Eochaid mac Eirc

In the medieval Irish invasion-cycle tradition Eochaid mac Eirc, son of Erc son of Rinnal of the Fir Bolg, became High King of Ireland after overthrowing Fodbgen. He is presented as a dynastic/royal figure who ruled for ten years and whose reign ended when the Fir Bolg were defeated by the Tuatha Dé Danann at the first Battle of Magh Tuiredh. He is said to have been married to Tailtiu, after whom he named his capital (Tailtiu/Teltown).

Medieval sources and the supplied summaries provide no physical description of Eochaid; he is attested through genealogies, king-lists and narrative actions (kingship, festival foundation, burial). Tradition records that he was buried under 'Eochy's Cairn' but gives no bodily details.

Sources attribute to his reign certain favourable conditions — "no rain fell during his reign, only dew, and there was a harvest every year" — and credit him as "the first king to establish a system of justice in Ireland," framing him as a law-giver and ritual-political founder rather than as a supernatural agent. In accounts of his death the Tuatha Dé Danann's druids are said to have hidden sources of water by magic during the battle, leaving Eochaid overcome by thirst; he was subsequently found and killed by The Morrigan. These narrative elements depict his authority and vulnerability within a world where martial and magical forces determine sovereignty.