Wikipedia
Ba-ta-clan is a " chinoiserie musicale" (or operetta) in one act with music by Jacques Offenbach to an original French libretto by Ludovic Halévy. It was first performed at the Théâtre des Bouffes Parisiens, Paris, on 29 December 1855. The operetta uses set numbers and spoken dialogue and runs for under an hour.
Ba-ta-clan was Offenbach's first big success, and opened his new winter theatre, the Salle Choiseul. The witty piece satirised everything from contemporary politics to grand opera conventions. It was frequently revived in Paris, London and New York for decades, and Offenbach eventually expanded it as a full-length piece with a cast of eleven. Offenbach's early operettas were small-scale one-act works, since the law in France limited the licence for musical theatre works (other than most operas) to one-act pieces with no more than three singers and, perhaps, some mute characters. In 1858, this law was changed, and Offenbach was able to offer full-length works, beginning with Orpheus in the Underworld.
In 1864, a music-hall called Bataclan opened in Paris, named after the operetta, and is still functioning today.