Aviation became the definitive weapon of post-WW1 conflict and significantly influenced the course of the Spanish Civil-War. Bombing was the perfect tool to disrupt the economy of war and the Bombing of Barcelona was the first large-scale and systematic aerial bombardment of any city. Seeing as Barcelona was easy to locate due to its characteristic seafront, authorities decided against continuing a passive defence of the sea and air, instead focussing on protecting their citizens through active defences, designed to neutralise enemy bombardments. For the locating of enemy planes, observation and listening centres were used. However, its lighting projectors, reflectors and acoustic locator apparatus (early form of radar) were not very precise. As for the neutralisation of enemy attacks, anti-aircraft guns and fighter planes were used.