What part did Fianna Eireanna play in Irish history?

the original fianna were legendary warriors who fought to protect Ireland from various invaders, witches, demons etc. led by the great Fionn Mac Cumhail, and including the saga of Diarmuid and Gr�inne. they ended after the return from tir na n�g (the land of youth), after many centuries, of Ois�n, who falling from his horse instantly became a very old man and died. since then in the 19th and 20th centuries some groups used the name "Fianna" in an attempt to establish a sort of respectable cultural pedigree. most famous is Fianna Fail, irelands largest political party. the term fianna or fine just means warriors/soldiers or even more loosely, a tribe.