He re-established himself in Paris during the 1870s, with revivals of some of his earlier favourites and a series of new works, and undertook a popular U. As he was by then the permanent cantor of the local synagogue, Isaac could afford to pay for his son to take lessons from the well-known cellist Bernhard Breuer.
In 1858, Offenbach produced his first full-length operetta, Orphée aux enfers ("Orpheus in the Underworld"), which was exceptionally well received and has remained one of his most played works.
During the 1860s, he produced at least 18 full-length operettas, as well as more one-act pieces.
Offenbach became associated with the Second French Empire of Napoleon III; the emperor and his court were genially satirised in many of Offenbach's operettas.
Napoleon III personally granted him French citizenship and the Légion d'Honneur.
He made a favourable impression on the composer and conductor Fromental Halévy, who gave him lessons in composition and orchestration and wrote to Isaac Offenbach in Cologne that the young man was going to be a great composer.