The First World War brought with it the first attack on Britain from the skies above. Defence historically related to the coastline (not airspace), and with the Royal Flying Corps operating mainly overseas, Britain had few aircraft and was not well prepared to counter an aerial threat. The first attacks were from Zeppelins, which undertook surprise attacks in 1915 and 1916. Counteractive measures were brought in – the dimming of street lights, better utilisation of guns, searchlights and observers, the recall of air squadrons and the development of incendiary ammunition. By 1917, Gotha bomber attacks had commenced. This required the development of new aerial combat tactics, wireless communications, sophisticated observation practises, increased reporting on the enemy, anti-aircraft fire and barrage balloons. These all helped the efficacy of British fighter planes and reduced the accuracy of attacks and the aerial threat to Britain reduced during 1918.