Patrick was the most important missionary but one man did not convert Ireland, with its decentralised politics and poor communications in a single lifetime. The conversion of Ireland was a long drawn out process. Christianity did not impose itself on Ireland, it adapted to Irish circumstances. Celtic gods and goddesses became Christian saints, pagan sites became church sites, holy wells became sites of Christians worship and important churches were often located closed to important political sites.

Patrick was born in Carlisle in north west Britain, but when he was a boy he was captured by Irish traders and taken to Ireland as a slave tending sheep. After about six years he escaped from his captors and travelled to Gaul (France) where he trained to become a priest. After working in Gaul and in Britain he is said to have been told in a vision to return to Ireland and convert the Irish to Christianity. Between the time of his arrival in 432 A.D. until his death in 461 A.D., he persuaded all the kings of Ireland to convert.