Battle of the Beams - Knowledge (XXG)

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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.

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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.

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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,

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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.

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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

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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

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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.

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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.

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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.

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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.

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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

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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.

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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.

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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

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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

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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

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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,

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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

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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 1754: 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

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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

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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.

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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

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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 1986: 1981: 1976: 1971: 1966: 1961: 1956: 1951: 1946: 1941: 1936: 1931: 1631:

Site (in German) listing locations of radio beam transmitters as well as radar early-warning stations (interesting photos and extensive list of references)

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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.

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used a single narrow beam pointed over the target, similar to earlier beam systems, transmitting a modulated radio signal. The system used a transponder (

370: 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 2549: 1657: 798: 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

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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.

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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 1908: 153:

in the development of commercial aviation, and in systems and methods that would improve safety and reliability. Considerable effort went into

1903: 1585: 1556: 1529: 1510: 1468: 1016: 373:, leading scientific adviser to the government, argued that any such system would not be able to follow the curvature of the Earth, although 2514: 2229: 2191: 2002: 226:

To support this mission, the RAF invested heavily in navigation training, equipping their aircraft with various devices, including an

213: 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 284:

receivers were disguised as a standard blind landing receiver system, consisting apparently of the EBL-1 and the EBL-2 receivers.

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The British were ready for this system even before it was used. By chance, the Germans had chosen the operating frequency of the

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beam, spread along it for a few hundred yards. This was the sort of accuracy that even daytime bombing could rarely achieve. The

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and its two lobes. The "equisignal" area in the centre grows narrower, and more accurate, as the aircraft approaches the runway.

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aids which allowed aircraft to approach an airport at night or in foul weather. The primary system developed for this was the

1739: 2017: 1162: 2196: 1650: 1814: 1666: 349: 2519: 918:; 'bent leg' is the literal translation. An English speaker would use the phrase 'crooked leg' rather than 'bent leg'. 756: 81:

aid. The basic concept is to produce two directional radio signals that are aimed slightly to the left and right of a

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returned photographs of the RAF bombing raids, showing that they were rarely, if ever, anywhere near their targets.

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signal was received the clock automatically started and the two hands simultaneously swept up from zero. When the

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When the problem became widespread, the Germans introduced a new system that worked on different principles, the

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or distance the bombs would travel between release and impact, and picking a point at that range to target. The

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began to become paramount in military aviation circles. This was due to the ever-increasing performance of

2461: 1744: 532:. They were carefully aimed to define a precise bomb release trajectory. First a bomb release point along 828:

system badly. It operated at 45 MHz, which happened to be the frequency of the powerful-but-dormant

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target at night. Only the largest targets, cities, could be attacked with any probability of success.

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would be flown around the country to find the beams' location to be reported to nearby broadcasters.

358: 231: 227: 209: 67: 2099: 2056: 1923: 1832: 1827: 1822: 787:, who while visiting Norway had provided a large amount of information in what is now known as the 510: 186: 177: 144: 78: 259: 2544: 2410: 2215: 2064: 1842: 1793: 724:" which was set up to cross the 'Weser' guide beam at a mere 1 kilometre (0.6 mi) after the 410: 277: 220: 140: 2367: 2272: 2041: 1694: 1581: 1552: 1535: 1525: 1506: 1464: 1012: 890: 674:

with full support from other units dropping on their flares almost destroyed the city centre.

354: 201: 150: 1006: 165:, which was in the process of being widely deployed on large civilian and military aircraft. 2398: 2393: 2388: 2362: 2342: 2327: 2267: 2160: 2109: 2080: 1885: 1880: 1875: 1870: 1865: 1630: 874: 833: 817: 706: 650:

was used effectively in a series of raids known to the Germans as Moonlight Sonata, against

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10 kilometres (6.2 mi) before the release point, or 5 kilometres (3.1 mi) before

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used a series of beams to locate the target, each beam named after a river. The main beam,

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World War II: Western Europe: Graph to show the accuracy of night bombing of German cities

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concept that the RAF improved to great effect against the Germans some three years later.

