Who defended Britain against the Nazi Luftwaffe?

Winston Churchill called them "The Few". They were the Royal Air Force Fighter Command. Because of their network of radar stations, Fighter Command was able to detect where the Luftwaffe bombers were coming from and send their meager resources to meet them, flying several sorties a day. The second technological advantage was the inverted V-12 Merlin engine in their Hurricane and Spitfire fighter planes which matched the capabilities of the advanced German fighter engines.