Filling in for Denmark

From 1809 to 1981 Denmark was at war with Huéscar, but people apparently forgot about it, and not a single bullet was fired.

Written by Icelandic composer Jón Leifs in 1964, the piece called Hekla, Op 52, requires four sets of rocks hit with hammers, steel plates, anvils, sirens, cannons and metal chains to play.