Nabucco was Verdi's first great success. It is linked not only with the composer's history but also with the history of Italy. The "hit tune," the chorus "Va, pensiero," (Fly, my thoughts) became the unofficial hymn of Italian national liberation and reunification, and even today almost holds the status of national anthem. It was so strongly associated with Verdi that the crowds at his funeral procession spontaneously began to sing it as the cortege passed through the crowded streets of Rome.
Verdi at this time in his life was deeply discouraged and unhappy, due both to personal tragedy and to a lack of musical success, and it was the impresario Merelli who forced the libretto upon him. When Verdi tossed the text on a table, intending to have nothing to do with it, it opened at the words "Va, pensiero," and he read it, and then read the rest; at their next meeting, Merelli was able to persuade Verdi to continue his musical career with a setting of this libretto. So it's not that surprising that this one section has somewhat overshadowed the rest of the work, but the whole has as much to offer as this one part.
Abigaille is notorious as a killer role for the soprano daring enough to take it on -- the voices it is said to have ruined include that of Giuseppina Strepponi, Verdi's lover and later his wife -- but the rewards it offers are enough to tempt many a singer. The role has one of opera's most dramatic entrances, a beautiful aria and stunningly forceful cabaletta, a striking duet with Nabucco, and a death scene that can steal the show. Even Abigaille's recitatives are full of energy and virtuosic effect; one contains a two-octave leap to a high C. The role of Nabucco runs the gamut of emotions, from haughty belligerence to tender paternal love to insanity to humble faith in the God of the Hebrews, expressed in highly effective, if not yet completely individualized music. Zachary is the musical and dramatic predecessor to Procida in I Vespri Siciliani. Driven by patriotic fervor, he emerges in music that alternates between stirring exhortation, religious reflection, and hints of the single-minded ferocity that was to emerge again still later in Ernani and in the Inquisitor in Don Carlo.