Roman Catholic Diocese of Tréguier

The former Breton and French diocese of Tréguier existed in Lower Brittany from about the sixth century, or later, to the French Revolution. Its see was at Tréguier, in the modern department of Côtes-d'Armor.

The title continues in the contemporary diocese of Saint-Brieuc and Tréguier.

History
St. Tudgual (Tugdual, Tudual), said to be the nephew of St. Brieuc (who had emigrated from Cardigan), was a bishop who came to Brittany from overseas (Scotland ), and was appointed by his uncle Brieuc at the close of the fifth century as superior of the monastery of Tréguier, which Tudual had founded. The biography of St. Tudual, composed after the middle of the ninth century, relates that Tudual, wishing to confirm his authority by royal approval, travelled to the court of King Childebert I, who ordered him consecrated Bishop of Tréguier. Louis Duchesne, however, argued that it was King Nomenoe who, in the middle of the ninth century, had the monastery of Tréguier raised to the dignity of an episcopal see.

Numerous synods were held at Tréguier in the fourteenth and fifteenth centuries, and passed regulations for the discipline of the Breton churches.

to 1400

 * c. 1032: Wiliam I.
 * c. 1045: Martin
 * c. 1086: Hugo I. de Saint-Pabutral
 * c. 1110–c. 1128: Raoul I.
 * c. 1150–c. 1175: William II.
 * 1175–1179: Ives I Hougnon
 * 1179–c. 1220: Geoffroi I. Loiz
 * c. 1224–c. 1237: Stephan
 * c. 1238: Peter I.
 * 1255–c. 1265: Hamon
 * c. 1266–c. 1271: Alain I. de Lezardrieu
 * c. 1284: Alain II. de Bruc
 * 1286–c. 1310: Geoffroi II. de Tournemine
 * c. 1317: Jean I. Rigaud
 * c. 1324: Pierre II. de l'Isle
 * 1327–1330: Ives II. Le Prévôt de Bois Boëssel
 * 1330–1338: Alain III. de Haïloury
 * 1339–c. 1345: Richard du Poirier
 * c. 1354: Robert I. de Peynel
 * 1355–1358: Hugues II. de Monstrelet
 * 1358–1362: Alain IV.
 * 28 November 1362 – 1371: Even Bégaignon
 * 12 June 1372 – 1378: Jean II. Brun
 * 1378–1383: Thibaud de Malestroit
 * 1383–1384: Hugues III. de Keroulay
 * 1385–3 May 1401: Pierre III. Morel

1400 to 1600

 * 1401–1403: Ives III. Hirgouët
 * 1404–1408: Bernard de Peyron
 * 1408–1416: Christophe I. d'Hauterive
 * 15. December 1417 – 1422: Matthieu du Kosker
 * 29. April 1422 – 1430: Jean III. de Bruc
 * 1430–27. August 1435: Pierre IV. Piédru (or Predou) (also Bishop of Saint-Malo)
 * 1435–1441: Raoul II. Rolland
 * 4. May 1442 – 1453: Jean IV. de Plouec
 * 16. March 1454–23. September 1464: Jean V. de Coetquis
 * 8. January 1466 – 1479: Christophe II. du Châtel
 * 1480–1483: Cardinal Raphaël de Saint-Georges
 * 1483–1502: Robert II. Guibé
 * 1502–7. March 1505: Jean VI. de Talhouët
 * 22 November 1505–16. November 1537: Antoine du Grignaux
 * 14 June 1538 – 1540 or 1541: Louis de Bourbon-Vendôme
 * 1541–1544: Cardinal Hippolyte d'Este
 * 1544–1545: Jean VII. de Rieux
 * 8 June 1545 – 1547: François I. de Manaz
 * 1548–27. October 1566: Jean VIII. Juvénal des Ursins
 * 1566–1572: Claude de Kernovenoy
 * 1572–1583: Jean-Baptiste Le Gras
 * 1583–1593: François II. de La Tour
 * 1593–29. October 1602: Guillace III. du Halgoët

1600 to 1800

 * 1604–29. July 1616: Georges-Louet-Adrien d'Amboise
 * 1616–1620: Pierre V. Cornullier
 * 1620–14. September 1635: Gui Champion
 * 1636–19. August 1645: Noël des Landes'
 * 1646–1679: Balthasar Grangier de Liverdis
 * 1679–1686: François-Ignace de Baglion
 * 1686–15. May 1694: Eustache Le Sénéchal de Carcado (or Kercado)
 * 1694–1731: Olivier Jégou de Kervilio
 * 1731–1745: François-Hyacinthe de La Fruglaye de Kervers
 * 1746–30. August 1761: Charles-Gui Le Borgne de Kermorvan
 * 1761–1766: Joseph-Dominique de Chaylus
 * 26. April 1767 – 1773: Jean-Marc de Royère
 * 1773–1775: Jean-Augustin de Frétat de Sarra
 * 6 August 1775 – 1780: Jean-Baptiste-Joseph de Lubersac
 * 1780–1790 (1801): Augustin-René-Louis Le Mintier

Reference works

 * pp. 641–642. (Use with caution; obsolete)
 * (in Latin) p. 494.
 * (in Latin) p. 254.
 * p. 317.
 * pp. 342.
 * p. 387.
 * pp. 413–414.

Studies

 * second edition
 * second edition