Offenbach's early operettas were small-scale one-act works, since the law in France limited musical theatre works (other than grand opera) to one-act pieces with no more than three singers and, perhaps, some mute characters.
Offenbach's early operettas were compact, one-act productions, due to French legislation restricting musical theatre pieces (excluding grand opera) to single-act works with a limited number of singers and possibly mute characters.