Saint Patrick, the patron saint of Ireland, was born around 373-385 A.D. and is known for his missionary work in Ireland after escaping slavery. He was commissioned by Pope Celestinus to preach Christianity, baptizing thousands and famously using a shamrock to explain the Trinity. Patrick's death in 461 A.D. marked the flourishing of Christianity in Ireland, leading to significant cultural and religious legacies celebrated globally on March 17th.