Battle of Gabhra

When Cairbre, son of Cormac Mac Airt, became high king of Ireland, he wanted to break the power of the Fianna. Cairbre believed that the Fianna had become too powerful and arrogant.

Cairbre accepted the marriage between Sgeimhsholas, his daughter, and Maolsheachlainn O'Faolain, a prince. Finn demanded from the high king that he had to allow him to sleep with Cairbre's daughter before the marriage took place, or pay a large tribute to the Fianna.

Cairbre conspired with provincial kings from Ulster and Leinster to destroy or disband the Fianna. He raised a huge army to face the Fianna. Munster was the only province to support the Fianna.

It was Cairbre who provoked the war with the Fianna by killing Ferdia, the servant of Finn Mac Cumhaill.

There was also a split among the Fianna. Once again, Goll Mac Morna opposed the Clan Baiscne, siding with the high king.

The battle took place at Gabhra, in Leinster. Fierce fighting erupted with the Fianna; the Fianna were heavily outnumbered. Cairbre and Oscar, the son of Oisín, fought in a single combat, and Oscar killed the king. Oscar was also dying when his father found him covered with countless wounds. Weeping, Oisín and Caílte bore Oscar's body away.

According to this tale (Cath Gabhra or "The Battle of Gabhair"), five warriors murdered Finn at Garristown (Gabhra). While in the Aided Finn (The Violent Death of Finn), Aichlech Mac Dubdrenn killed Finn in battle at Ath Brea (Ford of Brea).

Casualties were extremely high on both sides. Only twenty Fian warriors survived the battle. The Fianna was defeated and the power of the Fianna was broken in Ireland.

Caílte Mac Ronan and Oisín were the only two surviving heroes of the Fianna.