According to the ancient Roman historian Livy, the rape of the virtuous Roman noblewoman Lucretia by the Etruscan prince Tarquinius Sextus brought about the expulsion of the occupying Etruscans from Rome. The incident was subsequently described, with varying details, by the poet Ovid, Shakespeare (in a long narrative poem) and in 1931 by French playwright Andre Obey.

In 1946, English composer Benjamin Britten -- buoyed by the success of his first major opera, "Peter Grimes," a year earlier -- took on a commission for a chamber opera on the subject, premiered in the elegant setting of the Glyndebourne Festival, and designed to tour in small theaters in Britain and Europe.

Britten's "The Rape of Lucretia" gained wide critical acclaim early on. The opera requires only eight singers and 13 instrumentalists, which makes it ideal for the resident artists of Pittsburgh Opera, who will open a four-performance run in the intimate CAPA Theater. Despite its small forces, this is a deeply serious work, with a literate and beautifully crafted libretto by Ronald Duncan, based in large part on Obey's play.

The original 1946 cast included some of the best singers of the day. The great English contralto Kathleen Ferrier performed the title role. The role of the Male Chorus (a solo tenor) was taken, alternately, by Britten's life partner Peter Pears and Danish tenor Aksel Schiotz.

"The Rape of Lucretia" was recorded, in abridged form, by members of the original company in 1948, something unusual for a new opera at the time. A Broadway production, staged by Agnes De Mille, opened in December of that year, with Kitty Carlisle as Lucretia and Giorgio Tozzi as Tarquinius. It has been performed at least twice previously in Pittsburgh: at Duquesne University in 1996 and Carnegie Mellon in 1977.

In Britten's opera, the Male and Female Choruses set the scene and interpret -- or misinterpret -- the events in terms of Christian morality. The characters in the drama itself remain oblivious to them until the end, when all eight singers join in an epilogue asserting a Christian explanation. The opera was written shortly after the end of World War II, and the conflict exists on several levels: Romans vs. Etruscans, pagans vs. Christians, Nazis vs. the British. The main protagonists, Lucretia and Tarquinius, are outsiders in their own society: Lucretia a virtuous wife in a debauched society, Tarquinius a handsome prince unable to find satisfaction either with his willing whores or his unwilling victim. Lucretia kills herself even though her husband, Collatinus, has forgiven her.

There are varying interpretations of the ambiguous relationship between Lucretia and Tarquinius, possibly influenced by changing mores in the decades since the opera's premiere. Nancy Evans, Ms. Ferrier's alternate in the original cast, insisted that Lucretia was never attracted to her assailant. By contrast Janet Baker, a great Lucretia of the 1960s and '70s, told biographer Humphrey Carpenter, "If she weren't in danger from his sexuality she wouldn't be frightened. If she had been emotionally uninvolved, she wouldn't have felt guilty after the rape."

Resident artist Lindsay Ammann, who will be Lucretia in Pittsburgh Opera's production, disagrees: "I feel that Lucretia does not have any attraction to Tarquinius," she says. "She and Collatinus are absolutely in love. I feel she kills herself as a symbol. 'He has taken away the person that I am,' is what she believes. She will remain a beacon of purity for eternity. Her legacy is that she was chaste."

Amy Zorn, who sang Lucretia in Boston in 1982, sees the heroine as "a total victim," adding: "She kills herself because of shame. She feels damaged even though Collatinus insists that the shame is not hers."

There are exciting and beautiful arias for each of the principals: Tarquinius' ride across the Tiber portrayed with cinematic specificity by the tenor Chorus; Tarquin­ius himself revealing his insecurities as he enters Lucretia's bedroom in a baritone aria that approaches Italian bel canto; the ravished Lucretia expressing her misery in a metaphor of fresh vs. damaged orchids. It should also be noted that the rape itself is realistic and scary, relieved only by an abrupt cut away from the action to the evangelizing Choruses.

Critics Andrew Druckenbrod and Scott Mervis talk about music on "The Beat," available exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.