Mozart's Piano Sonata No. 15 in D major, K. 576, was composed in 1789 as part of a set of six sonatas for Princess Friederike of Prussia. It is often nicknamed "The Hunt" or "The Trumpet Sonata", for the hornlike opening. This was the last piano sonata that Mozart wrote.
In a letter to Michael von Puchberg, Mozart wrote "meanwhile I am working on six easy piano sonatas for Princess Friederike and six quartets for the King". While we don't know for certain that her was referring to this sonata, K. 576 is demanding to play and often considered one of Mozart's hardest sonatas due to its technically difficult counterpoint passages.