185:
know that they had to veer to the right to fly down the centreline. If the crew was on the right side of the centerline, they would hear a series of long tones followed by short pauses, meaning the aircraft was on the "dash" side of the antenna. Hearing the "dashes", they would know that they had to veer to the left to fly down the centreline. In the centre, the radio would receive both signals, where the dots filled in the gaps in the dashes and produced a continual signal, the so-called "equisignal". Flying in the known direction of the runway and keeping the equisignal on the radio, Lorenz-equipped crews could guide an aircraft down a straight line with a relatively high degree of accuracy, so much so that pilots could then find the runway
801:) that received the signal from the beam and immediately re-transmitted it to the ground station. The ground station listened for the return signal and compared the phase of its modulation to the transmitted signal, which accurately determined the transit time of the signal, and hence the distance to the aircraft. Coupled with the direction of the beam (adjusted for a maximum return signal), the bomber's position could be established with considerable accuracy. The bombers did not have to track the beam, instead the ground controllers could calculate it and then give radio instructions to the pilot to correct the flight path.
260:
836:. All Jones had to do was arrange for the return signal to be received from the aircraft and then sent to Alexandra Palace for re-transmission. The combination of the two signals modified the phase shift, and thus the apparent transit delay. Initially, the signal was re-transmitted at low power, not powerful enough for the Germans to realise what was happening, but enough to spoil the accuracy of the system. Over subsequent nights, the transmitter power was gradually increased.
292:
465:
814:
128:
119:. Having guessed the nature of this system from a passing mention, the British had already deployed countermeasures that rendered the system useless almost as soon as it was used. The Germans eventually abandoned the entire concept of radio navigation over the UK, concluding the British would continue to successfully jam it.
450:
their dots at the same time as the German transmitters, making it impossible to tell which signal was which. In this case the navigators would receive the equisignal over a wide area, and navigation along the bomb line became impossible, with the aircraft drifting into the "dash area" and no way to correct for it.
288:
aerials could be rotated to make the beams from two transmitters cross over the target. The bombers would fly into the beam of one and ride it until they started hearing the tones from the other (on a second receiver). When the steady "on course" sound was heard from the second beam, they dropped their bombs.
713:
equipment was recovered. On examination, it was learned that a new instrument was being used that automatically decoded the dots and dashes and moved a pointer on a display in the cockpit in front of the pilot. This device was fitted with a very sharp filter which was sensitive only at 2,000 Hz,
453:
Thus the beam was seemingly "bent" away from the target. Eventually, the beams could be inclined by a controlled amount which enabled the
British to fool the Germans into dropping their bombs where they wanted them. A side effect was that as the German crews had been trained to navigate solely by the
854:
The
Luftwaffe, finally realising that the British had been deploying countermeasures from the very first day that the system was used operationally, completely lost faith in electronic navigation aids as the British had predicted, and did not deploy any further system against Great Britain, although
728:
beam — much earlier than the expected 5 kilometres (3.1 mi). Since the final stages of the release were automatic, the clock would reverse prematurely and drop the bombs kilometres short of the target. Setting up this false beam proved very difficult as the
Germans, learning from their mistakes
693:
in an attempt to disrupt the
Coventry raid but proved to be a failure. Although Jones had correctly guessed the beam layout (and acknowledges it was only a guess), the modulation frequency had been measured incorrectly as 1,500 Hz, but was in fact 2,000 Hz. At the time it was believed that
449:
The low-power "dot signal" was initially transmitted essentially at random, so German navigators would hear two dots. This meant there were many equisignal areas, and no easy way to distinguish them except by comparing them with a known location. The
British transmitters were later modified to send
400:
The crew were not told specifics, and were simply ordered to search for radio signals around 30 MHz having Lorenz characteristics and, if they found any, to determine their bearing. The flight took off and eventually flew into the beam from Kleve, on 31.5 MHz. It subsequently located the
287:
The beam from a single transmitter would guide the bombers towards the target, but could not tell them when they were over it. To add this ranging feature, a second transmitter similar to the first was set up so its beam crossed the guidance beam at the point where the bombs should be dropped. The
184:
An aircraft approaching the airport would tune one of their radios to the Lorenz frequency. If the crew was on the left side of the centreline, they would hear a series of short tones followed by long pauses, meaning the aircraft was on the "dot" side of the antenna. Hearing the "dots", they would
751:
As the
British slowly gained the upper hand in the Battle of the Beams, they started considering what the next German system would entail. Since Germany's current approaches had been rendered useless, an entirely new system would have to be developed. Jones believed that if they could defeat this
445:
sets transmitted interference. Later, local radio transmitters broadcast an extra "dot signal" at low power on nights where raids were expected. The German practice of turning on the beams long before the bombers reached the target area aided the
British efforts. Avro Ansons fitted with receivers
234:
and giving the navigator room to do his calculations in an illuminated workspace. This system was put to use as soon as the war began and was initially regarded as successful. In reality, the early bombing effort was a complete failure, with the majority of bombs landing miles from their intended
271:
For bombing use, the modifications to Lorenz were fairly minor. Much larger antennas were needed to provide the required accuracy. This was achieved by using aerials with many more elements, but it retained the simple switching of two of the reflector elements to alter the beam directions very
180:
on either side set slightly back. A switch rapidly alternated the opened midpoint connection of each reflector in turn, sending the beam slightly to the left and then slightly to the right of the centreline of the runway. The beams widened as they spread from the antennas, so there was an area
846:
s use went on, the aircrew accused the ground station of sending bad signals and the ground station alleged the aircraft had loose connections. The whole scheme appealed to Jones as he was a natural practical joker, and remarked that he was able to play one of the largest practical jokes with
804:
Jones later learned that his guess on the operating principle based on the name Wotan was entirely by luck. Later documents showed that the original X-Gerät was known as Wotan I, and the Y-Gerät as Wotan II. Had he known the name was also associated with X-Gerät it was unlikely he would have
243:
systems. The
Luftwaffe concentrated on developing a bombing direction system based on the Lorenz concept through the 1930s, as it made night navigation relatively easy by simply listening for signals on a radio set, and the necessary radios were already being installed on many aircraft.