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built huge versions of the antennas to provide much greater accuracy at long range, named

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beams on until as late as possible, making it much more difficult to arrange the "false

2415: 2352: 2302: 2297: 2277: 2134: 2129: 2114: 2051: 1500: 880: 768: 709:, Bridport. Although the aircraft sank during the recovery operation, the waterlogged 702: 671: 362: 173: 51: 1086: 1060: 276:, which means "crooked leg", although the word is also the name of a magical raven in 2498: 2425: 2372: 2337: 2287: 2282: 2262: 1699: 1496: 864: 655: 386: 382: 312: 154: 1575: 640:

The system was first tested on 20 December 1939 when a bomber from KGr 100 flown by

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system required time to implement. British intelligence at the Air Ministry, led by

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The Lorenz system worked by feeding a special three-element antenna system with a

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fought back with a variety of their own increasingly effective means, involving

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receiver from a shop in Lisle Street, London. The receiver was fitted into an

324: 86: 1539: 2322: 2238: 2170: 2046: 987: 689:. Initial defences against the system were deployed in a similar fashion to 442: 394: 280:. For the required range, transmitted power was increased considerably. The 198: 169: 105: 63: 42: 437:

headache were codenamed "Aspirin", playing on the British codename for the

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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. 780: 651: 323:

near the Dutch border, almost the most westerly point in Germany, and at

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by this time Hitler's attention was turning towards Eastern Europe.

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A Radar History of World War II: Technical and Military Imperatives

468:

Principle of the German night navigation and target-finding system

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moved their forces to the East in May 1941, in preparation for the

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system quickly, the Germans might give up on the entire concept.

2211: 1639: 1551:. Pen & Sword Military Classics. Vol. 37. Leo Cooper. 1505:. History of the Second World War. Vol. I. London: HMSO. 829: 720:

was eventually defeated in another manner, by way of a "false

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equipment to guide other aircraft to the target. To do this,

2207: 988:"knicken - Wörterbuch Deutsch-Englisch - WordReference.com" 505:

was set up at the same station to act as a guide. The main

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Military history of the United Kingdom during World War II

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Instruments of Darkness: The History of Electronic Warfare

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British monitors soon started receiving intelligence from

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5 kilometres (3.1 mi) before the release point. The

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Hermann Schmidt flew over London at 7,000m (23,000 ft).

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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

