The Missa in honorem Beatissimae Virginis Mariae (Hob. XXII:4) in E♭ major was written by Joseph Haydn for performance in Esterhaza in 1770. It was part of Haydn's duties to compose musical masses. It contains smaller organ obliggato, in contrast to the Kleine Organ Mass, or Missa brevis Sancti Joannis de Deo. It is known as the Gross Orgelsolo Mass in German speaking lands. [1]