In the Ulster Cycle of Irish mythology, Furbaide Ferbend was the son of King Conchobar mac Nessa and Clothru, who was murdered — while pregnant with him — by her own sister, Medb, in a struggle for the kingship of Connacht. Furbaide was cut from his dying mother's womb and grew up determined to avenge her death.
The story
Years later, learning that Medb (by then queen of Connacht) bathed every morning in a pool on an island in Lough Ree, on the Shannon, Furbaide practised for months with a sling, stretching a cord between two stakes set at the exact distance to the island and firing stone after stone until he could strike an apple balanced on a post every time. When his aim was perfected, he loaded his sling with a piece of hard cheese and, from the shore, struck Medb in the forehead as she bathed, killing her instantly in payment for his mother's death.
Local tradition holds that Furbaide was afterwards buried in the great passage-tomb cairn atop Carn Clonhugh — now known as Corn Hill or Cairn Hill, the highest point in County Longford — and the dindshenchas (place-name lore) of the hill preserves his name in its older title, Carn Furbaide.