Britonia was the name of a bishopric in the former Roman province of Gallaecia in north-west Iberia, and is used by modern historians in reference to an early medieval settlement of Britons in the same area. The settlement, often described as a southern counterpart to Brittany, formed part of the wider British diaspora of the fifth and sixth centuries. There is contemporary evidence of the settlement itself being called Britonia: in the medieval sources that survive, the name denotes the diocese and on occasion a place. The see is recorded in the , a list of the bishoprics of the Kingdom of the Suebi compiled in the second half of the sixth century, as the 'see of the Britons', to which belonged the churches of the Britons, the monastery of Maximus and churches in Asturias.
Five of the see's clergy can be identified with confidence from the acts of church councils held between 572 and 675: its bishops, Mailoc, Metopius, Sonna and Bela, and the priest Mactericus, who represented Sonna at the Eighth Council of Toledo in 653. Mailoc, who subscribed the acts of the Second Council of Braga in 572, bore a Brittonic name, but the linguistic affiliation of most of his successors' names remain disputed. The change in the see's designation, from a bishop 'of the Britons' to a bishop of the 'church of Britonia', has been read as evidence that an ethnic bishopric serving the Britons became a conventional territorial diocese at some point between 572 and 633. Historians have also disagreed over whether the church preserved customs of the so-called 'Celtic' church, particularly the form of tonsure worn by lectors in Gallaecia and condemned by the Fourth Council of Toledo in 633.
No representative of the see is recorded after 675. The traditional view that it was destroyed during the Muslim conquest of the early eighth century, but it has also been argued that the diocese either disappeared or changed its name in the late seventh century. Its territory is generally thought to have lain at least partly within the later diocese of Mondoñedo, while its Asturian churches passed to Oviedo. The name appears in later forgeries produced at Oviedo, in which Britonia served as a cipher for Mondoñedo, while 'Britonia' survives in the name of the parish of Santa María de Bretoña in the province of Lugo, traditionally regarded as the centre of the see. Britonia is now a titular see of the Catholic Church.
Sources The documentary evidence for Britonia is slight, comprising the entry for the see in the Parochiale Suevorum; the subscriptions of its bishops, or of their representative, to the acts of councils held at Braga and Toledo between 572 and 675; and a body of later charters, conciliar acts and lists of sees, many of them forged or interpolated, in which the see's name recurs between the ninth and twelfth centuries. To these may be added the results of excavations at Bretoña in 1970 and 1971.
Name The name Britonia is a modern scholarly label: there is no proof that contemporaries ever used it for the settlement, and in the medieval documents that survive it refers to the short-lived diocese, which historians often call the , or occasionally to places. In the sixth century the see was defined by the people it served. The Parochiale assigns churches 'to the see of the Britons' (for which some manuscripts read Britoniorum, Britanorum, sedem Bretonicam or sedem Bretunicam),, cited in . and the manuscripts of the Second Council of Braga describe Mailoc either as bishop of the or, in readings such as britunorum and brittanorum, as bishop 'of the Britons'., cited in ; , cited in . Simon Young preferred the latter reading, which is supported by the Parochiale and echoes the title of an earlier 'bishop of the Britons' in Gaul, and explained 'bishop of Britonia' as an extrapolation from the usage of later councils. In the seventh century the see's bishops subscribed as bishops of the , or ., cited in . read the change as marking the passage from a personal church, defined by ethnicity, to a territorial church with a fixed seat. According to Young, the earlier, ethnic designation is also "our firmest proof that the diocese of Britonia and the settlement Britonia are, indeed, related": without it, it could be argued that the see took its name from one of the many place-names in the north-west containing the element Brit- or Bret-, and had no connection with the British migration. As a noun, Britonia or Britona is attested only from the ninth century.
Origins
Britonia was part of the wider British diaspora of the fifth and sixth centuries, and is often understood as a southern counterpart to Brittany. The origins of the settlers are obscure. No place-names, inscriptions or record of their language survive to indicate their provenance, although it is clear that they were orthodox members of the Church, or became so soon after their arrival. Louis Duchesne placed their arrival at the end of the fifth century or the beginning of the sixth, a chronology that García y García accepted., cited in . He argued that the church of the Britons established and organised itself in the century between the end of Hydatius' chronicle in 469 and the conversion of the Suebi to Catholicism around 559, a period in which almost nothing is known of the Galician church. He also thought it possible that Britons had reached Gallaecia earlier, whether to take charge of the property of the Galician followers of Priscillian confiscated by Magnus Maximus in the 380s or, as he suspected without direct evidence, in support of the Catholic population against the Suebi in the 430s.
