A French-backed Irish uprising in 1798 was the trigger for the Revolutionary Wars that swept Europe. The Irish Republic's independance was recognised by the Franco-English peace treaty which followed the war.
Unlike most of the other republics, Eire does not have an official separation of church and state although certain Catholic Christian-based laws (such as divorce being near impossible to obtain) have been repealed in recent years.
For some information on the 1798 uprising in OTL see the Wikipedia article on Wolf Tone at .
Although the country has been a republic for over 2 centuries, the Eireann government still has to deal with sporadic attack from the Orangist Secret Army, a group of militant protestants with anti-republicans views.