Changing Tactics: The switch to night-time bombing
The entire battle was not over. It would run on for several more months but the objective of the Luftwaffe to destroy the RAF as a precursor to invasion had failed utterly. By mid-September Göring realised he had no effective way of protecting his bomber force using fighters as escorts. The losses had been devastating and crew morale in all branches was low. The Ju87 Stukas were being withdrawn to be followed shortly by the Messerschmitt Bf110s whose vulnerability to modern fighters had been fully demonstrated by Fighter Command. The Bf109s of the Jagdgeschwader could mount no effective attack alone and were soon to be harried over France and Belgium by RAF fighter sweeps.
The planned date for invasion was fast approaching, but the weather was now deteriorating and the tides in the channel made the chances of an unopposed landing most unlikely. Neverthheless, the Luftwaffe had to continue. With the exception of intruder raids and mine laying operations, most of the bomber force had been used in escorted daylight operations but from September 7th when they had been directed at London rather than the airfields there was now a noticeable move towards night-time operations where darkness could cover the bomber's approach. For night navigation Luftwaffe bombers were equiipped with Knickbein or X-gerät, two sophisticated radio navigation systems. Meanwhile daylight Jabo raids against coastal towns and cities were intensified by the Jagdgeschawder keeping Fighter Command fully occupied.
The change in tactics presented Fighter Command with a number of problems. The depleted squadrons were exhausted and neither Hurricanes or Spitfires were equipped or trained for a night-fighter role. Everything hinged on the development of effective, light and compact air-interception equipment. The Fighter Interception Unit (FIU) had been established in April 1940 at Tangmere to explore the night-fighter role using air interception radar but this was for evaluation purposes rather than an operational role. Despite this Blenheim 1Fs of the FIU destroyed a number of enemy aircraft.
The two Defiant I squadrons operating in 11 and 12 Groups during the summer of 1940 had suffered appalling losses and had been withdrawn from day fighter operations. 264 Sqn had been given a night-fighter role as early as April 1940 but it was used as a day fighter over Dunkirk in late May and June. It returned to the night-fighter role, but without air interception radar which was too heavy and bulky for the aircraft to use. 141 Sqn retrained in night-fighter operations from September 1940 before being equipped with Beaufighter 1Fs in August 1941. Both squadrons achieved moderate success in night operations despite the lack of AI equipment, relying instead on the crew's eyesight and the guidence from searchlights on the ground below. It was not until the development of the A.I MkIV that the Defiant II was fully equipped for the job in in late 1941. Six Blenheim squadrons also took on the night-fighter role among them 604 Sqn at Middle Wallop in 10 Group. Over the winter of 1940-1941 they became the top scoring squadon and were each slowly re-equipped with the Beaufighter 1F but this, the first purpose-built night fighter, was beset with technical problems. Dowding was called to the Air Ministry and despite his objections was overruled and three Hurricane squadrons were redeployed as night fighters, again without air interception radar. It is therefore not surprising that the results were disappointing.
Night operations against British cities were increasing, Luftwaffe losses were falling and the blame for this was directed at Fighter Command, and Dowding in particular. This was a battle Dowding had planned from 1937. A battle he had equipped and commanded from June 1939. On 17th October after the battle was comprehensively won he was summoned to a meeting at the Air Ministry to discuss day fighter tactics. His opponents to his use of fighters and the Dowding system were all at the meeting and his method of combatting the Luftwaffe was now on trial. The advocates of the 'Big Wing' won the day.
This, together with the insufficient successes of the night-fighters at a time when cities were burning night after night, was the end for Dowding who was informed on November 13th that his services were no longer required. He relinquished his Command on November 24th and was dispatched on a buying mission to the United States. Air Vice Marshall Park, 11 Group's Commander, was also dismissed to a Training Command. His place was taken by Trafford Leigh Mallory, Commander of 12 Group.
It was a very bright spark of light in a very dark world.