In the 5th century, there was a man know as St. Patrick, the "Apostle of Ireland".   

Patrick was born in Great Britain under the rule of the Roman Empire.  But when Patrick was 16 years of age the Roman Legions left Britain because of the heathen hordes of Visigoths, Ostrogoths, Vandals and the Huns were overrunning their borders.    

Britain was then left unprotected and soon attacked by pirate raiders form Ireland.  Young Patrick was capturedThe Emerarld Isle where Patrick evangelized and taken to Ireland and there sold as a slave.  At that time Ireland was ruled by the Druids, who practiced human sacrifice and for six years Patrick herded animals for a Druid chieftain.

Patrick wrote in his Confession: 
"But after I came to Ireland---every day I had to tend sheep, and many times a day I prayed---the love of God and His fear came to me more and more, and my faith was strengthened. 

"And my spirit was moved so that in a single day I would say as many as a hundred prayers, and almost as many in the night, and this even when I was staying in the woods and on the mountains; and I used to get up for prayer before daylight, through snow, through frost, through rain... There the Lord opened the sense of my unbelief that I might at last remember my sins and be converted with all my heart to the Lord my God who...comforted me as would a father his son."

Patrick also had a dream that he wrote about:
"One night I heard in my sleep a voice saying to me: `It is well that you fast, soon you will go to your own country… See, your ship is ready.'  And it was not near, but at a distance of perhaps two hundred miles...Then I took to flight...I went in the strength of God who directed my way...until I came to that ship."

Patrick eventually made his way back to Britain and was reunited with what was left of his family.  But when Patrick was 40 years old he had a calling from God to now go back to Ireland as a missionary for Christ.  In his Confession, Patrick wrote:

"In the depth of the night, I saw a man named Victoricus coming as if from Ireland, with innumerable letters, and he gave me one and while I was reading I thought I heard the voice of those near the western sea call out: 'Please, holy boy, come and walk among us again.'  Their cry pierced my very heart, and I could read no more, and so I awoke."

This time Patrick returned to Ireland confronting the Druids of their vile sin and converting thousands to Christ, including some influential Chieftains. 

Three leaf clover: The symbol of IrelandThe three-leaf clover became identified with Patrick as he would use that to help the people understand the Trinity of the Godhead.

The Druids tried to ambush and kill Patrick nearly a dozen times:
"Daily I expect murder, fraud or captivity, but I fear none of these things because of the promises of Heaven."

Baptizing 120,000, Saint Patrick founded 300 churches.  Saint Patrick "found Ireland all heathen and left it all Christian."

St. Patrick wrote:
"Patrick the sinner, an unlearned man to be sure.  None should ever say that it was my ignorance that accomplished any small thing, it was the gift of God."

In the next century, Irish missionaries sailed back to Europe and evangelized the heathen hordes which had overrun the Roman Empire.