46:) used a number of increasingly accurate systems of 2439: 2381: 2245: 2179: 2143: 2092: 2030: 1995: 1922: 1894: 1851: 1813: 1806: 1781: 1763: 1720: 1713: 1677: 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 16/487 886:List of World War II electronic warfare equipment 520:used a series of three very narrow single beams, 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 8: 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 2540:Science and technology during World War II 2230: 2216: 2208: 1810: 1717: 1658: 1644: 1636: 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 1283: 1271: 1223: 1149: 1110: 1031: 943: 903: 625:100) was given the task of using their 509:antenna was set up just to the west of 1235: 348:, became aware of the system when the 40:when bombers of the German Air Force ( 1442: 1430: 1418: 1406: 1394: 1382: 1367: 1355: 1343: 1331: 1319: 1304: 1259: 1247: 1211: 1199: 1187: 1134: 1122: 1043: 974: 962: 950: 913: 7: 759:referring to a new device known as 685:proved more difficult to stop than 536:was determined, by calculating the 307:transmitters was set up in 1939 on 214:the bomber will always get through 25: 1083:"Dutch site mentioning locations" 662:. In the raid on Birmingham only 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 189:except in the worst conditions. 2555:World War II German electronics 2192:RAF strategic bombing offensive 176:, which had a slightly longer 1: 2197:United States Army Air Forces 1163:"Hallicrafters S-27 receiver" 1011:. Pen and Sword. p. 15. 60:jamming and deception signals 1667:Air Defence of Great Britain 1563:(Expanded from Episode 1 of 361:intelligence from decrypted 350:Royal Aircraft Establishment 62:. The period ended when the 2018:Women's Auxiliary Air Force 2003:Battle of Britain airfields 568:As the bomber followed the 2571: 2515:Electronic countermeasures 1565:The Secret War (TV series) 832:television transmitter at 775:. The specialist realised 68:attack on the Soviet Union 36:was a period early in the 2482:Women's Voluntary Service 421:proved this to be wrong; 50:for night bombing in the 1690:Royal Canadian Air Force 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: 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: 1718: 1671:Second World War 1660: 1653: 1646: 1637: 1619: 1617: 1615: 1600: 1591: 1562: 1543: 1516: 1492: 1490: 1488: 1474: 1446: 1440: 1434: 1428: 1422: 1416: 1410: 1404: 1398: 1392: 1386: 1380: 1371: 1365: 1359: 1353: 1347: 1341: 1335: 1329: 1323: 1317: 1308: 1302: 1296: 1293: 1287: 1281: 1275: 1269: 1263: 1257: 1251: 1245: 1239: 1233: 1227: 1221: 1215: 1209: 1203: 1197: 1191: 1185: 1179: 1178: 1176: 1174: 1165:. 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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: 1603: 1594: 1588: 1577:Most Secret War 1570: 1559: 1546: 1532: 1519: 1513: 1495: 1486: 1484: 1477: 1471: 1458: 1454: 1449: 1441: 1437: 1429: 1425: 1417: 1413: 1405: 1401: 1393: 1389: 1381: 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: 1004: 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: 2568: 2566: 2558: 2557: 2552: 2547: 2542: 2537: 2532: 2527: 2522: 2517: 2512: 2507: 2497: 2496: 2488: 2487: 2485: 2484: 2479: 2474: 2469: 2464: 2459: 2454: 2449: 2443: 2441: 2437: 2436: 2434: 2433: 2428: 2423: 2418: 2416:Baedeker Blitz 2413: 2408: 2403: 2402: 2401: 2396: 2385: 2383: 2382:Related topics 2379: 2378: 2376: 2375: 2370: 2365: 2360: 2355: 2350: 2345: 2340: 2335: 2330: 2325: 2320: 2315: 2310: 2305: 2300: 2295: 2290: 2285: 2280: 2275: 2270: 2265: 2260: 2255: 2249: 2247: 2243: 2242: 2237: 2235: 2234: 2227: 2220: 2212: 2203: 2202: 2200: 2199: 2194: 2189: 2183: 2181: 2180:Related topics 2177: 2176: 2174: 2173: 2168: 2158: 2153: 2147: 2145: 2141: 2140: 2138: 2137: 2132: 2127: 2122: 2117: 2112: 2107: 2102: 2096: 2094: 2090: 2089: 2087: 2086: 2078: 2070: 2062: 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: 1928: 1926: 1920: 1919: 1917: 1916: 1911: 1906: 1900: 1898: 1892: 1891: 1889: 1888: 1883: 1878: 1873: 1868: 1863: 1857: 1855: 1849: 1848: 1846: 1845: 1840: 1835: 1830: 1825: 1819: 1817: 1808: 1804: 1803: 1800: 1799: 1797: 1796: 1791: 1785: 1783: 1779: 1778: 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: 1697: 1692: 1687: 1681: 1679: 1675: 1674: 1665: 1663: 1662: 1655: 1648: 1640: 1634: 