The work Eithne, also known as Éan an Cheoil Bhinn (The Bird of Sweet Music), is considered by many critics to be the first full-scale opera written and performed in the Irish language. It was written by English/Irish composer Robert O'Dwyer.
The work saw its first performance at the Rotunda in Dublin during the Oireachtas na Gaeilge, a festival of Irish culture, in 1909.
The opera, based on a Gaeilge libretto written by Galway Reverend Thomas O'Kelly, covers three acts and includes in its complex plot the presence of stepbrothers, a divine descent to earth and the transformation of a queen into a bird.
References
Eithne (opera) Wikipedia(Text) CC BY-SA