The Patron Saint of Ireland, that we all know today as St. Patrick, was not actually born in Ireland.  His real name was Maewyn Succat and was believed to be born in Roman England in the later half of the 4th century.  He was kidnapped by Irish bandits at a young age and taken back to Ireland to be sold for slavery.  After 6 long years he finally escaped and returned to Britain to join a monastery were he would eventually become a bishop.  It came to him in a dream, that the Irish were calling him back to tell them about God.  He spent most of his remaining years converting Gaelic Irish, who were mostly pagans, to Christianity and setting up churches, schools, and monasteries across the country.  It is said that he used the shamrock to explain the concept of trinity - the Father, the Son, and the Holy Spirit.  Because no one is sure of the exact day he was born, St. Patrick's Day is celebrated on the day he died, March 17th, 461 AD.  

St. Patrick statue