Fintan was the son of Niall Niamglonnach from Dún Da Benn, and the father of Cethern. And he came to avenge the honour of the Ulstermen and to take revenge for his son's death on the hosts. Thrice fifty was the number of their band, and they came with two spear-heads on every shaft, a spear-head on the point and a spear-head on the butt, so that they wounded the hosts alike with points and butts. They gave battle three times to the hosts and three times their own number fell by them, and there fell also all the people of Fintan mac Neill except Crimthann the son of Fintan who was saved by Ailill and Medb under a shelter of shields. Then the men of Ireland said that it would be no disgrace to Fintan mac Neill to evacuate the encampment for him and that his son Crimthann should be allowed to go free with him, while the hosts should withdraw a day's march to the north and he should cease to attack the hosts until such time as he should come to them on the day of the great battle when the four great provinces of Ireland should meet at Gáirech and Ilgáirech in the Foray of Cúailnge, as had been prophesied by the druids of the men of Ireland. Fintan mac Neill agreed to this and his son was set free to him. The encampment was evacuated for him and the hosts retreated a day's journey northwards again, checking and holding themselves back. And each man of Fintan's people and each man of the men of Ireland were found with the lips and nose of each of them in the teeth of the other. The men of Ireland noticed this and said: This is the tooth-fight for us, the tooth-fight of Fintan's people and of Fintan himself.
So that is Fiacalgleó Fintain.