In August 1791, Mozart was commissioned to compose an opera celebrating the coronation of Emperor Leopold II as King of Bohemia at Prague. The coronation was to take place in early September, leaving Mozart with little time to complete the work. Under pressure, Mozart finished the opera in just 18 days, completing some parts in the carriage on the way to the Prague premiere.
The opera, La Clemenza di Tito, is a setting of an old libretto by Metastasio, reworked by Caterino Mazzola to reflect the sensibilities of the day. It tells the story of the betrayal of the Roman Emperor Titus and his willingness to pardon those who conspire against him -- even Sesto, who attempts to assassinate him. La Clemenza is an opera seria or serious opera, as opposed to opera buffa or comic opera; Mozart, however, adds some opera buffa elements to La Clemenza, including a number of ensemble finales. Ultimately, the opera is a rather austere Mozartean creation, with its relatively simple melodies, spare orchestral writing, and short numbers. The opera lacks arias in many of the conventional places, giving full-length arias only to the two principal characters. The aria texts themselves are less florid and more forthright than in Metastasio's original. Perhaps Mozart was not terribly inspired by the libretto or by the occasion; his talent was fired by the human dramas of the da Ponte libretti, not by Metastasio's stock characters. However, in the moments when the dramatic situation did catch his imagination, the music and drama are all that one expects from the mature Mozart.
La Clemenza di Tito was composed in Mozart's final year; he died in the winter of 1791. The opera was not successful at its premiere after the coronation banquet. In fact, it was regarded by many as a complete flop. The opera grew in popularity after 1800, however, and was performed repeatedly in Prague in the early nineteenth century. La Clemenza is perhaps somewhat infamous as the opera whose commission interrupted Mozart's work on The Magic Flute and the Requiem.