St Patrick's Day Tuesday 17th March.

Saint Patrick, (born in Britain) is the patron saint and national apostle of Ireland. He was an atheist through his childhood but convinced after a harrowing experience that it was the Lord who protected him and delivered him safely home. St Patrick received his call to spread the gospel in Ireland.
St Patrick was credited with successfully spreading Christianity throughout Ireland (which was largely pagan) —hence the Christian celebration of his life and name.