Colmán mac Léinín, the patron saint of the diocese of Cloyne, has been poorly served by historians in the past resulting in an inaccurate picture emerging which is only now being clarified in the light of new research. This study argues that he was an historical personage and suggests the following biographical details. Born during the first half of the sixth century, Colmán was a member of that branch of the Cattraige people who lived north west of Emly in Co. Limerick.  This people were closely associated with the Eóghanacht kings of Munster and Colmán¿s first career was as a member of the filid or bardic caste, probably in service with the Eóghanacht kings at Cashel. At this time Colmán composed a number of poems which survive, and these are among the very earliest written literature in Irish. As part of this service Colmán came to the attention of Cairpre Crom, the king of Munster, and the two men struck up a relationship which, after the saint experienced an adult call to the religious life, resulted in the king gifting the saint with several properties in Munster, principally that of Cloyne where the saint founded a monastery on virgin woodland in a bog island.  The saint is known to have taken part in King Cairpre¿s battles, and one major victory for the king was later attributed to a curse invoked by the saint on the king¿s enemies.  After the king died, around 580 AD, the saint became the focus of conflict among his family as some tried to reclaim the lands donated to Colmán while others defended the interests of the saintly monk.  Later generations of the descendants of this royal line continued to promote the cult of the saint after his death, which occurred in the early years of the seventh-century.

Under the patronage of Cairpre¿s descendants, the Eóghanacht Glennamnach, the monastery of Cloyne developed as a major centre of learning, specialising in law and perhaps poetry, while the cemetery where Colmán was buried became one of the principal burial places of the Eóghanacht kings. By the tenth century Cloyne was a major ecclesiastical city with a large population and impressive public buildings, one of which, the round tower, can still be seen. Although the Eóghanacht Glennamnach declined in power after the middle of the ninth century they continued to exercise local power over much of Co. Cork from their centre at Glanworth and appear to have continued to promote the cult of their patron saint. The extent of this cult can be seen in that of the paruchia of the monastery of Cloyne, which would seem to have covered more or less the area which later became the diocese of Cloyne. Although this diocese in its modern form only comes to light in documents of the 1140s there is some evidence that a territorial episcopate seated at Cloyne existed for some centuries before this, the extent of which probably equalled that of the later diocese. The long association of Colmán with Cloyne and its diocese was perpetuated in the 13th century with the building of a cathedral dedicated to the saint which replaced the older church at Cloyne.  In this context it is interesting to note that evidence of scholarly activity by Colmán is much more substantial than that attributed to Finbarr of Cork, and the traditional motto of University College Cork, ¿Where Finbarr taught let Munster learn¿ is hardly justified in the case of so nebulous a saint, particularly in contrast to Colmán of Cloyne whose value to Irish literature is proven.