During his captivity he was converted, and acquired a knowledge of the Celtic language. After six years of captivity, he had a dream in which he was commanded to return to Britain. He escaped, returned to Britain, then went to Gaul, and studied at Tours, Urins, and Auxerre.
He was guided by Saint Germain at Auxerre and went as his mission companion to Britain. Pope Saint Celestine I, at the recommendation of Saint Germain, entrusted Saint Patrick with the mission of converting Britain and Ireland. Patrick was consecrated in the city of Turin at the hands of Saint Maximus and shortly afterwards set out for the Irish mission. His chariot driver was Saint Odran, and Saint Jarlath was one of his spiritual students.
He and his companions landed at Wicklow Head sometime around 433, where they were attacked by the Druids. They went on to Dalriada, and erected a church at Sabhall. On Easter Sunday in 433, Patrick pleaded for the faith before King Leoghaire, and converted his brother, Conall, and Dubhtach, the chief bard. It was on this occasion that Saint Patrick is said to have plucked a shamrock from the grass, to explain by its triple leaf and single stem the doctrine of the Blessed Trinity. After this, Patrick was allowed to preach the faith throughout Ireland.
In 33 years he effectively converted Ireland. It is recorded that he consecrated no less than 350 bishops, and continued until his death to visit and watch over the churches he had founded in all the provinces of Ireland. When not engaged in the work of the sacred ministry, his time was spent in prayer and penitential austerities.
During his apostolate in Ireland he was subjected to frequent trials by the Druids and other opponents of the Faith, and no less than twelve times he and his companions were condemned to death. From all these trials he was liberated by Providence, and did not die until the conversion of Ireland was complete.
Saint Patrick died of natural causes around 461-464 A.D. at Saul, County Down, Ireland.