Analysis from Wikipedia.
The chess game played in 1858 at an opera house in Paris between the American chess master Paul Morphy and two strong amateurs, the German noble Duke Karl of Brunswick and the French aristocrat Count Isouard, is among the most famous chess games. Duke Karl and Count Isouard consulted together, playing as partners against Morphy. The game is often used by chess instructors to teach the importance of rapid development of one's pieces, the value of sacrifices in mating combinations, and other chess concepts. The game is sometimes called "The Opera Game".
On several occasions, the Duke invited Morphy to the Italian Opera House in Paris, Salle Le Peletier, where the former kept a private box which was, according to Morphy's associate Frederick Edge, so close to the stage that one "might kiss the prima donna without any trouble", and which always contained a chess set, the Duke being a keen player as well as an opera lover.
Morphy was extremely fond of music and opera and was eager to see Norma, which played on his first visit. Unfortunately, his host had seen Norma countless times, and Morphy found himself forced to play chess, even seated with his back to the stage.
As the game progressed, the two allies conferred loudly enough with each other, debating their moves against the American genius, that it attracted the attention of the opera performers. Madame Penco, who had the role of the Druidic priestess inNorma, kept looking into the Duke's box, to see what all the fuss was about, even as she was performing the opera. Then the performers who were the Druids, marched about, "chanting fire and bloodshed against the Roman host, who, they appeared to think, were in the Duke's box", Edge recounted.
It is doubtful if the distracted opera singers had a good enough view of what was going on. Comically, Morphy created this brilliant game while spending his time trying to overcome his blocked view of the opera, while the performers tried to catch glimpses of what was going on in the Duke's box.
Norma was performed at the Italiens de Paris on 21 October 1858, with Rosina Penco in the title role, L. Graziani as Pollione and Cambardi as Adalgise. Some commentators would rather have the chess game taking place with The Barber of Seville,La Cenerentola, or else The Marriage of Figaro on stage.