847:
virtually any national resource that he required. The gradually increasing power conditioned the
Germans such they did not realise that the system was being interfered with, but believed that it suffered several inherent defects. Eventually, as the power was increased enough, the whole
331:
Knickebein was used in the early stages of the German night-bombing offensive and proved to be fairly effective, but the tactics for using the system in a widespread bombing effort were not yet developed, so much of the early German night bombing offensive was limited to area bombing.
783:, a one-eyed god, and might refer to a single-beam navigation system. Jones agreed, and knew that a system with one beam would have to include a distance-measurement system. He concluded that it might work on the basis described by the anti-Nazi German mathematician and physicist
397:. The flight was nearly cancelled when Eckersley withdrew his assertion that the beams would bend around the Earth. Jones saved the flight by pointing out that Churchill himself had ordered it, and he would make sure that the Prime Minister would learn who cancelled it.
212:, but this threat could be essentially eliminated by flying at night. A bomber, painted black, could be spotted only at very short ranges. As the bomber's altitude and speed increased, the threat from ground-based defences was greatly reduced. Planners believed that "
112:, the British responded by sending their own Morse code signals so that the aircraft crew believed they were always properly centred in the beam while they flew wildly off course. The Germans became convinced the British had somehow learned to bend radio signals.
500:
from a similarly sized antenna; the equi-signal area was only about 100 yards (91 m) wide at a distance of 200 miles (320 km) from the antenna. The beams were so narrow that bombers could not find them without help, so a low-power wide-beam version of
714:
and not to the early
British 1,500 Hz counter-signals. While the jammers were modified accordingly, this came too late for the raid on Coventry on 14 November; but the modified jammers were able to successfully disrupt a raid on Birmingham on 19 November.
352:
analysed a downed German bomber's Lorenz system and observed it was far more sensitive than required for a mere landing aid. Secretly recorded transcripts from German prisoner of war pilots indicated this may have been a bomb aiming aid.
327:
near the border with France and Switzerland in south-western Germany. Following the fall of France in June 1940, additional transmitters were installed on the French coast. Stations were also constructed in Norway and the Netherlands.
564:
did not require the same precision and was approximately 30 kilometres (18.6 mi) before the release point. The beams' width added a small error to the intersection coordinates, on the order of tens to hundreds of meters.
380:
Eckersley's assertion was eventually demonstrated after Churchill ordered a flight to try to detect the beams. The RAF lacked equipment capable of detecting 30–33 MHz Lorenz signals, so they purchased an American
368:
When Jones mentioned the possibility of bombing beams to Churchill, he ordered further investigation. The British codenamed the system Headache. Many in the Air Ministry did not believe that the system was in use.
413:
engine. It was subsequently realised that the argument over whether the beams would bend around the Earth was entirely academic, as the transmitters were more or less in line-of-sight to high altitude bombers.
238:
The Luftwaffe did not take such a fatalistic view of air warfare, and continued to research accurate night bombing against smaller targets. Not depending on celestial navigation, they invested their efforts in
480:
was, it was never intended to be used in the long-range role. Plendl had been working for some time to produce a much more accurate version of the same basic concept, which was eventually delivered as
401:
cross beam from Stollberg (its origin was unknown prior to this flight). The radio operator and navigator were able to plot the path of the beams and discovered that they intersected above the
2529:
272:
marginally. The beam angles were so dramatically reduced that it was only a few tens of yards wide over the target. It was the shape of the aerials that gave the system its code name,
927:
The information in this report was plentiful and seemingly far too useful to be true, and many considered it to be a German disinformation campaign. The Oslo Report's description of
604:
to release point distance, a bomber flying at constant speed arrived at the release point as the moving hand reached zero, when the bombs were automatically released.
85:'s midline. Radio operators in the aircraft listen for these signals and determine which of the two beams they are flying in. This is normally accomplished by sending
798:
417:
British sceptics started regarding the system as proof that the German pilots were not as good as their own, who they believed could do without such systems. The
2420:
584:
signal was received, one hand stopped and the other reversed, sweeping back towards zero. The stopped hand indicated an accurate measurement of travel time from
454:
beams, many crews failed to find either the true equisignal or Germany again. Some Luftwaffe bombers even landed at RAF bases, believing they were back at base.
