Slemish (the mountain of Mis, a woman's name) is one of the most significant sites associated with Saint Patrick, who is generally credited with the foundation of the Christian church in Ireland.
About AD401 a raiding party returned to Ireland with a group of prisoners, including a sixteen year old Christian boy called Patrick or Succat, the son of a Romano-British landowner. It is popularly held that Patrick was sold as a slave to an Irish chieftan, Milchu, who lived in the Braid Valley north of Slemish. Milchu put him to work herding stock on Slemish. After six years Patrick made his escape and subsequently went to France, where he became a monk. In AD423 he returned to Ireland as a missionary.