Operetta developed in the second half of the 19th century from the French opera-comique and the more lighthearted German Singspiel.
As the century progressed, the serious concerns of mainstream opera were sustained and intensified, leaving a gap between opera-comique and vaudeville that necessitated a new type of stage work.
Cambridge Scholars Publishing Operetta. a sourcebook, volume i, hardback/robert ignatius letellier
