In 1944 Berlin was probably the most defended city in the world. The Luftwaffe had kept what reserves it had for planes to defend Berlin. On March 6th, 1944, The USAAF were involved in the massive air raid on Berlin, 69 B17s were lost - but the Luftwaffe lost 160 planes. Whereas the US 8th Air Force could recover from these aircraft losses, the German Luftwaffe could not. By the end of the war, the 8th Air Force and the Royal Air Force had destroyed 70% of Berlin.