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Mac Fhirbhisigh, Dubhaltach Óg [Duald MacFirbis, Dudly Ferbisie, Dualdus Firbissius]locked

(c. 1600–1671)
  • Nollaig Ó Muraíle

Mac Fhirbhisigh, Dubhaltach Óg [Duald MacFirbis, Dudly Ferbisie, Dualdus Firbissius] (c. 1600–1671), scribe and genealogist, was born about 1600 (not, as often suggested, in 1585), probably at Lackan (Irish Leacán Meic Fhir Bhisigh), co. Sligo. He was the eldest of four sons of Giolla Íosa Mór (d. c.1643), son of Dubhaltach Mór, who was himself an accomplished scribe, and belonged to a leading hereditary learned family of north Connaught who served as historians and poets to the Ó Dubhda (O'Dowd) chieftains of Tireragh in west co. Sligo; his mother was from the Mac Diarmada family. Contrary to what is commonly stated, he was not a direct descendant of Gilla Ísa Mac Fir Bisig (fl. 1392–1418), who compiled and partly wrote the important Irish manuscript called the Book of Lecan and a significant portion of the Yellow Book of Lecan. Virtually nothing is known of his early life, but he may well have received some of his education in Galway city, where he would have been a near-contemporary of John Lynch and Patrick Darcy. He may also have received more traditional training at a school run by the learned family of Mac Aodhagáin, celebrated lawyers and historians, at Ballymacegan on the shores of Lough Derg in north co. Tipperary. He Anglicized his name as Dudly Ferbisie and it was Latinized as Dualdus Firbissius, from which the commonly used form Duald MacFirbis derives.

In May 1643 at Ballymacegan (perhaps on a return visit), Mac Fhirbhisigh copied an ancient glossary called Dúil Laithne ('Book of Latin'). In that same year he transcribed from an old MacEgan manuscript a collection of early annalistic material from south Leinster now known as the ‘fragmentary annals’ of Ireland. The copy was made for ‘Rev Dr John Lynch’, then archdeacon of Tuam. It was probably about this time too, perhaps while still at Ballymacegan, that he transcribed a valuable early Irish legal tract, Bretha neimheadh déidheanach, and an important collection of early Irish annals, Chronicum Scotorum.

Mac Fhirbhisigh was settled in Galway by the spring of 1645, when he transcribed an ancient historico-genealogical text, Senchas síl Ír. His source was the late fourteenth-century manuscript called the Book of Uí Mhaine (but known to him as the Book of Ó Dubhagáin). The copy of the Senchas, now incorporated in his 'Book of genealogies', is of particular value since almost a third of the Síol Ír text has since been lost from the exemplar.

Towards the end of 1647 Mac Fhirbhisigh completed a translation from English into Irish (begun by others over a decade earlier) of two books containing the rule of St Clare and other documents pertaining to the order of Poor Clares, which had a house in Galway. He gives his place of writing as 'The college of Galway', that is, the collegiate church of St Nicholas or one of the attached buildings, where he continued to work over the next few years. By the spring of 1649 he was hard at work on his magnum opus, the monumental 'Leabhar genealach' ('Book of genealogies'), an enormous compendium of Irish genealogical lore covering the period from pre-Christian times to the mid-seventeenth century and collected from a variety of sources, some of them now lost. In August of that year he used the celebrated annals of the four masters as a source for a catalogue of the kings of Ireland, extending from prehistoric times down to the twelfth century. By the close of 1650 he had completed the main text of the 'Book of genealogies', including a detailed general index, having laboured during a particularly disturbed period of Galway's history. Already buffeted by the growing storm of war, the city was devastated in 1649–50 by the bubonic plague, which reportedly killed some 3700 of the inhabitants. In the middle of 1651 Galway came under siege from Sir Charles Coote's parliamentarian forces and underwent great privations before its capitulation nine months later. It is not known whether Mac Fhirbhisigh remained in the city during this period or whether he made his escape before the enemy closed in.

