On March 17, 461 A.D., Saint Patrick, Christian missionary, bishop and apostle of Ireland, dies at Saul, Downpatrick, Ireland. Today he is honored with the annual holiday of St. Patrick's Day.

Much of what is known about Patrick’s legendary life comes from the Confessio, a book he wrote during his last years. Born in Great Britain, probably in Scotland, to a well-to-do Christian family of Roman citizenship, Patrick was captured and enslaved at age 16 by Irish marauders. For the next six years, he worked as a herder in Ireland, turning to a deepening religious faith for comfort. Following the counsel of a voice he heard in a dream one night, he escaped and found passage on a ship to Britain, where he was eventually reunited with his family.

According to the Confessio, in Britain Patrick had another dream, in which an individual named Victoricus gave him a letter, entitled “The Voice of the Irish.” As he read it, Patrick seemed to hear the voices of Irishmen pleading him to return to their country and walk among them once more. After studying for the priesthood, Patrick was ordained a bishop. He arrived in Ireland in 433 and began preaching the Gospel, converting many thousands of Irish and building churches around the country. After 40 years of living in poverty, teaching, traveling and working tirelessly, Patrick died on March 17, 461 in Saul, where he had built his first church.

Since that time, countless legends have grown up around Patrick. Made the patron saint of Ireland, he is said to have baptized hundreds of people on a single day, and to have used a three-leaf clover–the famous shamrock–to describe the Holy Trinity. In art, he is often portrayed trampling on snakes, in accordance with the belief that he drove those reptiles out of Ireland. For centuries, the Irish have observed the day of Saint Patrick’s death as a religious holiday, attending church in the morning and celebrating with food and drink in the afternoon.

The first St. Patrick’s Day parade, though, took place not in Ireland, but the United States. Records show that a St. Patrick’s Day parade was held on March 17, 1601 in a Spanish colony under the direction of the colony's Irish vicar, Ricardo Artur. More than a century later, homesick Irish soldiers serving in the English military marched in Boston in 1737 and in New York City on March 1762. As the years went on, the parades became a show of unity and strength for persecuted Irish-American immigrants, and then a popular celebration of Irish-American heritage. The party went global in 1995, when the Irish government began a large-scale campaign to market St. Patrick’s Day as a way of driving tourism and showcasing Ireland’s many charms to the rest of the world. These days, March 17 is a day of international celebration, as millions of people around the globe put on their best green clothing to drink beer, watch parades and toast the luck of the Irish.