Douglas Harper's Etymology Dictionary
Marsellaise
French national republican song, 1826, from fem. of adjective Marseillais "of Marseilles." The tune originally was "War Song for the Rhine Army," composed (for the Strasbourg volunteers) by royalist officer Capt. Claude Joseph Rouget de Lisle (1760-1836); current name is because it was sung enthusiastically by soldiers from Marseilles advancing on the Tuileries, Aug. 10, 1792.