Franz Joseph Haydn wrote a concerto for trumpet that could never have been played before 1796.
That was the year that his friend, Anton Weidinger developed a new kind of trumpet: a trumpet with keys. Before this time, trumpets had no keys or valves whatsoever, and were very limited in the notes that could be smoothly strung together.
Weideinger and Haydn changed all that. Can you imagine the astonishment of the audience at the premiere when Anton Weidinger himself as soloist produced spectacular music, the likes of which had never been heard before?
Over the years the keyed trumpet has been replaced by the more versatile valved trumpet, but that concerto by Franz Joseph Haydn is still as spectacular as it was that first night in Vienna.