666:
100 was used and British post-raid analysis showed that the vast majority of the bombs dropped were placed within 100 yards (91 m) of the mid-line of the
1605:
219:
The problem with night bombing is that the same limitations in visibility meant the bomb crew would have a difficult time finding their targets, especially a
108:" with great effect, in one case laying a strip of bombs down the centerline of a factory deep in England. Tipped off about the system's operation by pre-war
1631:
Site (in German) listing locations of radio beam transmitters as well as radar early-warning stations (interesting photos and extensive list of references)
181:
directly off the runway approach where the two signals overlapped. The switch was timed so it spent longer on the right side of the antenna than the left.
797:
used a single narrow beam pointed over the target, similar to earlier beam systems, transmitting a modulated radio signal. The system used a transponder (
2539:
767:. Jones had already concluded the Germans used code names that were too descriptive, so he asked a specialist in the German language and literature at
633:
100 aircraft would attack as a small group first, dropping flares which other aircraft would then see and bomb visually. This is the first use of the
2524:
1734:
885:
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this would not make any difference, as the tones were close enough that an operator would have a hard time distinguishing them in a noisy aircraft.
496:
but operated at a much higher frequency. Due to the nature of radio propagation, this allowed its two beams to be pointed much more accurately than
208:, which were beginning to have the capability to strike across Europe with useful bomb loads. These aircraft were slow and lumbering, easy prey for
614:(around 60 MHz) and thus required the use of new radio equipment. There was not enough equipment to fit all bombers, so the experimental unit
1754:
153:
in the development of commercial aviation, and in systems and methods that would improve safety and reliability. Considerable effort went into
373:, leading scientific adviser to the government, argued that any such system would not be able to follow the curvature of the Earth, although
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1981:
1976:
1971:
1966:
1961:
1956:
1951:
1946:
1941:
1936:
1931:
370:
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To support this mission, the RAF invested heavily in navigation training, equipping their aircraft with various devices, including an
2549:
1657:
576:, the radio operator heard a brief signal and set up his equipment. This consisted of a special stop-clock with two hands. When the
2554:
1913:
284:
receivers were disguised as a standard blind landing receiver system, consisting apparently of the EBL-1 and the EBL-2 receivers.
1908:
1082:
1056:
824:
The British were ready for this system even before it was used. By chance, the Germans had chosen the operating frequency of the
670:
beam, spread along it for a few hundred yards. This was the sort of accuracy that even daytime bombing could rarely achieve. The
135:
and its two lobes. The "equisignal" area in the centre grows narrower, and more accurate, as the aircraft approaches the runway.
1903:
157:
aids which allowed aircraft to approach an airport at night or in foul weather. The primary system developed for this was the
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1556:
1529:
1510:
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1016:
1162:
2514:
2229:
2191:
2002:
213:
918:; 'bent leg' is the literal translation. An English speaker would use the phrase 'crooked leg' rather than 'bent leg'.
81:
aid. The basic concept is to produce two directional radio signals that are aimed slightly to the left and right of a
425:
returned photographs of the RAF bombing raids, showing that they were rarely, if ever, anywhere near their targets.
2456:
580:
signal was received the clock automatically started and the two hands simultaneously swept up from zero. When the
115:
When the problem became widespread, the Germans introduced a new system that worked on different principles, the
540:
or distance the bombs would travel between release and impact, and picking a point at that range to target. The
2017:
1739:
2196:
1650:
1814:
1666:
1635:
349:
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began to become paramount in military aviation circles. This was due to the ever-increasing performance of
532:. They were carefully aimed to define a precise bomb release trajectory. First a bomb release point along
2519:
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system badly. It operated at 45 MHz, which happened to be the frequency of the powerful-but-dormant
756:
59:
2509:
1564:
17:
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target at night. Only the largest targets, cities, could be attacked with any probability of success.
2534:
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2430:
446:
would be flown around the country to find the beams' location to be reported to nearby broadcasters.
2398:
2393:
1689:
1643:
914:
787:, who while visiting Norway had provided a large amount of information in what is now known as the
308:
2481:
2222:
724:" which was set up to cross the 'Weser' guide beam at a mere 1 kilometre (0.6 mi) after the
833:
2461:
1744:
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with full support from other units dropping on their flares almost destroyed the city centre.
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2471:
2466:
2451:
2119:
1852:
1837:
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1772:
1571:
1006:
422:
345:
165:, which was in the process of being widely deployed on large civilian and military aircraft.
109:
74:
1630:
650:
was used effectively in a series of raids known to the Germans as Moonlight Sonata, against
2446:
2186:
2124:
2104:
2012:
784:
556:
10 kilometres (6.2 mi) before the release point, or 5 kilometres (3.1 mi) before
488:
used a series of beams to locate the target, each beam named after a river. The main beam,
358:
231:
227:
209:
67:
1607:
World War II: Western Europe: Graph to show the accuracy of night bombing of German cities
637:
concept that the RAF improved to great effect against the Germans some three years later.
