ABSTRACT
Firm historical information about Diarmait is scarce. The available annals, which may include some near contemporary material, but which were certainly augmented in subsequent centuries, suggest that his career was not a particularly successful one. Diarmait’s prominence in Irish history derives primarily from the fact that he was said to be the father of Colmán Már and Áed Sláine, the putative progenitors of the Clann Cholmáin Máir and Síl nÁedo Sláine. These were dynastic groups that rose to prominence in the seventh and eighth centuries, respectively, and were dominant among the southern Uí Néill (based in the Irish midlands), as well as assuming over kingship of the Uí Néill on many occasions. In consequence of his status as a common Uí Néill ancestral figure, Diarmait served as a suitable emblematic figure for later mythmakers to convey particular messages about their own times-messages that frequently dealt with the tensions between church and state. Possibly the earliest writer to adapt Diarmait to his own ends was St. Colum Cille’s biographer, Adomnán, writing at Iona around 700, who claimed that Diarmait was totius Scotiae regnatorem Deo auctore ordinatum (ordained by God as ruler of all Ireland).
