Mozart showed amazing talent from early in childhood. Already competent on the keyboard and violin, he started composing from the age of five and performed before European royalty. At 17, he was enlisted as a court musician in Salzburg, but grew restless of this and decided to travel in search of a better position, always composing abundantly.
The Requièm Mass in D minor was composed in Vienna in 1791 and was left unfinished when Mozart died on December 5th 1791. A completion dated 1792 by Franz Xaver Süssmayr was delivered to Count Franz von Walsegg, who had anonymously commissioned the piece for a requiem mass to commemorate the February 14th anniversary of his wife's death.
A facsimile sheet of music from the Dies Irae movement of the "Requiem Mass in D Minor" (K. 626) in Mozart's own handwriting. It is located at the Mozarthaus in Vienna.