Vincenzo Bellini (November 3, 1801 – September 23, 1835) composed this 2-act opera seria, La Straniera (The Foreign Woman.) Libretto was written by Felice Romani based on "l'Etrangère" by Victor-Prévot and Vicomte d'Arlincourt. The opera was premiered in Milan, Teatro alla Scala, February 14, 1829. The setting is in Brittany in the 14th century.
The opera La Straniera was devised by Bellini and Romani from the historical events of the life of Philip II of France who married the Danish princess Ingeborg sometime in 1193. For unknown reasons, Philip had the marriage annulled right after the wedding. He then sought to marry Marguerite, daughter of the Count of Geneva. Marguerite, in turn was kidnapped by Thomas I of Savoy who married her instead. After 3 years, Philip remarried Agnes of Merania, the 'la straniera' in the opera. Denmark continued to complain about Philip's treatment of Ingeborg, until Pope Innocent III required Philip to take her back, else he'll be excommunicated with bigamy. There wasn't any need for the threat since Agnes died in 1201.
Scene 1. Vestibule in the Castle of Montolino
Arturo is engaged to Isoletta, daughter of Montolino, but Arturo's does not love his fiancée, but the outcast stranger, Alaide. Osburgo promises Isoletta's father that Arturo will marry Isoletta.
Scene 2. Interior of a Cottage
Arturo visits Alaide, but Alaide does not want Arturo to share her misfortunes.
Scene 3. A Forest
Osburgo spies Alaide. Valdeburgo and Alaide recognize each other, making Arturo jealous. Valdeburgo begs Arturo to leave.
Scene 4. A Remote Spot
Osburgo tells Arturo that Valdeburgo and Alaide are lovers. Arturo challenges Valdeburgo and they fight. During the fight, Valdeburgo is wounded and falls into the lake. Alaide explains to Arturo that Valdeburgo is her brother. Arturo plunges into the lake to save Valdeburgo but Osburgo's men find Alaide with Arturo's bloody sword and without due investigation, arrest her.
Scene 1. A Grand Hall
Osburgo accuses Alaide of Valdeburgo's murder. At the trial, Alaide swears her innocence but refuses to reveal her identity or give evidence. Arturo tries to save Alaide by confessing, but the court condemns them both. Valdeburgo returns alive. The court is forced to release Alaide, but still demand to know her identity. She reveals her face only to the judge.
Scene 2. The Forest
Veladeburgo persuades Arturo that he must forget Alaide and marry Isoletta.
Scene 3. The Vestibule of the Chapel of the Knights of Malta
The wedding ceremony begins. Isoletta stops it knowing that Arturo does not love her. Alaide appears and persuades them to go through with it. Alaide reveals her identity, that she is actually the exiled queen, and faints. Arturo kills himself.
The Da Capo Opera Manual by Nicholas Ivor Martin, 1997
The Grove Dictionary of Music and Musicians, 2nd Edition, edited by Stanley Sadie (2000)