Saint Patrick’s Day, feast day (March 17) of St. Patrick, patron saint of Ireland. Born in Roman Britain in the late 4th century, he was kidnapped at the age of 16 and taken to Ireland as a slave. He escaped but returned about 432 to convert the Irish to Christianity. By the time of his death on March 17, 461, he had established monasteries, churches, and schools. Many legends grew up around him—for example, that he drove the snakes out of Ireland and used the shamrock to explain the Trinity. Ireland came to celebrate his day with religious services and feasts. Saint Patrick’s Day is celebrated on Wednesday, March 17, 2021.