King Henry VIII began his own church in England (I forget which century) in protest because he wanted to divorce his wife and marry his mistress. The pope wouldn't allow it, so he outlawed Catholicism in England and created the Anglican church and required his subjects to belong to it. That way he could divorce and remarry as he wished. The Episcopalian church here in America is an offshoot from Anglicanism.
That's a pretty rough, rudimentary synopsis of the history, but I just couldn't let you go on thinking it was the Catholics who invaded Ireland :-)
So was the era that these Irish men died for wearing green, was under Christian rule?
Very good synopsis !