When Patrick was 16 years old, he was carried off by Irish marauders to Ireland and forced to live in slavery.  He served as a slave shepherd for six years.  He saw visions urging him to escape and he did so, fleeing to Gaul (France).

Once in Gaul, he became a monk.  Strangely enough, he was appointed bishop of Ireland and so he returned to the land that had once enslaved him.  Patrick is known for teaching the Irish about the Holy Trinity by comparing it to the shamrock.  The Holy Trinity is three (Father, Son and Holy Spirit) in one just as the shamrock has three petals on one stem.  Thus the shamrock became the symbol for St. Patrick's Day celebrated on on March 17.