About the work
Demetrio is a three-act opera seria on a widely set libretto by Pietro Metastasio — also known under the titles Alceste, Cleonice or Demetrio, rè della Siria — first set by Antonio Caldara in Vienna in 1731. Niccolò Jommelli's setting premiered in spring 1749 at the Teatro Ducale in Parma, with the celebrated castrato Gioacchino Conti, known as "Gizziello", in the title role of Alceste.
Plot
Since her father's death, Cleonice has ruled Syria as queen and is expected by her people to choose a husband. She loves the shepherd Alceste, missing since a battle, whom her counsellor Olinto fears in vain as a rival. When Alceste unexpectedly returns and is made a general, Cleonice refuses to be forced into naming her choice — until Alceste turns out to be the prince Demetrio, thought dead, who can rightfully share the throne with her.
Cultural significance
Jommelli reworked the Parma score in 1751 for the Real Teatro del Buen Retiro in Madrid and again in 1753 for the Mannheim court theatre, adapting the opera to three different European courts. The premiere cast, led by the internationally celebrated soprano castrato Gizziello, reflects the importance Parma attached to the production.