Bélchú of Breifne is a warrior of Connacht

Connachta

The Connachta are a group of medieval Irish dynasties who claimed descent from the legendary High King Conn Cétchathach...

 in the Ulster Cycle

Ulster Cycle

The Ulster Cycle , formerly known as the Red Branch Cycle, one of the four great cycles of Irish mythology, is a body of medieval Irish heroic legends and sagas of the traditional heroes of the Ulaid in what is now eastern Ulster and northern Leinster, particularly counties Armagh, Down and...

 of Irish Mythology

Irish mythology

The mythology of pre-Christian Ireland did not entirely survive the conversion to Christianity, but much of it was preserved, shorn of its religious meanings, in medieval Irish literature, which represents the most extensive and best preserved of all the branch and the Historical Cycle. There are...

.

According to legend, he finds the Ulster

Ulaid

The Ulaid or Ulaidh were a people of early Ireland who gave their name to the modern province of Ulster...

 hero Conall Cernach

Conall Cernach

Conall Cernach is a hero of the Ulaidh in the Ulster Cycle of Irish mythology. He is said to have always slept with the head of a Connachtman under his knee. His epithet is normally translated as "victorious" or "triumphant", although it is an obscure word, and some texts struggle to explain it...

 close to death after his final combat with Cet mac Mágach

Cet mac Mágach

Cet mac Mágach is a Connacht warrior in the Ulster Cycle of Irish Mythology. He had a rivalry with the Ulster warrior Conall Cernach.In some myths, he is said to be the brother of Conall's mother, making him Conall's uncle....

, takes him home and tends to his wounds, intending to fight him when Conall is fit enough. As Conall recuperates, Bélchú regrets this honourable behaviour and tells his three sons to kill Conall as he sleeps in his sickbed. Conall overhears and makes Bélchú take his place in the bed, so when the sons arrive, they kill their father instead. Conall then kills the three sons, and takes all four heads home. The site of the conflict is now the modern-day village of Belcoo

Belcoo

Belcoo is a small village and townland in County Fermanagh, Northern Ireland, 10 miles from Enniskillen. It is on the County Fermanagh/County Cavan border beside the village of Blacklion in the Republic of Ireland...

, on the border of Counties Cavan

County Cavan

County Cavan is a county in Ireland. It is part of the Border Region and is also located in the province of Ulster. It is named after the town of Cavan. Cavan County Council is the local authority for the county...

 and Fermanagh

County Fermanagh

Fermanagh District Council is the only one of the 26 district councils in Northern Ireland that contains all of the county it is named after. The district council also contains a small section of County Tyrone in the Dromore and Kilskeery road areas....

, which is named after Bélchú.