“Oisin fell in love with Niamh, a Celtic goddess and one of the queens of Tir na Nog – the land of eternal youth.

Oisin went to live with her in Tir na nOg and stayed there for several hundred years, never ageing and retaining all his youth and strength.

Eventually, he got homesick so Niamh gave him permission to return to Ireland on condition that he remained sitting on his magical horse at all times and did not touch the ground, even for a second.

His return to his native land was a disappointment for him because the friends and Fianna warriors he had known had been dead for centuries. He felt like a stranger in his native land.

He decided to return to Niamh but before he could do so, he saw a man struggling to lift a huge stone. Oisin stopped to help but as he strained to lift the stone, the strap on the saddle broke and he fell from the horse.

As soon as he touched the ground, he began to age rapidly, turning into a feeble old man.

As Oisin lay there dying, St Patrick walked by and stopped to talk. The discussion turned to the relative merits of their two religions and civilisations.

St Patrick gets the better of the debate. Oisin dies and St Patrick lives on, symbolizing the triumph of Christianity over the pagan gods of the Celts.”  see the debate recreated with axes at the St. Paddy’s Brawl

https://theknightshall.com/events-list/.