The MASS IN B-FLAT MAJOR, "THERESIENMESSE," HOB.XXII: 12, is one of six masses that Franz Joseph Haydn (1732-1809) wrote to celebrate the name-day of his patron�s wife, Princess Maria Josepha Hermenegilde of Esterh�zy. Named after the Empress Marie Therese, the mass may have been heard for the first time at Eisenstadt on the occasion of the princess� birthday, September 8, 1799. It is admired for its contrapuntal refinement and elaborate vocal solos. Instrumentation: 0.0.2.1(opt): 0.2.0.0: Timp: Org: Str (2.2.2.1.1 in set): Solo SATB, Mx Chor.