St Patrick was a missionary and bishop who played a pivotal role in bringing Christianity to Ireland. Born in the late 4th century, most likely in Roman Britain, he was kidnapped by raiders at 16 and taken to Ireland as a slave. During his captivity, he deepened his Christian faith. After escaping, he had a vision in which he saw the people of Ireland calling him back to spread Christianity. He returned as a missionary, using the three-leafed shamrock to explain the Holy Trinity, which is why the shamrock remains a symbol of Ireland and Patrick. His efforts led to the conversion of many Irish people to Christianity; the Irish, in turn, led medieval missions to Britain and across Europe.
St Patrick’s feast day (17 March)—known as St Patrick’s Day—is celebrated by many Christian denominations. It is now a holiday celebrated across the world.