Simplify the following text for a Grade 5 native English-speaking person.
Original: Now he was able to mount his most famous work , Ossian ou Les bardes , with great success at the OpÃ ra and with the Emperor , who accorded the composer of his favorite opera the cross of the LÃ gion d'honneur .
Simplified: He was then able to have his most famous work performed at the OpÃ ra . It was called Ossian ou Les bardes .