In Germany the growing threat from RAF Bomber Command was being addressed. More and more four engined heavy bombers were becoming operational and the head of Bommber Command, Air Marshall Harris was determined to prove that they were a war winning weapon by themselves. The RAF had achieved devastating results at Lubeck, a raid which had shocked the Nazi High Command. Then had come two ‘thousand bomber raids’ beginning with the raid on Cologne.
A better co-ordinated fighter defence system, the ‘Y’ system was now brought into operation. RAF Fighter Command had pioneered the close integration of radar early warning and fighter control during the Battle of Britain. This was just the latest stage in a competing arms race between bombers and air defence technologies on both sides of the war.
Heinz Knocke was a Luftwaffe pilot assisting with the development of the new scheme. On the 22nd June 1942 he noted his impressions in his diary:
The introduction of the new “ Y ” system results in vastly improved long-distance radio communications between aircraft in flight and the ground. Operationally speaking, it will now be possible for our fighters to be located and directed by ground control at all times.
The control-room itself is in an enormous bomb-proof concrete shelter. In the centre stands a huge map of Holland on plate glass about thirty feet square. On the far side of this giant map there is a raised platform, with Air Force girls sitting at a battery of headphones and microphones. The girls receive reports of approaching enemy aircraft from radar stations along the coast, and project lights which are moved across the map to maintain a continuous plot of their positions.
Other girls locate our own lighters by means of the “ Y ” system, and plot their positions on the map also.
In front of this map there is another raised platform, equipped with a complicated arrangement of microphones and switches. From here every single fighter formation can be directed by ground-control officers individually by ultra-short-wave radio telephone. A glance at the map is all that is required to obtain a complete picture of the changing situation at any given moment.
The entire scene is presided over by the Division Commander sitting at the control desk with his Senior General Staff Officer and Chief Intelligence Officer.
Approximately 1,000 officers, N.C.O.s, soldiers, technicians, meteorologists, administrative officials, and a large number of very pretty girls keep this fighter control headquarters functioning as a directing brain by day and night.