Iphigénie en Aulide (Iphigeneia in Aulis) is an opera in three acts by Christoph Willibald Gluck, the first work he wrote for the Paris stage. The libretto was written by François-Louis Gand Le Bland Du Roullet and was based on Jean Racine's tragedy Iphigénie, itself based on the play Iphigenia in Aulis by Euripides. It was premiered on 19 April 1774 by the Paris Opéra in the second Salle du Palais-Royal and revived in a slightly revised version the following year. A German version was made in 1847 by Richard Wagner, with significant alterations.