There’s two ways of it. The one you know is where the king invited the boy to a feast at Emain Macha and released Cullain’s fierce guard hound when it was believed all had safely arrived. The boy came late and was attacked but he coolly dispatched the fierce dog with one blow of his hurley. Thereafter he promised to take its place to guard the smith. He became the Hound of Cullain, Cuchullain.
Slieve Gullion is the most mystic of Irish mountains, linked with Irish literature through the ‘Chase of Slieve Gullion’. It is associated with many Irish heroes of old, principally Cuchullain – and Cullain the smith to King Conor MacNessa whose name by proxy, the boy Setanta borrowed.
The one you don’t know is about a fairy on Slieve Gullion whom Cullain chased, for whatever reason we’re not sure. Anyway the fairy blinked his hound, so that when Setanta arrived a few days later, the dog attacked him, with fatal results for the hound. The rest’s the same!
The mountain may be named after him: alternative possible derivations are from the Gaelic word for ‘holly’, or then again, that for a water-course.
Cuchullain, Ossian, Finn MacCool, the Calliagh Berra, Deirdre, the children of Lir and many another legendary figure live still in the old tales told on its slopes. It is said that when the Calliagh first took up her abode on the mountain – that’s her house up there, in the souterrain beneath the north cairn, and her lake beside it – that hay grew almost to the summit. She was, however, so unsociable and nasty that people stopped cutting it rather than meet her. That’s the reason, of course, that heather now blankets the mountain.
I shouldn’t tell ye this, but we’ve got to know one another recently! On the mountain somewhere there’s a magic heather and a well of wisdom. Using them both, if we only knew the recipe, we could brew a marvellous ale that, once tasted, age could not touch us, nor sickness, nor death.