For the first draft of the libretto of Un ballo in maschera (1859), Giuseppe Verdi drew his inspiration from the grand-opéra Gustave III by Auber, an opera performed for the first time in Paris in 1833 that depicted the assassination of the King of Sweden. However, censorship, first in Naples and then in Rome, intervened and imposed heavy modifications. Perhaps because it was too demanding, Verdi showed no intransigence with the requests coming from Naples and refused to alter the librett...