The Supermarine Spitfire remains one of the most iconic and mass-produced aircraft ever developed. It is regarded as the only British fighter able to meet the German Messerschmitt Bf109E on equal terms during the Battle of Britain, with outcomes of engagements often depending more on the quality of the pilots than the aircraft. While the United States produced far more military aircraft than any other country during WWII, more Spitfires were produced by Britain than any other WWII US military fighter or bomber.