Diarmait mac Tommaltaig

Who was Diarmait mac Tommaltaig?

Diarmait mac Tommaltaig was a king of Connacht from the Uí Briúin branch of the Connachta. He was the great-grandson of Indrechtach mac Muiredaig Muillethan, a previous king. The death of his father Tommaltach mac Murgail is recorded in the annals where he is called king of Mag nAi. He succeeded his brother Muirgius mac Tommaltaig. He was of the Síl Muiredaig sept of the Uí Briúin. He ruled from 815 to 833.

His brother had been a successful king who built up the local power of Connacht. Diarmait was confronted with opposition upon his succession. In 816 he defeated the Uí Fiachrach Muaidhe and sacked Foibrén in the territory of Grecraige. The annals point out that many common people were killed in this attack.

Then in 818 he imposed his authority over the Uí Maine with a victory at the Battle of Forath in the territory of the Delba Nuadat. Their king Cathal mac Murchada was slain. Máel Cothaid mac Fogartaig of the Síl Cathail sept of the Ui Briun is listed with Diarmait as victors in this battle and they are called Kings of the Uí Briúin, implying Diarmait may have shared his rule at first.