St. Patrick was born in 385 AD somewhere along the west coast of Britain. At age 16, he was captured and sold into slavery to a sheep farmer. He escaped slavery when he was 22 and spent the next 12 years of his life in a monastery.
During his 30s he had a dream that the voices of the Irish people were calling him to convert them to Christianity. So he decided to return to Ireland. Although there were already some Christians living in Ireland, St. Patrick was able to bring upon a massive religious shift to Christianity by converting people of power.
St. Patrick laid the groundwork for the establishment of hundreds of monasteries and churches that eventually popped up across the Irish country to promote Christianity.
It is believe he died in the 5th century on March 17, which is the day St. Patrick's Day is commemorated each year.