Frederick wrote many Symphonies.
Frederick's Symphony in D.
Frederick's Concerto for flute.
Frederick II of Prussia was a talented musician, played the flute on a professional level, and he dabbled in composition, especially in his younger years. Music, for Frederick, was a pleasurable experience, a diversion from the cares of the day. In fact, much that was written at his court has pretty much faded for that reason; it is not all that memorable. Though the great Bach was a fixture of Frederick's court for a number of years, most of the corpus of his writing lends itself from the Hamburg years, not from Berlin and Potsdam. In Hamburg, the free city allotted a composer greater freedom of "thought" then a royal court.