Cormac mac Cuilennáin (died 13 September 908) was an Irish bishop and the king of Munster from 902 until his death at the Battle of Bellaghmoon. He was killed in Leinster. Cormac was regarded as a saintly figure after his death, and his shrine at Castledermot, County Kildare, was said to be the site of miracles. He was reputed to be a great scholar and is credited with the authorship of the Sanas Cormaic (Cormac's Glossary) and the now-lost Psalter of Cashel, among other works. The reliability of some of the traditions concerning Cormac is doubtful. His feast day is September 14. Background The Ireland of Cormac's time was divided into small kingdoms or túatha, perhaps 150 in all, on average around 500 square kilometres in area, with a population of some 3000 each. In theory, but not in practice, each tuath had its own king, bishop, and court. Variations in size and power were very considerable. Groups of tuatha were dominated by one of their number, whose king was their collective ruler. Above these stood the five great provincial kingships whose names survive in the provinces of Ireland: Connacht, Leinster, Ulster, Meath, and Cormac's Munster. To these can be added the kings of the northern and southern Uí Néill. These last provided were the High Kings of Ireland, kings whose authority was an increasingly obvious political fact in Ireland of the 8th and 9th centuries. In Cormac's time the High Kingship was held by Flann Sinna of the Clann Cholmáin branch of the southern Uí Néill. In addition to these native Irish kings, Ireland had also seen Scandinavian and Norse-Gael kings establish themselves along the coasts during the Viking Age. The destruction of Viking settlements on the northern coasts by Flann's predecessor Áed Findliath, followed by much internal dissension, had weakened the Vikings, who were expelled from Dublin by Flann's allies in the year that Cormac became the king of Munster. Cormac belonged to a minor branch of the Eóganachta clan which dominated Munster in the 8th and 9th centuries. According to genealogies, he was a member of the Eóganacht Chaisil, the Cashel branch of the clan. This kin group was important, but Cormac came from a very minor branch. He was considered to be an eleventh generation descendant of Óengus mac Nad Froích and none of his ancestors since Óengus were counted as kings of Cashel. Cormac, as