Cathal also appears as a character, not always portrayed sympathetically as in Aislinge Meic Con Glinne where he is possessed by a demon of gluttony, in a number of prose and verse tales in the Middle Irish language.
The contest for control of Leinster would play a major part in Cathal's reign, and indeed in relations between the Eóganachta and Uí Néill in the centuries which followed.
[9] Finally, in the vast province of Munster itself there were several respectable but peripheral dynasties, such as the Uí Liatháin (for whom see below), whose relationships with the Eóganachta were rather distant and ambiguous.
The earliest record concerning Cathal, although it does not explicitly name him, is in 715 when Murchad mac Brain Mut of the Uí Dúnlainge, the king of Leinster, led his inaugural raid against Cashel.
The Annals of Inisfallen, as partisan a southern record as the Annals of Ulster are biased towards the Uí Néill, give a different and less reliable report of the events in 721:The harrying of Brega by Cathal son of Finnguine, king of Mumu, and after that he and Ferga son of Mael Dúin, king of Temuir [Tara], made peace; and Ferga submitted to Cathal.
This defeat was recorded in the Cath Almaine, a poem about the battle of Allen, fought on 11 December 722, the feast of Saint Finnian of Clonard.
Much of the work is devoted to the story of the faithful bard Donn Bó, but the introduction provides a late view of the war:For a long time there was great warfare between Cathal son of Findguine, king of Leth Mogha, and Fergal son of Máel Duin, king of Leth Cuinn.
[18] With the Uí Néill kings no great threat during the reigns of Fogartach, Cináed and Flaithbertach, Cathal sought to extend his authority over Leinster.
The Cath Almaine claims that the dispute arose because Fergal mac Máele Dúin had been killed in defiance of the truce he had made with Cathal.
[20]In 733 Cathal raided the lands of the Southern Uí Néill, but was defeated and driven off from Tailtiu by Domnall Midi of Clann Cholmáin.
Cathal had more success against the neighbouring Clann Cholmáin Bicc, ruled by Fallomon mac Con Congalt, whom he defeated at the Hill of Ward.
However, the clerics of Armagh may have been well satisfied as the Annals of Ulster, in the entry following that which reports the meeting of Cathal and Áed Allán, say that the law of Patrick was in force in Ireland.
[23] Cathal Mac Finguine is a major character portrayed in the medieval satire Aislinge Meic Con Glinne as ruler of the Kingdom of Munster.
[24] Cathal is vying for the Kingship of Tara against the Kings of Ailech and in an effort to cement cordial relations he attempts courting Lígach, the daughter of Máel Dúin mac Máele Fithrich.
Fergal asks a scholar to place charms and heathen spells on the apples being sent by his sister to King Cathal, with the aim of bringing about his destruction.
His gluttonous actions are so terrible that a famine is caused and the people of Munster are brought low: "Cathal thereupon ate the apples, and little creatures through the poison spells were formed of them in his inside.
The Cork monastery may have been suffering from the famine Munster had been experiencing or may well have been aligned to the more ascetic form of Celtic Christianity which was less prominent in the North of Ireland than it was in the South at that time.
Mac Conglinne eventually manages to bargain his way to freedom when he claims he can cure King Cathal of his gluttonous possession that has brought Munster to its knees.
[25] Cathal is cured and promises Mac Conglinne: ‘He shall have a cow out of every close in Munster, An ounce for every householder, A cloak for every church, And a sheep from every house from Carn to Cork.
Munchin was very displeased to hear that, the symbol of his office, was being given up as a reward to Mac Conglinne and stated: "I declare, in the presence of God and of St. Barra, that if the whole country between Cork and its boundary were mine, I would sooner resign it all than the cloak alone."