The most important text the regarding the family of Finn is Fotha Catha Chnucha, as it is contained in the ancient parchment Lebor na hUidre, dated to the 12th century. Otherwise, the next most important tract is the Macgnímartha Finn copied in a 15th-century manuscript. According to the Fotha Catha Chnucha, Cumhall mac Trénmhoir was son of a petty king, and served the High KingConn Cet-Chathach "of the Hundred Battles". Cumhall was also Conn's half-uncle, his mother being the mother of Conn's father,. Cumhall became suitor for the hand of Muirne Muncaim "of the fair neck", daughter of the druidTadg mac Nuadat, but Tadg refused him, so Cumhall forcibly carried away Muirne in elopement. ;In-laws In Fotha Catha Chnucha Cumhall's wife was the granddaughter to Nuadat who was a druid to king Cathair Mór, but she was granddaughter to Núadu of the Tuatha Dé Danann according to a passage in the Acallamh na Senorach. Also where the former work gives Almu daughter of Becan as Nuadat's wife, the latter treats Almha the daughter of Brecan as a virgin daughter who bore Cumall a son then died in childbirth. ;Siblings Cumhall had a brother, Crimmal mac Trénmhoir, who was an ally of Fionn.
Battle and death
Tadg, slighted by Cumall's sweeping away his daughter, appealed to Cumall's lord, Conn of the Hundred Battles, and Conn gave choice of either relinquishing the daughter or suffer banishment. Cumall refused to give up his wife, and Conn made war against Cumhall, and Cumhall was killed by Goll mac Morna in this Battle of Cnucha, located at what is today Castleknock. Goll then took over leadership of the Fianna, as explained in the Magnímartha Finn. Cumhall's wife Muirne was already pregnant with his son, Fionn, and Muirne's furious father Tadg not only refused to accept her back, but ordered her burnt to death. Cumhall's wife however seeks Conn's protection, and in exile she delivers a child which she names Demni. Demni later became Finn. Cumhall is reputed to be buried within the grounds of Castleknock College, supposedly under a hill upon which an old water tower now stands.
Parallels
Attempts to connect Cumhall with Camulus, a Celtic god of war known from Roman-era inscriptions, are now largely rejected. Old Irish cumal means "female slave", and it is possible that a noble father was invented for Fionn to obscure an ignoble origin. Alternatively, some early texts call the hero "Fionn mac Umaill", which may indicate his father's name was originally Umall.
