Cormac Mac Airt

Cormac was the son of Art and grandson of Conn Cétchathach, high king of Ireland. He succeeded his grandfather after his death. Cormac ruled during the time when Finn Mac Cumhaill was captain of the Fianna, the high king's personal bodyguards and the elite force of warriors during times of war.

Cormac Mac Airt was considered to be a great high king, ruling Ireland with wisdom and justice, because of which the Tuatha Dé Danann thought very highly of him.

Cormac married Eithne (probably Eithne Tháebfhota) and was the father of two sons: Cairbre Lifechair and Cellach. Cormac was also the father of two daughters, Gráinne (Grainne) and Ailbe Grúadbrecc (Ailbe of the Freckled Cheeks).

In the tale, titled Echtrae Cormaic (The Adventure of Cormac), which was found in several manuscripts, it tells of his journey into the otherworldly Tir Tairgire (Land of Promise).

Cormac met a warrior at Tara who had a branch with three golden apples. When the branch was shaken, beautiful, unearthly music could be heard. The warrior would only give the branch if Cormac would grant him three wishes; the high king agreed.

After a year, the warrior returned to Tara, and his first wish was Cormac's daughter, Ailbe. So the king gave his daughter to the nameless warrior. In the following month, the warrior returned with his second wish: Cairbre Lifechair, Cormac's son. Cormac readily agreed, so the warrior took Cairbre. When the warrior asked for Eithne, Cormac angrily refused to surrender his wife. So the warrior spirited Eithne out of Tara and escaped from pursuit, using his magic. The warrior enveloped the land with a strange mist, so Cormac became lost.

After various adventures, Cormac came upon a dun, where his host offered him hospitality. His host told the king that the pig he had on a spit could not be cooked until he could tell a story that was true. So Cormac recounted the event of what had happened to him, and how he lost his wife, daughter and son to a nameless warrior. At the end of the story, the roasted pig was ready.

However, it seemed that Cormac had a geis, because of which he couldn't dine until there was in the company of fifty. His host caused the king to fall asleep, so when he woke, he found himself seated with fifty warriors as well as his missing wife and children.

The nameless warrior introduced himself as Manannán Mac Lir. Manannán showed three pieces of a golden cup. It was the cup of truth: three lies will break the cup and three truths will restore the cup. So Manannán told the king that Eithne had slept with no other man since she had left Tara. His daughter Ailbe was still a virgin and his son Cairbre had not slept with any woman. So with three truths, the broken cup was magically restored.

Then Manannán gave the magic cup and branch to Cormac, but it had to be returned at the end of his reign. The next day the king and his family were returned to Tara. Cormac used the cup during his reign to determine falsehood from truth.

In the Tóraigheacht Dhiarmada agus Ghráinne (The Pursuit of Díarmait and Gráinne), though betrothed to Finn Mac Cumhaill, Gráinne was in love with the younger companion of the Fian captain, Diarmait Ó Duibhne. Her love for Diarmait caused serious harm to the friendship of two Fian warriors. Cormac and Angus Óg (foster-father of Diarmait) made an uneasy peace between Finn and Diarmait, where Finn married another daughter of Cormac. However, it ended in tragedy when Finn refused to heal Diarmait, who was mortally wounded by a wild boar. In some versions, the tale ended with Diarmait's death, while in other versions, Gráinne ended up marrying Finn. In one version however, Finn married Ailbe Grúadbrecc (Ailbe of the Freckled Cheeks) at the intervention of Angus Og, after Finn made peace with Diarmait.

Cormac became embroiled in a war against the Dananns when Cellach raped a niece of Angus Óg. Cellach was Cormac's nephew. During a battle, Cellach was killed and the king lost one of his eyes. This barred him from kingship. Without any choice, Cormac Mac Airt abdicated.

His son Cairbre Lifechair succeeded him as high king of Ireland. Unlike his father, Cairbre did not like the Fianna.