Lably
Skip to content

Diarmait mac Cerbaill

6th century High King of Ireland

  • 10 min read
  • 5 chapters

Related on Lably

Through Fosterage and Monastery

While many later stories were attached to Diarmait, he was a historical ruler and his descendants were of great significance in Medieval Ireland.

Descendants of Niall

Diarmait was the son of Fergus Cerrbél, son of Conall Cremthainne, son of Niall of the Nine Hostages. Yet of Niall's own historicity there is little reason to doubt. His descendants quarrelled incessantly among themselves after the manner of most Irish dynastic families and had no cause to invent a common ancestry, since by unanimous testimony the high-kingship of Tara prior to Niall's days had not been the preserve of any one tribe or family. By the end of the fifth century, however, it was well on the way to becoming so. Niall's sons and grandsons proclaimed their intention of monopolising it to the exclusion of their western cousins by discarding the tribal appellation of Connachta and adopting the dynastic name Uí Néill, nepotes Néill. As a great-grandson of Niall, Diarmait and his descendants were counted among the Uí Néill, the name meaning "descendants of Niall".

The two great Southern Uí Néill dynasties of the midlands were the Síl nÁedo Sláine (the Seed of Áedo of Slane), kings of Brega in the east, and the Clann Cholmáin Máir (the Children of Colmán the Great) in Mide with their centre in the heart of modern Westmeath. The former are more prominent in the seventh century, but after the death of Cináed mac Írgalaig in 728 all the high-kings of the Southern Uí Néill come from the Clann Cholmáin except for a brief period between 944 and 956 when the king of Knowth, Congalach Cnogba, restored the high-kingship to the Brega line.

It is remarkable that the Síl nÁedo Sláine and Clann Cholmáin derive their origin, not directly from Niall Noígiallach, but from his great-grandson Diarmait mac Cerbaill. The annals date Diarmait's reign as high-king from about 544 to 565. The petty Uí Néill kings of Cenél nArdgail traced their ancestry to an uncle of Diarmait's, but never won the high kingship. Besides Colmáin Már and Áed Sláine, Diarmait had a third son Colmáin Bec, whose descendants, the dynasty of Caílle Follamain, ruled an area corresponding to the baronies of Fore, between Mide and Brega.

Diarmait's immediate origins are obscure and may arouse some suspicion. In spite of his patronymic (Latinised by Adomnán as filius Cerbulis) the genealogical tradition says that his father's name was Fergus, nicknamed Cerrbél or 'crooked mouth.' His grandfather Conall son of Niall was nicknamed Cremthainne (possibly denoting fosterage among the Uí Chremthainn of Airgialla), to distinguish him from his brother Conall Gulban, ancestor of the Cenél Conaill. The habit of giving the same name to different sons remained common among the prolific Irish princes until the sixteenth century.

Sign in to keep reading

4 more chapters are free with a Lably account.

More in Politicians and leaders