The Rocket War of Vrontados

The Rocket War of Vrondados is an old custom that began at the time of the Turkish occupation and it still happens every year at Easter. In the beginning the residents of the parishes of Panagia Erithiani and Saint Mark's, which are facing each other, made small cannons, to fire at each other. But through time the canons became rockets and fireworks made from nitre, sulphur and gunpowder.

http://www.lesvos-ecotourism.com/greekislands_chios_festivals.html -via Cynical-C