Nevertheless, it was <answer>radar</answer> that proved to be critical weapon in the night battles over Britain from this point onward. Dowding had introduced the concept of airborne <answer>radar</answer> and encouraged its usage. Eventually it would become a success. On the night of 22/23 July 1940, Flying Officer Cyril Ashfield (pilot), Pilot Officer Geoffrey Morris (Observer) and Flight Sergeant Reginald Leyland (Air Intercept <answer>radar</answer> operator) of the Fighter Interception Unit became the first pilot and crew to intercept and destroy an enemy aircraft using onboard <answer>radar</answer> to guide them to a visual interception, when their AI night fighter brought down a Do 17 off Sussex. On 19 November 1940 the famous RAF night fighter ace John Cunningham shot down a Ju 88 bomber using airborne <answer>radar</answer>, just as Dowding had predicted.
What was critical in the night battles over Britain?
radar