At around the age of fifteen, St. Patrick was captured by Irish pirates and taken to Ireland as a slave. There he was forced to tend and care for sheep on the what was then a very pagan island. When he turned twenty, he heard God tell him to go to the coast in a dream. There he found some sailors who took him back to Britain where he was reunited with his family. A few years after returning home however, St. Patrick had a vision of an Irish man who gave him a letter that read: "We appeal to you, holy servant boy, to come and walk among us". With this, St. Patrick immediately began studying for the priesthood, and once he was ordained, he traveled back to Ireland to preach the Gospel.
In Ireland, St. Patrick converted thousands of people and began to build churches across the country. He would often use shamrocks to explain the Holy Trinity and he continued to convert all of Ireland for the next 40 years.