Schiller's Don Carlos was first suggested to Verdi in 1850 by the Paris Opéra. Verdi rejected the idea, but continued negotiations led to the composition and production of Les vêpres siciliennes in 1855. When the new director of the Paris Opéra, Auguste Perrin, approached Verdi in 1865 concerning a new work for Napoleon III's Universal Exhibition of 1867, Verdi had become tired of the intolerance of Italian theatergoers. Paris seemed to offer more creative potential, a stable company of singers and players, and a large budget. Verdi accepted Perrin's proposition, hoping to score a major success in grand opera.
After considering several librettos, Verdi decided on one by Joseph Méry and Camille du Locle that adapted the dramatic poem Don Carlos, Infant von Spanien, by Friedrich Schiller (1759-1805). However, Verdi felt that the story lacked the spectacle necessary for grand opera, and suggested the addition of the immense and colorful coronation scene in Act Three. No one has yet successfully explained why Philip should be crowned in the middle of his reign.
Such additions made the work run beyond the maximum time allowed by the Opéra, and numerous cuts were made during the eight months of rehearsals. (These sections remained unknown until 1969.) Finally, the original, five-act, French version of Don Carlos was performed at the Académie Impériale de Musique in Paris on March 11, 1867. A revised version in Italian was first staged on January 10, 1884, at the Teatro alla Scala in Milan.
Throughout the composition process, Verdi shaped the libretto to his liking, suggesting meters and occasionally writing lines and drafting scenes such the final one, in which Elizabeth makes her fateful decision. He also added the Philip-Inquisitor duet that is part of Schiller's play. In general the work, especially through the character of the Marquis de Posa, advocates freedom of thought; Verdi may have been reacting in part to Pope Pius IX's "Syllabus of Errors" of 1864, which denounces this very idea.
Conflicts of a political sort abound in Don Carlos, in which the titular hero is in love with Elizabeth de Valois, who has become the wife of his father, King Philip II, as the result of a political marriage. Furthermore, the Marquis de Posa, Don Carlos's best friend, is wanted by the Grand Inquisitor because he is a "freethinker." Philip discovers his wife's infidelity and must decide what to do about his son while the Grand Inquisitor asserts his power over him. According to Verdi, the climax of the opera is the auto-da-fé scene in Act Three.
The revised version sets an Italian translation by Angelo Zanardini of the revised libretto by Camille du Locle. Verdi and Zanardini dropped the entire first act, placing all of the action in Spain. One problem that results is that when we hear the "love theme" for Don Carlos and Elizabeth, returning in leitmotiv fashion, we have no context from which to make sense of it; it originally appeared in the abandoned first act. Also, the opening Prelude and Introduction of the original Act One provide important links to the beginning of Act Four.