http://en.wikipedia.org/wiki/1812_Overture
This actually a classical music piece meant to have cannon fired. Old type cannon since it was a commemoration of Napoleon's defeat.
Toward the end of it an assistant conductor will be working with the cannoneers and we'll fire in time with the music. Some cannon will go once and some twice. It leads to hustle if twice since it is under the time limit of modern standards for black powder cannon firing.
After the piece is over the cannon will fire one or two rounds. If two the first is a rolling volley down the line and the second is all at once.
This used to be most impressive years ago when people would come up from New Mexico and more local people took part but competing events and politics have reduced the number. Still it is fun for all - except dogs. Unless they are gun dogs leave them home.
Steve