Irish title for the greatest prose narrative in the Fenian Cycle, usually known in English as The Pursuit of Diarmait and Gráinne. Although elements in the story date from at least as far back as the 10th century, texts survive only in Modern Irish, the oldest, from the 17th century, bearing evidence of the accretion of centuries. The love triangle of the ageing Fionn mac Cumhaill, the comely young Gráinne, and the handsome swain Diarmait Ua Duibne immediately suggests parallels with the Deirdre story from the Ulster Cycle, another story of tragic elopement. However similar the two stories are now, medieval references suggest that the original story of Diarmait and Gráinne took different directions, i.e. that Gráinne was first married to and later divorced from Fionn, and that Fionn also wooed Ailbe, another daughter of Cormac mac Airt.
Grieving for his wife Maigneis, Fionn mac Cumhaill complains to his retainers at the Hill of Allen that a man without a wife cannot sleep well. Promising him that he can have any woman he wants, Diorruing says that the most worthy in all Ireland is Gráinne, daughter of Cormac mac Airt at Tara. Fionn immediately sends emissaries, who are told that Gráinne is willing if Fionn is worthy to be Cormac's son-in-law. But at the betrothal feast it is clear that Gráinne's affections lie elsewhere. Dismayed that Fionn is older than her father, Gráinne gives admiring glances at the younger members of the Fianna, focusing on the dark curly-haired Diarmait, with whom she is soon smitten. In oral-tradition versions of the story she cannot resist his ball seirce [love spot], which he modestly keeps covered with a cap. Gráinne gives a sleeping-potion to all present except Diarmait, whom she then urges to run away with her. At first he resists out of loyalty to Fionn, but when she threatens a geis of destruction, he relents. The lovers flee across the Shannon to a forest, where Diarmait builds a house with seven doors. Fionn and his men come in immediate pursuit, but some of the Fianna try to restrain their leader's hunger for vengeance. Fionn's own son Oisín sends the hound Bran to warn the lovers, and persuades a man with a great voice to call out an alarm. Diarmait ignores both cautions and instead plants three kisses upon Gráinne in full view of the enraged Fionn. Then in a flash the lovers make a magical escape, Gráinne rescued with a cloak of invisibility in the hands of Angus Óg, Diarmait's foster-father, and Diarmait in a bold leap over the heads of Fionn and his men.
The route of the fugitive lovers takes many digressions, especially to west Munster and to Connacht. Innumerable folk variants in both Ireland and Scotland further take the lovers to all corners of the Gaelic world, as is testified by the common folk name for the Dolmen as a ‘bed of Diarmait and Gráinne’. But Diarmait is slow in his sexual approaches to Gráinne, outwardly out of respect to Fionn. In one of the most often-cited passages of the story, the two lovers are crossing a stream when a spurt of water splashes upon Gráinne's leg, prompting her taunt that it is more daring than he. Soon after their love is consummated, and in due time Gráinne becomes pregnant. This causes her craving of the red berries of the rowan tree returned from Tír Tairngire [the Land of Promise], now found in the forest of Dubros, Co. Sligo, guarded by a one-eyed, surly ogre named Searbhán. Because Searbhán is so skilled in magical arts, Diarmait cannot overcome him by conventional means until he turns Searbhán's own weapon, an iron club, against him. Both Diarmait and Gráinne then feast on the berries, finding those on the highest branches to be the most delicious. While they are aloft, Fionn and the Fianna come to rest under the rowan tree, relaxing with the board-game fidchell. When Diarmait's ally Oisín appears to be getting the worst of the match, the skilful lover aids him by adroitly dropping a rowanberry on the board to indicate the next best move, and so determines the outcome of three successive matches. Fionn angrily demands that Diarmait show himself, which he does, giving Gráinne three more kisses, before Angus Óg spirits her off to his residence at Brug na Bóinne and Diarmait once more leaps over the heads of his pursuers and escapes.