96:
built huge versions of the antennas to provide much greater accuracy at long range, named
8:
2099:
2056:
1923:
1832:
1827:
1822:
510:
186:
177:
144:
78:
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beams on until as late as possible, making it much more difficult to arrange the "false
2544:
2410:
2215:
2064:
1842:
1793:
1500:
709:, Bridport. Although the aircraft sank during the recovery operation, the waterlogged
410:
277:
220:
140:
1086:
1060:
276:, which means "crooked leg", although the word is also the name of a magical raven in
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2041:
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890:
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201:
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The system was first tested on 20 December 1939 when a bomber from KGr 100 flown by
344:
system required time to implement. British intelligence at the Air Ministry, led by
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2342:
2327:
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2160:
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1885:
1880:
1875:
1870:
1865:
874:
817:
706:
634:
374:
240:
198:
47:
37:
168:
The Lorenz system worked by feeding a special three-element antenna system with a
2357:
2332:
2317:
2292:
2150:
2072:
2007:
1860:
1721:
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615:
402:
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fought back with a variety of their own increasingly effective means, involving
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2297:
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2134:
2129:
2114:
2051:
880:
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702:
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173:
51:
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receiver from a shop in Lisle Street, London. The receiver was fitted into an
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2425:
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2282:
2262:
1699:
1539:
1496:
864:
655:
386:
382:
312:
154:
1665:
987:
689:. Initial defences against the system were deployed in a similar fashion to
280:. For the required range, transmitted power was increased considerably. The
2252:
1764:
1729:
1670:
641:
437:
headache were codenamed "Aspirin", playing on the British codename for the
55:
2312:
1479:
931:
was accurate, however and the report was later realised to be "for real".
893:, the December 1941-launched successor to GEE for RAF night bomber raids.
788:
418:
323:
near the Dutch border, almost the most westerly point in Germany, and at
158:
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105:
63:
42:
855:
by this time Hitler's attention was turning towards Eastern Europe.
1704:
1461:
A Radar History of World War II: Technical and Military Imperatives
651:
468:
Principle of the German night navigation and target-finding system
66:
moved their forces to the East in May 1941, in preparation for the
813:
780:
464:
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system quickly, the Germans might give up on the entire concept.
316:
205:
1551:. Pen & Sword Military Classics. Vol. 37. Leo Cooper.
82:
1505:. History of the Second World War. Vol. I. London: HMSO.
720:
was eventually defeated in another manner, by way of a "false
127:
629:
equipment to guide other aircraft to the target. To do this,
406:
320:
2207:
988:"knicken - Wörterbuch Deutsch-Englisch - WordReference.com"
505:
was set up at the same station to act as a guide. The main
2530:
Military history of the United Kingdom during World War II
1597:
Instruments of Darkness: The History of Electronic Warfare
1388:
1277:
1265:
1217:
755:
British monitors soon started receiving intelligence from
1436:
1145:
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548:
5 kilometres (3.1 mi) before the release point. The
1424:
1298:
1253:
1205:
644:
Hermann Schmidt flew over London at 7,000m (23,000 ft).
89:
signals into the two beams, to identify right and left.
1378:
1376:
1315:
1313:
877:, the early war RAF navigation system for night bombing
1522:
Phoenix Triumphant: The Rise and Rise of the Luftwaffe
1325:
1241:
1140:
1116:
1101:
1412:
1400:
1373:
1361:
1337:
1310:
1181:
1128:
46:) used a number of increasingly accurate systems of
1349:
968:
956:
705:crashed on 6 November 1940 on the English coast at
29:
Electronic warfare conflict in the Second World War
1610:. The National Archives: Catalogue ref: AIR 16/487
1229:
1037:
944:
1193:
886:List of World War II electronic warfare equipment
520:used a series of three very narrow single beams,
2496:
441:system, "Headache". Initially, modified medical
172:radio signal. The signal was fed to the centre
77:was developed during the 1930s, initially as a
851:system started to ring with all the feedback.
409:, at that time the only factory producing the
104:. These were used during the early stages of "
2223:
1651:
697:The mystery was eventually revealed after an
1502:British Intelligence in the Second World War
1057:"Dutch site mentioning date of construction"
492:, was similar in concept to the one used in
335:
2540:Science and technology during World War II
2230:
2216:
1658:
1644:
763:, which was also sometimes referred to as
377:of the Marconi company had said it could.
805:concluded the system used a single beam.
610:operated at a much higher frequency than
365:messages that mentioned 'bombing beams'.
197:During the early 1930s, the concept of a
54:. British scientific intelligence at the
2525:History of telecommunications in Germany
812:
463:
290:
258:
126:
1546:
1495:
1283:
1271:
1223:
1149:
1110:
1031:
1004:
625:100) was given the task of using their
509:antenna was set up just to the west of
14:
2497:
1519:
1477:
1235:
348:, became aware of the system when the
40:when bombers of the German Air Force (
2211:
1639:
1603:
1594:
1570:
1458:
1442:
1430:
1418:
1406:
1394:
1382:
1367:
1355:
1343:
1331:
1319:
1304:
1259:
1247:
1211:
1199:
1187:
1134:
1122:
1043:
974:
962:
950:
913:
808:
759:referring to a new device known as
685:proved more difficult to stop than
677:
536:was determined, by calculating the
307:transmitters was set up in 1939 on
24:
214:the bomber will always get through
25:
2566:
1624:
1083:"Dutch site mentioning locations"
662:. In the raid on Birmingham only
428:
247:
149:and the German aircraft industry
2550:World War II British electronics
2457:American Ambulance Great Britain
1580:. London: Book Club Associates.
