The "Marines' Hymn" is the official hymn of the Unite States Marine Corps. It is the oldest official song in the United States military. The song has an obscure origin—the words date from the 19th century, but no one knows the author. The music is from the Gendarmes' Duet from the opera Geneviève de Brabant by Jacques Offenbach, which debuted in Paris in 1859. The Marine Corps secured a copyright on the song on August 19, 1919, but it is now in the public domain.