Ravel completed two operas, and worked on three others. The unrealised three were "Olympia", "La cloche engloutie" and "Jeanne d'Arc". "Olympia" was to be based on Hoffmann's "The Sandman"; he made sketches for it in 1898–99, but did not progress far. "La cloche engloutie" after Hauptmann's "The Sunken Bell" occupied him intermittently from 1906 to 1912, Ravel destroyed the sketches for both these works, except for a ""Symphonie horlogère"" which he incorporated into the opening of "L'heure espagnole". The third unrealised project was an operatic version of Joseph Delteil's 1925 novel about Joan of Arc. It was to be a large-scale, full-length work for the Paris Opéra, but Ravel's final illness prevented him from writing it.