French opera began around the 1660’s. Louis XIV loved ballet and ALL French opera had to have ballet incorporated. In fact French opera was almost as much ballet as music. Even into the late 1800’s an opera that was to play in Paris had to have some ballet in it. Verdi and Wagner both had to find someplace in one of their finished opera’s to put a piece of ballet before it played in Paris. Wagner couldn’t find a good spot so he stuck it to the beginning of the opera to get it over with. The French were not happy since someone arriving late would miss the ballet portion so the opera was a flop.
(The Great Courses – How to Listen to and Understand Opera)