True history and legend are intertwined when it comes to St. Patrick. There are many arguments over whether he was born in Wales, England or Scotland but at the time of his birth these places did not yet exist and the country was called Briton and was under Roman rule and latin was the language. His parents were also Roman so his given name was actually Patricus. Eventually he was ordained as a deacon, then priest and finally as a bishop. Pope Celestine then sent him back to Ireland to preach the gospel. Evidently he was a great traveller, especially in Celtic countries, as innumerable places in Brittany, Cornwall, Wales, Scotland and Ireland are named after him. Here it is where actual history and legend become difficult to seperate.
Patrick is most known the world over for having driven the snakes from Ireland. Different tales tell of his standing upon a hill, using a wooden staff to drive the serpents into the sea, banishing them forever from the shores of Ireland. One legend says that one old serpent resisted, but the saint overcame it by cunning. He is said to have made a box and invited the reptile to enter. The snake insisted the box was too small and the discussion became very heated. Finally the snake entered the box to prove he was right, whereupon St. Patrick slammed the lid and cast the box into the sea. While it is true there are no snakes in Ireland, chances are that there never have been since the time the island was seperated from the rest of the continent at the end of the ice age. As in many old pagan religions serpent symbols were common, and possibly even worshipped. Driving the snakes from Ireland was probably symbolic of putting an end to that pagan practice.
While not the first to bring Christianity to Ireland, it was Patrick who encountered the Druids at Tara and abolished their pagan rites. He converted the warrior chiefs and princes, baptizing them and thousands of their subjects in the Holy Wells which still bear that name.
According to tradition St. Patrick died on 17 March in A.D. 493 and was buried in the same grave as St. Bridget and St. Columba, at Downpatrick, County Down. The jawbone of St. Patrick was preserved in a silver shrine and was often requested in times of childbirth, epileptic fits and as a preservative against the evil eye. Another legend says St. Patrick ended his days at Glastonbury and was buried there. The Chapel of St. Patrick still exists as part of Galstonbury Abbey. There is evidence of an Irish pilgrimage to his tomb during the reign of the Saxon King Ine in A.D. 688, when a group of pilgrims headed by St. Indractus were murdered.
The great anxiety displayed in the middle ages to possess the bodies, or at least the relics of saints, accounts for a the many discrepant traditions as to the burial places of St. Patrick and others.
The Life of St. Patrick is a more accurate, historical account of his life, but it is a very long. For an account of St. Patrick's life written by him you can go to Confession of St. Patrick which is another long document.