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: 1264: 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: 24: 14: 13: 10: 9: 6: 4: 3: 2: 2567: 2556: 2553: 2551: 2548: 2546: 2543: 2541: 2538: 2536: 2533: 2531: 2528: 2526: 2523: 2521: 2518: 2516: 2513: 2511: 2508: 2506: 2503: 2502: 2500: 2493: 2483: 2480: 2478: 2475: 2473: 2470: 2468: 2465: 2463: 2460: 2458: 2455: 2453: 2450: 2448: 2445: 2444: 2442: 2440:Organisations 2438: 2432: 2429: 2427: 2424: 2422: 2419: 2417: 2414: 2412: 2409: 2407: 2404: 2400: 2397: 2395: 2392: 2391: 2390: 2387: 2386: 2384: 2380: 2374: 2371: 2369: 2366: 2364: 2361: 2359: 2356: 2354: 2351: 2349: 2346: 2344: 2341: 2339: 2336: 2334: 2331: 2329: 2326: 2324: 2321: 2319: 2316: 2314: 2311: 2309: 2306: 2304: 2301: 2299: 2296: 2294: 2291: 2289: 2286: 2284: 2281: 2279: 2276: 2274: 2271: 2269: 2266: 2264: 2261: 2259: 2256: 2254: 2251: 2250: 2248: 2244: 2240: 2233: 2228: 2226: 2221: 2219: 2214: 2213: 2210: 2198: 2195: 2193: 2190: 2188: 2185: 2184: 2182: 2178: 2172: 2169: 2166: 2162: 2159: 2157: 2154: 2152: 2149: 2148: 2146: 2142: 2136: 2133: 2131: 2128: 2126: 2123: 2121: 2118: 2116: 2113: 2111: 2108: 2106: 2103: 2101: 2098: 2097: 2095: 2091: 2085: 2084: 2079: 2077: 2076: 2071: 2069: 2068: 2063: 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: 1897: 1893: 1887: 1884: 1882: 1879: 1877: 1874: 1872: 1869: 1867: 1864: 1862: 1859: 1858: 1856: 1854: 1850: 1844: 1841: 1839: 1836: 1834: 1831: 1829: 1826: 1824: 1821: 1820: 1818: 1816: 1812: 1809: 1805: 1795: 1792: 1790: 1787: 1786: 1784: 1780: 1774: 1771: 1770: 1768: 1766: 1762: 1756: 1753: 1751: 1748: 1746: 1743: 1741: 1738: 1736: 1733: 1731: 1728: 1727: 1725: 1723: 1719: 1716: 1712: 1706: 1703: 1701: 1700:Night fighter 1698: 1696: 1693: 1691: 1688: 1686: 1683: 1682: 1680: 1676: 1672: 1668: 1661: 1656: 1654: 1649: 1647: 1642: 1641: 1638: 1632: 1629: 1628: 1624: 1609: 1608: 1602: 1598: 1593: 1589: 1583: 1579: 1578: 1573: 1569: 1566: 1560: 1554: 1550: 1545: 1541: 1537: 1533: 1527: 1523: 1518: 1514: 1508: 1504: 1503: 1498: 1494: 1483: 1482: 1476: 1472: 1466: 1463:. CRC Press. 1462: 1457: 1456: 1451: 1444: 1439: 1436: 1432: 1427: 1424: 1420: 1415: 1412: 1408: 1403: 1400: 1396: 1391: 1388: 1384: 1379: 1377: 1373: 1369: 1364: 1361: 1358:, p. 49. 1357: 1352: 1349: 1345: 1340: 1337: 1333: 1328: 1325: 1321: 1316: 1314: 1310: 1306: 1301: 1298: 1292: 1289: 1285: 1280: 1277: 1273: 1268: 1265: 1261: 1256: 1253: 1249: 1244: 1241: 1237: 1232: 1229: 1225: 1220: 1217: 1213: 1208: 1205: 1201: 1196: 1193: 1189: 1184: 1181: 1168: 1164: 1158: 1155: 1151: 1146: 1144: 1140: 1136: 1131: 1128: 1124: 1119: 1116: 1112: 1107: 1105: 1101: 1088: 1084: 1078: 1075: 1062: 1058: 1052: 1049: 1046:, p. 21. 1045: 1040: 1037: 1033: 1028: 1025: 1020: 1014: 1010: 1009: 1001: 998: 993: 989: 983: 980: 976: 971: 968: 964: 959: 956: 953:, p. 55. 952: 947: 944: 938: 930: 924: 921: 916: 907: 904: 897: 892: 889: 887: 884: 882: 879: 876: 873: 871: 868: 866: 865:Belfast Blitz 863: 862: 858: 856: 852: 850: 842: 837: 835: 831: 827: 819: 815: 808: 806: 802: 800: 796: 792: 790: 786: 782: 778: 774: 770: 766: 762: 758: 753: 747: 744: 742: 740: 736: 732: 727: 723: 719: 715: 712: 708: 704: 700: 695: 692: 688: 684: 677: 675: 673: 669: 665: 661: 657: 656:Wolverhampton 653: 649: 645: 643: 638: 636: 632: 628: 624: 620: 618: 613: 609: 605: 603: 599: 595: 591: 587: 583: 579: 575: 571: 566: 563: 559: 555: 551: 547: 543: 539: 535: 531: 527: 523: 519: 514: 512: 508: 504: 499: 495: 491: 487: 483: 479: 471: 466: 460: 457: 455: 451: 447: 444: 440: 436: 428: 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: 335: 333: 329: 326: 322: 318: 314: 313:Nordfriesland 310: 306: 298: 293: 289: 285: 283: 279: 275: 266: 261: 255: 252: 247: 245: 242: 236: 233: 230:for taking a 229: 224: 222: 217: 215: 211: 207: 203: 200: 199:night bombing 193:Night bombing 192: 190: 188: 182: 179: 175: 171: 166: 164: 160: 159:Lorenz system 156: 155:blind-landing 152: 148: 147: 142: 134: 129: 122: 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: 549: 545: 541: 537: 533: 529: 525: 521: 517: 515: 506: 502: 497: 493: 489: 485: 481: 477: 475: 469: 458: 452: 448: 438: 434: 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 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 18:Y-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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