393:and operated by a member of the
340:Efforts in Britain to block the
192:
189:except in the worst conditions.
2555:World War II German electronics
2192:RAF strategic bombing offensive
1289:
1155:
1075:
921:
176:, which had a slightly longer
1049:
998:
980:
904:
13:
1:
2237:
2197:United States Army Air Forces
1451:
1163:"Hallicrafters S-27 receiver"
1011:. Pen and Sword. p. 15.
252:
122:
60:jamming and deception signals
1667:Air Defence of Great Britain
1563:(Expanded from Episode 1 of
938:
361:intelligence from decrypted
350:Royal Aircraft Establishment
62:. The period ended when the
7:
2018:Women's Auxiliary Air Force
2003:Battle of Britain airfields
858:
568:As the bomber followed the
10:
2571:
2515:Electronic countermeasures
1565:The Secret War (TV series)
832:television transmitter at
775:. The specialist realised
744:
457:
68:attack on the Soviet Union
36:was a period early in the
2482:Women's Voluntary Service
2439:
2381:
2245:
2179:
2143:
2092:
2030:
1995:
1922:
1894:
1851:
1813:
1806:
1781:
1763:
1720:
1713:
1677:
421:proved this to be wrong;
50:for night bombing in the
1690:Royal Canadian Air Force
897:
336:The search for the beams
2421:Evacuation of civilians
1547:Johnson, Brian (2004).
1520:Hooton, Edward (1994).
1005:Johnson, Brian (2004).
303:The first of these new
2462:Auxiliary Fire Service
2426:Starfish (decoy) sites
1745:Trafford Leigh-Mallory
1595:Price, Alfred (1977).
915:[ˈknɪkəˌbaɪ̯n]
821:
600:distance equalled the
516:The "cross" signal in
473:
300:
268:
136:
2477:War Damage Commission
2472:National Fire Service
2467:Civil Defence Service
2452:Anti-Aircraft Command
1838:Anti-Aircraft Command
1524:. Arms & Armour.
1459:Brown, Louis (1999).
1397:, pp. 1972–1978.
992:www.wordreference.com
816:
733:, did not switch the
467:
433:Efforts to block the
423:aerial reconnaissance
315:near the border with
294:
262:
143:on 1 September 1939,
130:
110:military intelligence
75:beam radio navigation
2447:Air Raid Precautions
2187:Air Raid Precautions
2013:Royal Observer Corps
1445:, pp. 177, 179.
1295:Hooton 1999, p. 199.
357:had also been given
2406:Battle of the Beams
2156:Battle of the Beams
1833:RAF Coastal Command
1828:RAF Balloon Command
1823:RAF Fighter Command
1481:Battle of the Beams
1433:, pp. 175–177.
1307:, pp. 146–153.
1286:, pp. 558–559.
1274:, pp. 556–559.
1262:, pp. 135–136.
1226:, pp. 553–534.
1214:, pp. 127–129.
1034:, pp. 324–325.
371:Frederick Lindemann
34:Battle of the Beams
2520:Electronic warfare
1843:RAF Bomber Command
1794:Robert Watson-Watt
1705:Big Wing formation
822:
474:
405:engine factory at
301:
278:Germanic mythology
269:
202:strategic campaign
137:
2510:Battle of Britain
2490:
2489:
2205:
2204:
2042:Battle of Britain
2026:
2025:
1802:
1801:
1695:Strategic bombing
1587:978-0-241-89746-1
1558:978-1-84415-102-8
1531:978-1-85409-181-9
1512:978-0-11-630933-4
1470:978-1-4200-5066-0
1334:, pp. 44–45.
1250:, pp. 55–58.
1125:, pp. 84–85.
