The origins of this tradition could go back to a dispute with the nearby village of Miranda de Ebro over the ownership of some local crags. First there is a mass, and then this peaceful battle between two sides begins. The participants tirelessly despatch litres and litres of wine over their adversaries. It is an impressive spectacle that lasts until lunchtime. Afterwards, the people head back to Haro and gather in Plaza de la Paz Square.