St. Patrick was actually a Roman by the name of Maewyn Succat, born in 387 AD in either Banwen, Wales (most likely) or Kilpatrick, Scotland.
At the age of 16 Maewyn was captured by Irish raiders and sold as a slave to the Irish chieftan Milchu of Dalriada.
For the next six years Maewyn tended his Irish slave master's sheep and pigs in the Braid valley of Ireland, where he worked the dogs and learned the Celtic language.
After six years of forced service, Maewyn ran away from his master and his flocks, heading 200 miles to the coast. There he stumbled on a ship from Gaul that was loaded with large dogs assembled by dog dealers bent on shipping them to the continent, where they were to be used against wild animals and gladiators in the Roman arenas.