1018:978-1-4738-1965-8
572:beam and reached
552:beam intersected
544:beam intersected
472:for night bombing
355:Winston Churchill
178:reflector element
92:For bombing, the
16:(Redirected from
2562:
2535:Radio navigation
2505:Alexandra Palace
2399:Morrison shelter
2394:Anderson shelter
2389:Air raid shelter
2246:Towns and Cities
2232:
2225:
2218:
2209:
2208:
2171:German V weapons
1886:No. 14 Group RAF
1881:No. 13 Group RAF
1876:No. 12 Group RAF
1871:No. 11 Group RAF
1866:No. 10 Group RAF
1811:
1810:
1718:
1717:
1671:Second World War
1660:
1653:
1646:
1637:
1636:
1619:
1617:
1615:
1600:
1591:
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1516:
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1227:
1221:
1215:
1209:
1203:
1197:
1191:
1185:
1179:
1178:
1176:
1174:
1165:. Archived from
1159:
1153:
1147:
1138:
1132:
1126:
1120:
1114:
1108:
1099:
1098:
1096:
1094:
1085:. Archived from
1079:
1073:
1072:
1070:
1068:
1059:. Archived from
1053:
1047:
1041:
1035:
1029:
1023:
1022:
1002:
996:
995:
984:
978:
972:
966:
960:
954:
948:
932:
925:
919:
917:
912:
908:
845:
834:Alexandra Palace
818:Alexandra Palace
672:raid on Coventry
241:radio navigation
151:invested heavily
141:start of the war
48:radio navigation
38:Second World War
21:
2570:
2569:
2565:
2564:
2563:
2561:
2560:
2559:
2495:
2494:
2491:
2486:
2435:
2377:
2241:
2236:
2206:
2201:
2175:
2151:Barrage balloon
2139:
2088:
2035:
2033:
2022:
2008:Eagle Squadrons
1991:
1918:
1890:
1861:No. 9 Group RAF
1847:
1798:
1777:
1759:
1709:
1685:Royal Air Force
1673:
1664:
1627:
1622:
1613:
1611:
1588:
1577:Most Secret War
1559:
1532:
1513:
1486:
1484:
1471:
1454:
1449:
1441:
1437:
1429:
1425:
1417:
1413:
1405:
1401:
1393:
1389:
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1374:
1366:
1362:
1354:
1350:
1342:
1338:
1330:
1326:
1318:
1311:
1303:
1299:
1294:
1290:
1282:
1278:
1270:
1266:
1258:
1254:
1246:
1242:
1234:
1230:
1222:
1218:
1210:
1206:
1198:
1194:
1190:, pp. 131.
1186:
1182:
1172:
1170:
1169:on 23 July 2011
1161:
1160:
1156:
1148:
1141:
1133:
1129:
1121:
1117:
1109:
1102:
1092:
1090:
1089:on 24 July 2011
1081:
1080:
1076:
1066:
1064:
1063:on 24 July 2011
1055:
1054:
1050:
1042:
1038:
1030:
1026:
1019:
1003:
999:
986:
985:
981:
973:
969:
961:
957:
949:
945:
941:
936:
935:
926:
922:
910:
909:
905:
900:
861:
843:
820:in north London
811:
771:about the word
757:Enigma decrypts
749:
680:
484:(X-Apparatus).
462:
431:
375:T. S. Eckersley
338:
295:Later, smaller
257:
250:
195:
163:Johannes Plendl
161:, developed by
125:
30:
23:
22:
15:
12:
11:
5:
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2428:
2423:
2418:
2416:Baedeker Blitz
2413:
2408:
2403:
2402:
2401:
2396:
2385:
2383:
2382:Related topics
2379:
2378:
2376:
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2199:
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2181:
2180:Related topics
2177:
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2054:
2052:Baedeker raids
2049:
2044:
2038:
2036:
2031:
2028:
2027:
2024:
2023:
2021:
2020:
2015:
2010:
2005:
1999:
1997:
1993:
1992:
1990:
1989:
1987:12 AA Division
1984:
1982:11 AA Division
1979:
1977:10 AA Division
1974:
1969:
1964:
1959:
1954:
1949:
1944:
1939:
1934:
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1776:
1775:
1773:Frederick Pile
1769:
1767:
1761:
1760:
1758:
1757:
1755:Sholto Douglas
1752:
1747:
1742:
1737:
1735:Charles Portal
1732:
1726:
1724:
1715:
1711:
1710:
1708:
1707:
1702:
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1663:
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1655:
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1633:
1626:
1625:External links
1623:
1621:
1620:
1601:
1592:
1586:
1568:
1557:
1549:The Secret War
1544:
1530:
1517:
1511:
1497:Hinsley, F. H.
1493:
1478:Goebel, Greg.
1475:
1469:
1455:
1453:
1450:
1448:
1447:
1435:
1423:
1421:, p. 176.
1411:
1409:, p. 177.
1399:
1387:
1385:, p. 120.
1372:
1370:, p. 152.
1360:
1348:
1346:, p. 164.
1336:
1324:
1322:, p. 151.
1309:
1297:
1288:
1276:
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1252:
1240:
1228:
1216:
1204:
1192:
1180:
1154:
1152:, p. 553.
1139:
1137:, p. 127.
1127:
1115:
1113:, p. 324.
1100:
1074:
1048:
1036:
1024:
1017:
1008:The Secret War
997:
979:
977:, p. 109.
967:
965:, p. 113.
955:
942:
940:
937:
934:
933:
920:
902:
901:
899:
896:
895:
894:
888:
883:
881:Kammhuber Line
878:
872:
867:
860:
857:
810:
809:Countermeasure
807:
769:Bletchley Park
748:
743:
703:Heinkel He 111
679:
678:Countermeasure
676:
461:
456:
430:
429:Countermeasure
427:
337:
334:
321:Kleve (Cleves)
309:Stollberg hill
256:
251:
249:
248:German systems
246:
194:
191:
124:
121:
52:United Kingdom
28:
9:
6:
4:
3:
2:
2567:
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2440:Organisations
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2061:
2060:
2055:
2053:
2050:
2048:
2045:
2043:
2040:
2039:
2037:
2032:Campaigns and
2029:
2019:
2016:
2014:
2011:
2009:
2006:
2004:
2001:
2000:
1998:
1994:
1988:
1985:
1983:
1980:
1978:
1975:
1973:
1972:9 AA Division
1970:
1968:
1967:8 AA Division
1965:
1963:
1962:7 AA Division
1960:
1958:
1957:6 AA Division
1955:
1953:
1952:5 AA Division
1950:
1948:
1947:4 AA Division
1945:
1943:
1942:3 AA Division
1940:
1938:
1937:2 AA Division
1935:
1933:
1932:1 AA Division
1930:
1929:
1927:
1925:
1921:
1915:
1912:
1910:
1907:
1905:
1902:
1901:
1899:
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1728:
1727:
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1723:
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1716:
1712:
1706:
1703:
1701:
1700:Night fighter
1698:
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1686:
1683:
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1514:
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1466:
1463:. CRC Press.
