was summoned on 17 October, to explain the poor state of the night defences and the supposed (but ultimately successful) "failure" of his daytime strategy. The Minister of Aircraft Production, Lord Beaverbrook and Churchill distanced themselves. The failure to prepare adequate night air defences was undeniable but it was not the responsibility of the AOC Fighter Command to dictate the disposal of resources. The general neglect of the RAF until the late spurt in 1938, left few resources for night air defence and the Government, through the Air Ministry and other civil and military institutions was responsible for policy. Before the war, the Chamberlain government stated that night defence from air attack should not take up much of the national effort. Technology German night navigation devices Because of the inaccuracy of celestial navigation for night navigation and target finding in a fast-moving aircraft, the Luftwaffe developed radio navigation devices and relied on three systems: Knickebein (Crooked leg), X-Gerät (X-Device), and Y-Gerät (Y-Device). This led the British to develop countermeasures, which became known as the Battle of the Beams. Bomber crews already had some experience with the Lorenz beam, a commercial blind-landing aid for night or bad weather landings. The Germans adapted the short-range Lorenz system into Knickebein, a 30–33 MHz system, which used two Lorenz beams with much stronger signals. Two aerials at ground stations were rotated so that their beams converged over the target. The German bombers would fly along either beam until they picked up the signal from the other beam. When a continuous sound was heard from the second beam the crew knew they were above the target and dropped their bombs. Knickebein was in general use but the X-Gerät (X apparatus) was reserved for specially trained pathfinder crews. X-Gerät receivers were mounted in He 111s, with a radio mast on the fuselage. The system worked on 66–77 MHz, a higher frequency than Knickebein. Ground transmitters sent pulses at a rate of 180 per minute. X-Gerät received and analysed the pulses, giving the pilot visual and aural directions. Three cross-beams intersected the beam along which the He 111 was flying. The first cross-beam alerted the bomb-aimer, who activated a bombing clock when the second cross-beam was reached. When the third cross-beam was reached the bomb aimer activated a third trigger, which stopped the first hand of the clock, with the second hand continuing. When the second hand