Ernani is an operatic dramma lirico in four acts by Giuseppe Verdi to an Italian libretto by Francesco Maria Piave, based on the 1830 play Hernani by Victor Hugo.

Verdi was commissioned by the Teatro La Fenice in Venice to write an opera, but finding the right subject took some time, and the composer worked with the inexperienced Piave in shaping first one and then another drama by Hugo into an acceptable libretto.

As musicologist Roger Parker notes, the composer "intervened on several important points, insisting for example that the role of Ernani be sung by a tenor (rather than by a contralto as had originally been planned)".

Amongst other stipulations, he demanded the right to choose his own subject and his own librettist, and also to pay him directly, as well as refusing to accept the requirement that a full orchestral score be available in advance.

[4] David Kimbell notes one additional demand: He explains [to Mocenigo at La Fenice]—and this was rare at the time—that he began to compose only when the libretto was completed to his satisfaction because "when I have a general conception of the whole poem, the music comes of its own accord"[5]Once this agreement was settled upon, the next step was to choose a subject, something which took some time.

An unsolicited manuscript from the unknown Francesco Piave (who was La Fenice's resident poet and stage manager in addition to being a friend of Brenna, the company's Secretary) proposed an opera, Cromwell, based on Victor Hugo's play, and on which he had started work.

But I do insist on brevity because that's what the public wants..."[6] The Cromwell libretto arrived from Piave in pieces, and Verdi put it away until he had the complete version to work from.

However, when the composer and La Fenice's president met in Venice in late August, Verdi expressed some dissatisfaction at how the libretto had turned out.

I know that it would mean a great deal of trouble for the poet but my first task would be to try and compensate him... all he would have to do would be to condense and tighten up; the action is already there ready made, and it's all immensely good theatre.

[9] But the La Fenice directorate did approve the concept and the librettist was offered compensation, although he saved his Allan Cameron in reserve in case of mishap.

However, he compromised somewhat and, by the end of October, it appeared that the four voice types were to be soprano (Elvira), contralto (Ernani), tenor (Don Carlo), and baritone (de Silva), but after the acceptance of the libretto by the Venetian police, Verdi was able to hold firm and ultimately get what he wanted: a soprano, a tenor, a baritone, and – although Rosi was not an experienced enough singer – a bass in the role of de Silva.

Having heard one other potential tenor, Vitali, as a possible replacement, the composer presented an ultimatum: either be released from his contract or the company would engage Carlo Guasco in the role of Ernani.

With a premiere set for March, two final glitches were overcome: the bass Rosi had disappeared from consideration as de Silva but was replaced by Meini, who then withdrew because he found the part too low.

Verdi [ten years younger than the playwright] was part of that youthful audience to which the play Hernani is addressed.

I've been able to put my finger on so many works which wouldn't have failed if the pieces had been better laid out, the effects better calculated, the musical forms clearer, etc... in a word, if either the composer or the poet had been more experienced.

[11]In effect, Verdi is taking control over all aspects of the piece, which includes the condensation of the sprawling play into his four acts.

Rather than allow the librettist a free hand in composing his verses, "this would have perpetuated in a diminished form the word-music division that Verdi precisely wanted to get away from.

The composer's desire to take charge of every aspect of an opera implied that he had the power to decide what weight to give the text and the music, respectively, depending upon the "moment" of the action.

"[13] However, it was not all smooth sailing: due to Hugo's opposition, the first performances in Paris at the Théâtre des Italiens two years later required a change of title – to Il proscritto – and a change of characters' names: "The practice was followed in other cities where the names Victor Hugo and Hernani smacked of revolution.

The Teatro Regio di Parma, another company with the aim of presenting every Verdi opera, gave it in October 2005.

Ernani replies that he loves Elvira (Recitative: "Thanks, dear friends"; Cavatina: Come rugiada al cespite / "As the flower turns to the sun"), who is about to be married against her will to old Gomez de Silva (O tu che l'alma adora).

Ernani whispers to Elvira to prepare to flee, while Carlo starts talking with Silva about his rights for the Holy Roman Empire.

(Choir: "Si ridesti il leon di Castiglia" / "Let the lion of Castille awaken") The conspiracy is foiled when Carlo's attendants enter and surprise the conspirators.

Ernani asks for time to "sip from the cup of love" (Ascolta, ascolta un detto ancor/ "Listen, just one word...") but, cursed by Silva as a coward, Ernani keeps his oath and stabs himself in the heart (Trio with Silva: È vano, o donna, il piangere, è vano / "Your weeping is in vain, woman").

Noting that the dramatic structure of this opera "brought about a fresh consideration of the fixed forms of Italian opera, in particular an expansion and enrichment of the solo aria and duet together with a more flexible approach to the musical sequences that bind together lyrical pieces", Roger Parker continues by stating that of greatest importance was "Verdi's gathering sense of musical drama's larger rhetoric, his increasing control over the dynamics of entire acts rather than merely of entire numbers.

"[21] However, it is writer Gabriele Baldini (whose specialization was in English literature) who in 1980 points to one of the most significant aspects of Ernani's dramatic and musical structure, the concept of male vocal archetypes, something which is echoed in Budden's 1984 chapter on this opera.

[23] The baritone [the King, Don Carlo] "manages to draw somewhat closer, although indirectly and ambiguously",[23] but Baldini continues by noting that it the highest male voice [the tenor, Ernani] who "gets near a relationship which if not complete ... is at least reciprocated for long periods".