1462:
1457:
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1439:
1432:
1427:
1420:
1415:
1408:
1403:
1396:
1391:
1384:
1379:
1377:
1369:
1364:
1358:, p. 49.
1357:
1352:
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1306:
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1164:
1158:
1151:
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1136:
1131:
1124:
1119:
1112:
1107:
1105:
1088:
1084:
1078:
1062:
1058:
1052:
1046:, p. 21.
1045:
1040:
1033:
1028:
1020:
1014:
1010:
1009:
1001:
993:
989:
983:
976:
971:
964:
959:
953:, p. 55.
952:
947:
943:
930:
924:
916:
907:
903:
892:
889:
887:
884:
882:
879:
876:
873:
871:
868:
866:
865:Belfast Blitz
863:
862:
856:
852:
850:
842:
837:
835:
831:
827:
819:
815:
806:
802:
800:
796:
792:
790:
786:
782:
778:
774:
770:
766:
762:
758:
753:
747:
742:
740:
736:
732:
727:
723:
719:
715:
712:
708:
704:
700:
695:
692:
688:
684:
675:
673:
669:
665:
661:
657:
656:Wolverhampton
653:
649:
645:
643:
638:
636:
632:
628:
624:
620:
618:
613:
609:
605:
603:
599:
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591:
587:
583:
579:
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571:
566:
563:
559:
555:
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547:
543:
539:
535:
531:
527:
523:
519:
514:
512:
508:
504:
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495:
491:
487:
483:
479:
471:
466:
460:
455:
451:
447:
444:
440:
436:
426:
424:
420:
415:
412:
408:
404:
398:
396:
392:
388:
387:amateur radio
384:
383:Hallicrafters
378:
376:
372:
366:
364:
360:
356:
351:
347:
343:
333:
329:
326:
322:
318:
314:
313:Nordfriesland
310:
306:
298:
293:
289:
285:
283:
279:
275:
266:
261:
255:
245:
242:
236:
233:
230:for taking a
229:
224:
222:
217:
215:
211:
207:
203:
200:
199:night bombing
193:Night bombing
190:
188:
182:
179:
175:
171:
166:
164:
160:
159:Lorenz system
156:
155:blind-landing
152:
148:
147:
142:
134:
129:
120:
118:
113:
111:
107:
103:
99:
95:
90:
88:
84:
80:
79:blind landing
76:
71:
69:
65:
61:
57:
53:
49:
45:
44:
39:
35:
27:
19:
2492:
2405:
2155:
2082:
2074:
2066:
2058:
1924:AA Divisions
1914:III AA Corps
1807:Organisation
1740:Cyril Newall
1730:Hugh Dowding
1612:. Retrieved
1606:
1604:Walsh, Ben.
1596:
1576:
1572:Jones, R. V.
1548:
1521:
1501:
1485:. Retrieved
1480:
1460:
1438:
1426:
1414:
1402:
1390:
1363:
1351:
1339:
1327:
1300:
1291:
1284:Hinsley 1979
1279:
1272:Hinsley 1979
1267:
1255:
1243:
1231:
1224:Hinsley 1979
1219:
1207:
1195:
1183:
1171:. Retrieved
1167:the original
1157:
1150:Hinsley 1979
1130:
1118:
1111:Hinsley 1979
1091:. Retrieved
1087:the original
1077:
1065:. Retrieved
1061:the original
1051:
1039:
1032:Hinsley 1979
1027:
1007:
1000:
991:
982:
970:
958:
946:
928:
923:
906:
853:
848:
840:
838:
825:
823:
803:
794:
793:
779:referred to
776:
772:
764:
760:
754:
750:
745:
738:
734:
730:
725:
721:
717:
716:
710:
698:
696:
690:
686:
682:
681:
667:
663:
647:
646:
642:Oberleutnant
639:
630:
626:
622:
616:
611:
607:
606:
601:
597:
593:
592:. Since the
589:
585:
581:
577:
573:
569:
567:
561:
557:
553:
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545:
541:
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477:
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469:
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432:
416:
399:
379:
367:
341:
339:
330:
304:
302:
296:
286:
281:
273:
270:
267:transmitters
264:
253:
237:
225:
218:
210:interceptors
196:
183:
167:
145:
138:
116:
114:
101:
97:
93:
91:
73:The idea of
72:
56:Air Ministry
41:
33:
31:
26:
2368:Southampton
2273:Bournemouth
2100:Beaufighter
1996:Other units
1909:II AA Corps
1789:R. V. Jones
1669:during the
1236:Goebel 2013
1173:24 February
789:Oslo Report
741:" in time.
