Saint Patrick (b. 387 – d. 461) was born in Roman Britain. When he was fourteen or so, he was captured by Irish pirates during a raiding party. He was taken to Ireland which, at the time was a land of Druids and pagans, where he was sold into slavery.
When he was 20, he escaped after having a dream from God in which he was told to leave Ireland by going to the coast. There he found some sailors who took him back to Britain, where he was reunited with his family.
After studying and becoming a priest, he returned to Ireland on March 25, 433. For 40 years, he preached and eventually converted all of Ireland to the Christian faith. He often used shamrocks (not four leafed clovers) to explain the Holy Trinity. He is well known for having composed this prayer.
The Breastplate of St. Patrick
Christ be within me, Christ behind me, Christ before me.
Christ beside me, Christ to win me, Christ to comfort and restore me.
Christ beneath me, Christ above me, Christ inquired, Christ in danger,
Christ in hearts of all that love me, Christ in mouth of friend and stranger.