Whether the migrants came from Britain itself or from Brittany is uncertain. Pierre David argued firmly for Brittany, while E. A. Thompson held that the question could not be settled on the available evidence, and García y García agreed that no document favours either possibility.; ; both cited in . Nora K. Chadwick, who associated the Galician settlement with the migration to Brittany, left open whether its church had been founded from Ireland, from Britain or from Brittany. She did, however, establish from Kenneth Jackson that Mailoc's name represents the Celtic Maglacos, and traced the form Maeloc to a document from Bodmin in Cornwall, which regarded as at least an indication that the Britons may have come from the West Country..Chadwick's views are discussed, with reference to and , in .
Livermore questioned whether the Britons of Gallaecia need be connected with the settlement of Brittany at all. He observed that none of the see's later bishops bore a Celtic name, as Chadwick had noted, and that neither place-names nor any other evidence preserves a trace of the Celtic saints who attest the continuing association between Britain and Brittany; the incorporation of the monastery of Maximus seemed to him more likely to mark the end of a Celtic tradition than a renewal of the kind that took place in Brittany. Now doubting his earlier view that the Britons were unlikely to have reached Gallaecia before Armorica, or within the period covered by Orosius and Hydatius, he noted that the Britons were probably poor peasants or soldiers, which might explain their absence from the chronicle of Hydatius, who was chiefly concerned with the security of the cities and the landowners. He looked in particular to British troops in Roman service in the early fifth century. The army that the usurper Constantine III sent into Spain under his son Constans included, he believed, a British contingent, and a letter of the emperor Honorius, preserved at the monastery of Roda and perhaps issued at Rome in 416, rewarded Britons among the troops serving in Spain. This, Livermore noted, is the first occasion on which a force of Britons is found to have been rewarded so far south, but he left open whether they were the ancestors of the Britons of Gallaecia.; ; both cited in .
Location Except for that of the monastic see of Dumio, the entry for the see of the Britons is the only one in the Parochiale that names no individual churches. It assigns to the see 'the churches that are among the Britons, together with the monastery of Maximus, and those that are in Asturias'; four manuscripts omit the reference to Asturias., cited in ; , cited in . On this basis García y García placed the settlement in the northern part of the modern province of Lugo and in western Asturias. Livermore located the Britons between Ferrol and the river Eo, and noted that some versions of the Parochiale add 'as far as the river Ova'. The see lay within the ecclesiastical province of Lugo, and probably bordered the dioceses of Lugo and Astorga. Young cautioned that its exact location is unknown, but noted a consensus, going back to Enrique Flórez, that at least part of it coincided with the later diocese of Mondoñedo, now Mondoñedo-Ferrol.; ; both cited in .
Bretoña The traditional centre of the see is the parish of , in the municipality of A Pastoriza in the north of the province of Lugo. García y García considered it beyond doubt that the see, once it had become a territorial diocese, was seated at Britonia or Britona, the modern Bretoña, and Livermore located the see's central monastery, the monastery of Maximus, there. Excavations carried out by in 1970 and 1971 found, on the site of a double-ditched hillfort (), the apse of a church surrounded by burials of the Visigothic period, together with the remains of adjoining buildings that may have housed a monastic community., cited in . Chamoso attributed these remains to the British occupation and the creation of the see, which he regarded as an important residential see that survived until the eighth century and was then replaced by San Martiño de Mondoñedo, in his view the former monastery of Maximus., cited in . García y García accepted the importance of the finds, and did not think the identification of the monastery of Maximus with San Martiño unfounded in principle, but he knew of no source that supported it, and rejected Gildas Bernier's argument for it from the architecture of the church there., cited in .
The present parish church of Bretoña dates from the eighteenth century. Its east wall bears a damaged inscription recording the dedication of a church to Santa María, which Bernier dated to the ninth century and García y García to the eleventh or twelfth; its last line, which is difficult to read, may indicate that the church adjoined a monastic community ()., cited in . Bretoña had belonged to the diocese of Mondoñedo since the early Middle Ages, and the record of one of two canonical visitations of the parish made from Mondoñedo in the fourteenth and fifteenth centuries shows that its priest owned, besides the usual liturgical books, a manuscript of the customs of the 'black monks'. García y García noted that by that date the phrase denoted monks of Benedictine descent, and that any connection with the church's original monastic character is unknown., cited in .
The sixth-century see The Parochiale Suevorum