Erismena

Erismena is an opera in a prologue and three acts by Francesco Cavalli. It was designated as a dramma per musica. The Italian libretto was by Aurelio Aureli, the only work by this writer for Cavalli.

Erismena is the first full-length opera known to have been translated into English and may have been first performed in England in 1674.

It was first performed in Venice at the Teatro Sant 'Apollinare on 30 December 1655 with further performances between that date and 28 February 1656. Cavalli revised the work in 1670. Both versions have survived as well as one with an English translation, also dated to the 17th century.

Pier Francesco Cavalli: L'Erismena - Oakland Symphony Orchestra - 'Sung in English

A manuscript score of Erismena, with English libretto, is the oldest surviving opera score in England, dating from the 1670s. The score was in a private library until 2008. A public subscription raised ₤85,000 to donate the score to the Bodleian Library, Oxford, after export of the score had been blocked by the British Reviewing Committee on the Export of Works of Art. The manuscript has a unique allegorical prologue, with characters who do not feature in the opera; this is believed to indicate that the version was performed, or intended to be performed, for a Royal audience.

...
Wikipedia