617:Kampfgruppe
513:in France.
476:As good as
419:Butt Report
403:Rolls-Royce
346:R. V. Jones
221:blacked-out
139:Before the
133:Lorenz beam
2499:Categories
2363:Sunderland
2343:Nottingham
2328:Manchester
2268:Birmingham
2165:Chain Home
2144:Technology
2081:Operation
2073:Operation
2065:Operation
2057:Operation
2034:operations
1904:I AA Corps
1782:Scientists
1750:Keith Park
1599:. Granada.
1452:References
1443:Jones 1978
1431:Jones 1978
1419:Jones 1978
1407:Jones 1978
1395:Jones 1978
1383:Jones 1978
1368:Jones 1978
1356:Price 1977
1344:Jones 1978
1332:Price 1977
1320:Jones 1978
1305:Jones 1978
1260:Jones 1978
1248:Price 1977
1212:Jones 1978
1200:Walsh 2013
1188:Jones 1978
1135:Jones 1978
1123:Jones 1978
1044:Price 1977
975:Price 1977
963:Brown 1999
951:Price 1977
911:pronounced
870:Chain Home
785:Hans Mayer
731:Knickebein
701:-equipped
691:Knickebein
687:Knickebein
660:Birmingham
635:pathfinder
612:Knickebein
503:Knickebein
498:Knickebein
494:Knickebein
478:Knickebein
439:Knickebein
435:Knickebein
391:Avro Anson
342:Knickebein
305:Knickebein
297:Knickebein
282:Knickebein
274:Knickebein
265:Knickebein
254:Knickebein
123:Background
98:Knickebein
87:Morse code
18:Knickebein
2545:The Blitz
2358:Sheffield
2333:Newcastle
2318:Liverpool
2293:Clydebank
2239:The Blitz
2110:Hurricane
2059:Steinbock
2047:The Blitz
1567:BBC 1977)
1540:974279361
939:Footnotes
511:Cherbourg
443:diathermy
395:Y Service
235:targets.
228:astrodome
170:modulated
146:Lufthansa
106:The Blitz
94:Luftwaffe
64:Wehrmacht
43:Luftwaffe
2431:Trekking
2411:Blackout
2353:Plymouth
2348:Nuneaton
2303:Greenock
2298:Coventry
2278:Brighton
2125:Spitfire
2120:Mosquito
2093:Aircraft
2067:Crossbow
1896:AA Corps
1815:Commands
1678:Overview
1574:(1978).
1499:(1979).
1093:26 March
1067:26 March
859:See also
707:West Bay
652:Coventry
232:star fix
187:visually
2373:Swansea
2338:Norwich
2288:Cardiff
2283:Bristol
2263:Belfast
2135:Typhoon
2130:Tempest
2105:Defiant
1614:14 June
1487:13 June
849:Y-Gerät
841:Y-Gerät
799:FuG 28a
795:Y-Gerät
761:Y-Gerät
746:Y-Gerät
735:X-Gerät
718:X-Gerät
711:X-Gerät
699:X-Gerät
683:X-Gerät
648:X-Gerät
627:X-Gerät
608:X-Gerät
518:X-Gerät
486:X-Gerät
482:X-Gerät
470:X-Gerät
459:X-Gerät
325:Lörrach
317:Denmark
299:antenna
263:Map of
206:bombers
117:Y-Gerät
102:X-Gerät
2323:London
2253:Barrow
2115:Meteor
2083:Gisela
1853:Groups
1714:People
1584:
1555:
1538:
1528:
1509:
1467:
1015:
411:Merlin
363:Enigma
174:dipole
83:runway
2313:Leeds
2161:Radar
2075:Diver
929:Wotan
898:Notes
844:'
826:Wotan
781:Wōden
777:Wotan
773:Wotan
765:Wotan
729:with
668:Weser
574:Rhine
570:Weser
562:Rhine
554:Weser
546:Weser
538:range
534:Weser
522:Rhine
507:Weser
490:Weser
407:Derby
385:S-27
359:Ultra
319:; at
2308:Hull
2258:Bath
1765:Army
1616:2013
1582:ISBN
1553:ISBN
1536:OCLC
1526:ISBN
1507:ISBN
1489:2013
1465:ISBN
1175:2011
1095:2010
1069:2010
1013:ISBN
891:Oboe
739:Elbe
726:Oder
722:Elbe
658:and
602:Elbe
598:Elbe
594:Oder
590:Elbe
586:Oder
582:Elbe
578:Oder
558:Elbe
550:Oder
542:Elbe
530:Elbe
528:and
526:Oder
131:The
100:and
32:The
1722:RAF
875:GEE
839:As
830:BBC
664:KGr
631:KGr
623:KGr
619:100
596:to
588:to
311:in
216:".
2501::
1534:.
1375:^
1312:^
1142:^
1103:^
990:.
791:.
654:,
560:.
524:,
70:.
2231:e
2224:t
2217:v
2167:)
2163:(
1659:e
1652:t
1645:v
1618:.
1590:.
1561:.
1542:.
1515:.
1491:.
1473:.
1238:.
1202:.
1177:.
1097:.
1071:.
1021:.
994:.
621:(
20:)
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