Irish myth. "The Sorrow of Deirdre," or "The Fate of the Sons of Usnech"
Son of Usnech and nephew of Conchobar mac Nessa, king of Ulster, Naoise fell in love with Deirdre, the wife of Conchobar. He ran off with her to Scotland with his two brothers, only to be lured back by Fergus mac Ruath. Fergus thought he was on a mission of peace, but when he returned Naoise and Deirdre to Ulster, Naoise and his brothers were slaughtered by Conchobar.
In her grief, Deirdre threw herself from Conchobar's chariot, and was crushed underneith. The lovers were buried in the same grave.
This tale, one of the Three Sorrows of Storytelling, is thought to be a very early version of what would become both the Tristan and Iseult and Lancelot and Guenevere romances.