorian to treat him with the greatest respect. In return Sidonius composed a panegyric in his honour (as he had previously done for Avitus), which won for him a statue at Rome and the title of count. In 467 or 468 the emperor Anthemius rewarded him for the panegyric which he had written in honour of him by raising him to the post of Urban Prefect of Rome until 469, and afterwards to the dignity of Patrician and Senator. In 470 or 472, he was elected to succeed Eparchius in the bishopric of Auvergne (Clermont, now Clermont-Ferrand).
On the capture of that city by the Goths in 474 he was imprisoned, as he had taken an active part in its defense; but he was afterwards released from captivity by Euric, king of the Goths, and continued to shepherd his flock as he had done before; he did so until his death.
Sidonius’s relations have been traced over several generations as a narrative of a family’s fortunes, from the prominence of his paternal grandfather’s time into subsequent decline in the 6th century under the Franks. Sidonius’s son Apollinaris, who was a correspondent of Ruricius of Limoges, commanded a unit raised in Auvergne on the losing side of the decisive Battle of Vouille, and also served as bishop of Clermont for four months until his death. Sidonius’s grandson Arcadius, on hearing a rumor that the Frankish king Theuderic I had died, betrayed Clermont to Childebert I, only to abandon his wife and mother when Theuderic appeared; his other appearance in the history of Gregory of Tours is as a servant of king Childebert.
His extant works are his Panegyrics on different emperors (in which he draws largely upon Statius, Ausonius and Claudian), which document several important political events. Carmen 7 is a panegyric to his father-in-law Avitus on his inauguration as emperor. Carmen 5 is a panegyric to Majorian, which offers evidence that Sidonius was able to overcome the natural suspicion and hostility towards the man who was responsible for the death of his father-in-law. Carmen 2 is a panegyric to the emperor Anthemius, part of Sidonius’ efforts to be appointed Urban Prefect of Rome; several samples of occasional verse; and nine books of Letters, about which W.B. Anderson notes, “Whatever one may think about their style and diction, the letters of Sidonius are an invaluable source of information on many aspects of the life of his time.” While very stilted in diction, these Letters reveal Apollinaris as a man of genial temper, fond of good living and of pleasure. A letter of Sidonius’s addressed to Riothamus, “King of the Brittones” (c. 460) is of particular interest, since it provides evidence that a king or military leader with ties to Britain lived around the time frame of King Arthur. The best edition is that in the Monumenta Germaniae Historica (Berlin, 1887), which gives a survey of the manuscripts. An English translation of his poetry and letters by W.B. Anderson, with accompanying Latin text, have been published by the Loeb Classical Library (volume 1, containing his poems and books 1-3 of his letters, 1939; remainder of letters, 1965).
Gregory of Tours speaks of Sidonius as a man who could celebrate Mass from memory (without a sacramentary) and give unprepared speeches without any hesitation.
Apollinaris alludes to the date of his birthday in a short poem addressed to his brother-in-law Ecdicius, Carmen 20.
 The Fall of the Roman Empire Revisited: Sidonius Apollinaris and His Crisis of Identity
 Ralph W. Mathisen, “Epistolography, Literary Circles and Family Ties in Late Roman Gaul” Transactions of the American Philological Association 111 (1981), pp. 95-109.
 Epistulae, VIII.6.5; translated by W.B. Anderson, Sidonius: Poems and Letters (Harvard: Loeb Classical Library, 1965), vol. 2 p. 423
 Gregory of Tours, History of the Franks, 2.21. This is confirmed by the otherwise oblique allusion in Sidonius’ own Epistuale 2.2.3.
Severina, Epistulae II.12.2; Roscia, Epistulae V.16.5; Alcima, Gregory of Tours Decem Libri Historiarum, III.2
 Gregory of Tours, 2.37, 3.2
 Gregory of Tours, 3.9, 11
 In his introduction to Sidonius: Poems and Letters (Cambridge: Loeb, 1939), vol. 1, p. lxiv.
 Gregory of Tours, 2.22
(cfr. Encyclopædia Britannica)