Duach Ladhgrach was a legendary High King of Ireland. The office of High King of Ireland (Irish: Ard Rí Érenn) was in origin a pseudohistorial construct of the eighth century that placed a king of all Ireland atop the fragmented pyramid of kingship that actually existed at that time. ...
He and Airgeatmhar had killed Ailill Finn, who was then High King, only for Ailill's son Eochaid to hold onto the kingship. Eochaid witheld their attacks, and tried to discuss peace with Duach. Duach, however, betrayed and murdered him, and Airgeatmhar took the kingship. Duach later overthrew Airgeatmhar with the aid of Eochaid's son Lugaid Laigde, and took the throne himself. Airgeatmhar, son of Sirlám, was a legendary High King of Ireland. ... Ailill or Oilioll Finn, son of Art mac Lugdach, was a legendary High King of Ireland. ...
Airgeatmhar, son of Sirlám, was a legendary High King of Ireland. ... The High Kingship of Ireland was a pseudohistorical construct of the eighth century AD, a projection into the distant past of a political entity that did not become reality until the ninth century. ...
Duach is said to have pulled out the eyes of his younger brother, Deadha, because he dared to try to to come between Duach and the throne, hence the epithet Dalladh, "blindness," applied to Deadha.