The Second World War was the first war in which air power was to play a decisive role. The rear, which historically had always been protected by the front, would be wide open to the enemy's air and deep penetration forces on the ground unless these could be counted on equal terms. This threat to Royal Air Force stations was initially countered by the formation of Defence Squadrons. No. 757 Defence Squadron was formed at RAF Nutts Corner in Northern Ireland in late 1940 and on 19 December 1941 was re-numbered to No. 2757 Squadron. However, the scale of the German assault in Crete and the speed at which the airfield had fallen acted as a catalyst on British Defence planning and highlighted the need for the coordinated defence of airfields.