Fergnae mac Óengusso Ibdaig (died 557) was a Dal Fiatach king of Ulaid. He was the nephew of Muiredach Muinderg mac Forgo (died 489) and grandson of Forga mac Dallán, previous kings.Byrne, Table 6; Charles-Edwards, appendix XXI; Mac Niocaill, pg.74
He ruled the Dal Fiatach from 532 and succeeded Eochaid mac Condlai of the Dal nAraide as king of Ulaid in 552. He ruled from 552 to 556.the Book of Leinster gives him a reign of 5 years and Laud Synchronisms 3 years
He was slain at the Battle of Druim Cleithe (Kilclief, County Down) by his cousin Demmán mac Cairill (died 572) who had support of the Uí Echach nÁrda, another branch of the Dal Fiatach.Annals of Ulster AU 557.1; Annals of Tigernach AT 556.2 As a result of this battle, his branch of the Dal Fiatach known as the Ui Ibdaig were excluded from the throne.Ó Cróinín pg.216-217 places it in the year 533
The naming of the Uí Ibdaig is variously interpreted. Some propose that it was named for Fergnae's father's mother,Charles-Edwards, pg.624 while others suggest that Ibdaig is an epithet—the Hebridean—applied to his father, who should be identified with the eponymous ancestor of the Cenél nÓengusa of Islay.Fraser, pp. 159–160. The toponym Ibdaig has also been identified as the pre-Norse toponym for Uist.
Notes
References
Annals of Ulster at at University College Cork Annals of Tigernach at at University College Cork Byrne, Francis John (2001), Irish Kings and High-Kings, Dublin: Four Courts Press, Charles-Edwards, T. M. (2000), Early Christian Ireland, Cambridge: Cambridge University Press,
Gearoid Mac Niocaill (1972), Ireland before the Vikings, Dublin: Gill and Macmillan Dáibhí Ó Cróinín (2005), A New History of Ireland, Volume One, Oxford: Oxford University Press
External links CELT: Corpus of Electronic Texts at University College Cork