Wolfgang Amadeus Mozart's final Masterpiece was commissioned in mid 1791 by the Austrian count Franz Von Walsegg, as a Tribute to the passing of his young wife Anna. Mozart began his final composition in Prague, suffering from an undetermined illness, which would eventually take his life and rob him of the chance to see the completion of his Magnum Opus. After Mozart's death, his understudy 'Franz Xaver Süssmayr', at the behest of Mozart's wife, completed the missing parts of the Requiem. Requiem Mass was first performed on January 2, 1793, in a private concert for the benefit of Mozart's grieving wife, Constanze Mozart.