Fiachnae Lurgan (‘of Lurga’ [placename?]) (d. 626), son of Báetán and overking of Ulaid, belonged to the lineage of Uí Choíldub within the dynasty of Dál nAraide. Fiachnae, whose grandfather Eochaid is numbered among the overkings of Ulaid, had a brother, Fiachra Cáech (d. 608), and a sister, Cumne Fhinn. The ‘Banshenchas’ (lore of women) maintains that Fiachnae was married to Caintigern (daughter of a Scottish king, Conndach), mother of his son Mongán; she was healed of an illness by Comgall (qv) of Bangor, according to the latter's Latin Life (§52). Fiachnae had at least two other sons, Eochaid Iarlaithe and Scandal Sciathlethan.
Fiachnae may have fought against the Osraige at Tolae in the midlands as early as 573 (as a glossator in the Annals of Ulster believed); in any event, he had come to prominence by 588 when he slew the reigning Dál nAraide overking of Ulaid, Áed Dub (qv). His advent to power, perhaps with the support of the Dál Riata king Áedán (qv) son of Gabrán, was in any case facilitated by a scarcity of candidates among the rival dynasty of Dál Fiatach. Be that as it may, Fiachnae sought to maintain Ulster supremacy in the midlands; in 594 he defeated the Cianachta of Brega at Eudann Mór. Three years later he was victorious over the Munstermen – which is significant, whether or not the battle-site of Sliab Cua is located in the Knockmealdown mountains. He also faced opposition within the north: in 601 he defeated his Dál Fiatach rival, Fiachnae son of Demmán – a nephew of Báetán (qv) son of Cairell – at Cúl Caíl (perhaps Kilkeel, Co. Down). It is possible that his sister's marriage to his Dál Fiatach namesake was part of an agreement following this battle. In any event, peace between the two dynasties followed for some twenty years.
It appears that Fiachnae also ensured a marriage-alliance with Dál Riata: his son Scandal was married to a sister of Connad Cerr, head of the latter dynasty. Certainly, Fiachnae claimed authority over Dál Riata and that dynasty's conquests in Scotland. There are strong indications that he campaigned there; the story ‘Compert Mongáin’ claims that Fiachnae went to the aid of Áedán son of Gabrán. A lost saga told of his expedition to Dún Guaire i Saxanaib (Bamborough), which may be reflected in an otherwise puzzling annal entry recording expugnatio Ratho Guali (AU 623). Significantly, according to the Annals of the Four Masters, his son Mongán was slain by the Britons of Strathclyde in 625. Perhaps his international stature lies behind the apparent reference to Fiachnae in ‘Baile Chuinn’, the Old Irish list of the kings of Tara. Stories of Fiachnae's generosity and righteousness abound; he is said to have been hospitable to the poets when they were threatened with banishment by the king of Tara, Áed (qv) son of Ainmire (qv). He also had a reputation as a collector of relics.
Fiachnae was slain by his Dál Fiatach rival Fiachnae son of Demmán in the battle of Drong (perhaps near Knocklayd, Co. Antrim) in 626. His death was avenged the following year when his killer fell at Ard Corann, at the hands of his son's brother-in-law Connad Cerr and his grandson Congal Clóen (qv). The latter was Fiachnae's immediate successor in the kingship of Dál nAraide; he also aspired to overkingship of Ulaid. Fiachnae's son Eochaid Iarlaithe (d. 666) subsequently reigned as king of Dál nAraide.