After Diarmait has turned back further attempts to capture the lovers, Angus Óg negotiates a peace between them and Fionn. In some versions Fionn then contents himself with another daughter of Cormac. Diarmait and Gráinne settle near Céis Chorainn [Kesh-corran], Co. Sligo, where they raise four or five children and live peacefully. But one night while trying to sleep Diarmait is troubled by the cry of a hound on the scent, and so leaves his bed to follow it, despite Gráinne's warning of danger. Fionn has organized a boar hunt near Ben Bulben, which all the Fianna have joined. In some versions Fionn reminds Diarmait of his geis never to hunt pig because his half-brother had been magically restored under this form, yet Fionn clearly has reasons for wanting Diarmait to join the hunt, as he also knows that the lover will be killed by a boar. Foreseeing his doom, Diarmait none the less joins the chase with his old comrades, but finds his weapons useless. When the boar charges, he is mortally wounded. Seeing him dying amidst gore and blood, Fionn stands over him gloating that all the women of Ireland should see him now that his beauty has turned to ugliness. Diarmait reminds his older captain that he has the power to heal him by carrying healing water in his magical hands. Fionn's grandson Oscar also pleads for help, which the older man then reluctantly provides; but on each of three attempts he lets the water drip through his hands, and thus Diarmait perishes.
Texts vary widely as to the outcome of the story. Sometimes Gráinne exhorts her sons to vengeance against Fionn; in other versions she mourns Diarmait until her own death; in still others she is reconciled to Fionn. Versions from oral tradition portray Gráinne unfavourably as a lewd woman, contrasting with Diarmait's chastity. In the Fenian ballads surviving in the 17th-century collection Duanaire Finn, Gráinne swallows her disgust for Fionn's age and his treatment of Diarmait, and marries him.
The love triangle between the older and younger man and the beautiful maiden has many correlatives in both Celtic and European literatures. The closest parallel in Irish tradition is, of course, the Deirdre story from the Ulster Cycle; in the popular imagination Tóraigheacht Dhiarmada agus Ghráinne has seemed less attractive because of Gráinne's hinted immorality and, in oral tradition, her marriage to Fionn after Diarmait's death. James Carney has argued that both stories derive from the late Roman love triangle of the ageing consort Mars (Fionn), Venus (Gráinne), and her lover Adonis (Diarmait). The idea that the Fionn-Diarmait-Gráinne triangle contributed to the Arthurian romance of Mark-Tristan-Iseult was suggested in the 19th century and argued convincingly by Gertrude Schoepperle in 1913.
The best modern edition and translation, superseding all others, is Tóraidheacht Dhiarmada agus Gráinne, ed. Nessa Ní Sheaghdha. Irish Texts Society, 48 (Dublin, 1967). See also R. A. Breatnach, ‘The Pursuit of Diarmuid and Gráinne’, Studies [Dublin], 47 (1958), 90–7; Alan Bruford, ‘The Fenian Cycle: Pursuits’, in Gaelic Folk-Tales and Mediaeval Romances (Dublin, 1969), 106–9; James Carney, Studies in Irish Literature and History (Dublin, 1955); A. H. Krappe, ‘Diarmuid and Gráinne’, Folk-Lore, 47 (1936), 347–61; Donald E. Meek, ‘The Death of Diarmuid in Scottish and Irish Tradition’, Celtica, 21 (1990), 335–61; Gertrude Schoepperle, Tristan and Isolt: A Study of the Sources of the Romance (London, 1913). Additionally, the tragic love story of Diarmait and Gráinne has been adapted more than a dozen times in English, including J. R. Anderson, The Pursuit of Diarmuid and Graunia (London, 1950); 9th Duke of Argyll, Diarmid: An Opera (1908); Austin Clarke, The Vengeance of Fionn (Dublin, 1917); Katharine Tynan Hinkson, ‘The Pursuit of Diarmuid and Grainne’, in Shamrocks (London, 1887), 1–54; E. R. Watters, The Weekend of Dermot and Grace (Dublin, 1963); William Butler Yeats and George Moore, Diarmuid and Grania (1901), with incidental music by Sir Edward Elgar.