On the same date the Combined Bomber Offensive began around the clock bombing of German-occupied Europe—the defence of these regions became known as the Defence of the Reich. The purpose of the offensive was to destroy the "Luftwaffe" and its supporting facilities in Europe through aerial bombardment and the destruction of German fighter defences in combat. Air superiority was to be achieved before Operation Overlord. The US Eighth Air Force operations created a crisis in July and August 1943. In March 1943, an immediate rise in losses had already been noted. A report from "Luftflotte" 3 recognised the size and defensive power of American bombers required a timely interception by massed formations for any chance of success. In July alone, western fighter forces lost 335 single-engine aircraft to all causes—18.1 percent of the available strength reported on 1 July. There was also a noticeable decline in the quality of pilot training.