Saint Patrick's day only became a recognized feast day in the early 17th century. However, it's development and traditions took various forms of influence. Outside of knowledge of Saint Patrick as being perhaps the most important person in bringing Christianity to Ireland, little else is known. He probably was a British-Roman missionary who migrated from Britain in the 5th century CE, perhaps in the 430s when Rome's grip on Britain had faded. The work, <i> Declaration </i>, dated to this period, may have been written by him and provides the most detail on his life. It is not even clear if Patrick was his name, as other possibilities have been suggested such as Magnus. There is also the tradition of Palladius being the first bishop of Ireland, recorded to be around 431. He may have been a figure conflated with Patrick in later traditions, where Palladius and Patrick were combined into one figure.
Tradition holds he was taken captive as a teenager by Irish pirates from his native Britain. He eventually escaped but after some time he saw a vision and came back to Ireland to be a missionary. When he came back, he became active in baptizing and spreading Christianity. Interestingly, an early 7th century letter written by Columbanus, an Irish missionary, states that Christianity came to Ireland via Palladius. Works by Tírechán, writing later in the 7th century, then begin to attribute Christianity brought to Ireland via Patrick. The writer refers to <i>Book of Ultán</i>, which could be a missing or lost source regarding Patrick, as this work no longer survives. Many of the conversion stories mimic other conversion stories found in the late Roman Empire, suggesting that many of the stories were borrowed and attributed to Patrick or even that the stories were combined in relation to Patrick .