In summer 1653 at an undisclosed location (but possibly elsewhere in co. Galway) Mac Fhirbhisigh added hagiographical material to the 'Book of genealogies', some of it taken from the early fifteenth-century Leabhar Breac. By April 1656 he was back in his home area of west Sligo or north-east Mayo as a witness to the marriage of his hereditary lord, Dathí Óg Ó Dubhda (David O'Dowda), to the latter's cousin, Dorothy O'Dowd; in fact, he may have drafted the interesting 'Marriage articles' (in English). In 1656, also, he compiled a work on early Irish authors, which is now lost except for a partial copy which he commenced in May 1657. In October 1657, in Sligo town, he copied into the 'Book of genealogies' some particularly interesting early material from sources which are no longer extant. In the early 1660s he was listed as liable to pay hearth-tax on a dwelling in Castletown, some miles north of his native Lackan. About this period he is mentioned in print for the first and only time in his lifetime, in his friend John Lynch's Cambrensis eversus, which was published in France in 1662.

In 1664 Mac Fhirbhisigh made significant additions to the 'Book of genealogies' but gives no indication of where he found or transcribed this new material. It may have been in Dublin, which he had certainly reached by the end of the following year when he penned a bilingual genealogy of the Berminghams, barons of Athenry. About this time he found employment with the Anglo-Irish historian and antiquary Sir James Ware. During 1665 and 1666 he furnished Ware with English translations of portions of the annals of Inisfallen and of Tigernach relating to the twelfth and thirteenth centuries and of the annals of Lecan (now lost) covering the years 1443 to 1468. He also wrote a tract in English on early Irish bishops, drawing on various documents (few of them now extant) from the archives of Clann Fhirbhisigh. During a sojourn back in Tireragh in spring 1666 he compiled a work in Irish on early Irish bishops and then set to work on an abridged version of the 'Book of genealogies'. Since his original copy of the abridgement does not survive it is not known if he ever finished it; both of the two earliest extant copies (one certainly and one possibly from the early eighteenth century) appear incomplete. He was back in Dublin for some weeks at the time of Ware's death on 1 December but then returned to Connaught for the last time. Seeking patronage from Sir Dermot O'Shaughnessy in south Galway, he composed a poem in his honour, but we do not know if it produced the desired effect. He may next have sought support from the marquess of Antrim, in Larne, co. Antrim, where he left several important manuscripts in the hands of the local learned family of Ó Gnímh. He then returned to Tireragh and in January 1671 at Doonflin, about a dozen miles east of Lackan, he was stabbed to death by one Thomas Crofton in circumstances which are unclear. He was buried in Kilglass old cemetery, co. Sligo.

Mac Fhirbhisigh's scholarly achievement was substantial. As one of the last traditionally trained members of a hereditary learned family, his labours ensured the survival of several important sources of medieval and early modern Irish history. Without his diligence as copyist, compiler, and translator, knowledge of various aspects of early and medieval Ireland would be much the poorer. It is ironic that someone who supplied so much information about others left few details about his own life; nothing is known of his personal appearance, his marital status, or extensive portions of his life.


  • N. Ó Muraíle, ‘Aspects of the intellectual life of seventeenth century Galway’, Galway history and society: interdisciplinary essays on the history of an Irish county, ed. G. Moran and R. Gillespie (1996), 149–211, esp. nn. 140–97
  • W. O'Sullivan, ‘The manuscript collection of Dubhaltach Mac Fhirbhisigh’, Seanchas: studies in early and medieval Irish archaeology, history and literature in honour of Francis J. Byrne, ed. A. P. Smyth (2000), 439–47


  • BL, MSS
  • BL, translations and extracts, Add. MS 4799
  • Bodl. Oxf., MSS
  • Royal Irish Acad., MSS
  • TCD, MSS
  • University College, Dublin, MSS, book of genealogies
, 63 vols. (1885–1900), suppl., 3 vols. (1901); repr. in 22 vols. (1908–9); 10 further suppls. (1912–96); (1993)