This tale is redolent of the sad story of Deirdre and Naoise and is probably the most travelled of the Irish romances. It became well-known in Europe and is thought to have been the source of the story of Tristan and Isolt. An older man’s love for a younger woman, elopement, love versus honour, a chase all over Ireland, great leaps, rescue by the gods, death by a boar and loss of honour by a great man are all there.
In this story we find Fionn, as an older man, looking for a new wife. His men suggest one of the daughters of the king. The necessary diplomatic moves are made and Fionn arrives in Tara to meet Gráinne, his prospective bride. At the preparatory feast Gráinne sets eyes on Diarmaid and is entranced by him (remember his love spot). She forces him to elope with her and they are chased all over Ireland by an avenging Fionn. Many of the Fianna are sympathetic to Diarmaid knowing that he was honour bound (against his will) to be disloyal to his leader, because of the obligation or geis that Gráinne had placed on him.
They were cornered in a wood near the Shannon but Aonghus, Diarmaid’s godfather and of the Otherworld, intervened and spirited Gráinne away. Fionn made a gigantic leap over the surrounding Fianna and escaped. The chase continued…
The couple went into the south-west and gained a massive warrior servant on the way who carried Gráinne. They slept in a cave looking over Glenbeigh. Fionn had sent three sea pirates from the Ictian Sea (North Sea) in ships and accompanied by many men and three poisonous hounds. Diarmaid defeated the sea pirates and slaughtered their hounds when they continued to pursue him. The chase continued…
They went north and, while they had to this point not been lovers, they finally succumbed. They reached a forest where an ogre lived who protected a rowan tree from which no fruit was to be taken. Gráinne wanted to taste the berries and finally Diarmaid had to kill the ogre to satisfy her. Fionn had learnt where they were and surrounded them in the tree. Once again Aoghus rescued them but this time he went to the high-king, Cormac, and reached agreement that they should be left alone.
They settled in west Kerry and had several children. They also had homes in Leinster and Connacht. While staying in Connacht they had Fionn as a house guest, and he organised a boar hunt. It had been foretold that Diarmaid would be killed by hunting the great boar of nearby Benbulben in County Sligo. Gráinne tried to stop him joining the hunt but he went and was killed; Fionn could have saved him but chose not to, to the dismay of his men.