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World War II air campaign -- British Chain Home Network
World War II Air Campaign: Battle of Britain Technology--British Chain Home Network
Figure 1.--Radar was the most public 'secret' weapon in the history of warfare. It could not be hidden. The Germans knew about it and actually were technologically on the same plane as the British. The Luftwaffe wgen they launched the Battle of Britain after losing a few Stukas, simply ignored the Chain Home stations. Despite the fabeled Spitfire, the RAF could not have won the Battle of Britain without the Chain Home Network--it was the most powerful assett the RAF had. Without radar, the advantage in air combat swings heavily to the attacking force. This is the RAF Bawdsey in Suffolk. It was erected in 1938 and Britain's first operational Chain Home radar station. You can clearly see the eight tall masts, four for transmitting and four for receiving. The British radar research group that developed the Chain Home system was located here, but after Hitler and Stalin launched the War, the researchers moved to Dundee in Scotland, a safer zone (September 1939). It is now being restored by a preservation group. Looking at what radars required in 1939, you can see at a glance the vital importabce of the cavity magnitron which allowed the priduction of much smaller radar sets. .
The origins of the British Chain Home Network (CHN) lie in the German World War I Zeppelin raids on London and other British cities. In a twist of history, had the Germans not used the Zeppelins to raid British citiesm the CHN probably would not have been built and the Luftwaffe would have won the Battle of Britain. A Brirish researcher, Sir Robert Watson-Watt, working on thunder storms began using primitive radar. He notice that his experiments were spoiled when a plane flew by. This was not a major new discovery. Reserachers had noticed this phenomenon before Workd War I, but had no instruments to measure it. The Air Minisry concernd about possible bomber attacks, immediately latched on to Warson-Watt's work on Radio Directional Finding (RDF) The British were not the only country working on radar. Most contries with an air force, including the Germans, were researching it. The British with their fear of bombing, thanks to the Germans World War I raids, commited real resources to it. The result was the Chain Home Network (CH) which was operational along the British coast by 1940. A critical mistake made by the Luftwaffe was their failure to appreciate the critical importance of the British CH network. CH was a network of 52 overlapping radar stations from Pembrokeshire to the Falklands. [Davidson, p. 415.] This was the beginning of the so called Battle of the Beams and it was to have a major impact on the outcome of the Battle of Britain. Radar was not unknown to the Luftwaffe, but in 1940 they failed to fully appreciate its significance. The Germans were much less interested in radar at the time because they were primarily focused on offensive opeations and ground support. Radar at the time did not offer much that could contribute to that mission. The CH network allowed the RAF to effectively use its numerically inferrior forces to best advantage, in effect manifying the force. [Brown] Without radar, the RAF would have required a much larger fighter force than it had so it could maintain aerial patrols. The British CH network could follow Lufwaffe raiders while they were still forming up over France and then crossing the Channel. It was, however, an outward looking system. Once the Germans were overland, the RAF had to rely on ground observers to track the German planes. The radar could identify RAF planes with IFF, but only about a third of the RAF fighters were so equipped when the Battle of Britain began. The British defense was conducted from Oxbridge where the reports from the radar stations and ground observers were collected and evaluated so orders could bev issued to RAF Fighter Command. The Germans were aware of the CH network, although they did not fully appreciate its value. At an early stage of the Battle of Britain, the Luftwaffe went after the CH towers, but they proved difficult targets, especially as the RAF fighters savaged the slow-flying Stukas JU-87. The JU-87 was an effective ground support dive bommber and could have taken out the towers, but was vulnerable to modern fighters. They could be used only where the Luftwaffe had achieved aerial supperiority. After several JU-87 Stuka squadrons were devestated by FAF fighters, they were withdrawn from the campaign. And when the Germans did manage to hit a CH tower, they noted little impact. The CH towers wre overlapping. In addition, the British has mobile units ready to plug any gaps which the German bombers may have created. The Lufwaffe thus early on gave up even targetting the CH towers. It was one of a series of mistakes.
The origins of the British Chain Home Network (CHN) lie in the German World War I Zeppelin raids on London and other British cities. The damage inflictd was modest in World war II terms, but it was enough to shock Britainto its core. It was one thing for sholders to fall in cobat, it was quie another fr inncent school hildren to be killd in the niddle of London. In a twist of history, had the Germans not used the Zeppelins to raid British citiesm the CHN probably would not have been built and the Luftwaffe would have won the Battle of Britain.
Weather Research
A Brirish researcher, Sir Robert Watson-Watt, working on thunder storms began using primitive radar. He notice that his experiments were spoiled when a plane flew by. This was not a major new discovery. Reserachers had noticed this phenomenon before Workd War I, but had no instruments to measure it. The Air Minisry concernd about possible bomber attacks, immediately latched on to Warson-Watt's work on Radio Directional Finding (RDF).
German Research
The British were not the only country working on radar. Most contries with an air force, especially the Germans, were researching it. And if anything, the Gerams understanding of radar vwas more advanced than the British. The British with their fear of bombing, thanks to the Germans World War I raids, commited real resources to bulding an integrated air drfense syste, It is theChain Home system nit just radar that made all the fiiference. The Germans were not all that concerned about potenial Allied bombing raids, there primary focus was on attack. And they saw little use of radar in an offensive capacity. The first German use of radar was by the Navy. They equipeed their capital ships like Bismarck with radar gun ranging systems. It was one reason why HMS Hood was hit and destroyed (March 1941). And as the tide of war shifted, the Germans would employ advanced radars as part of their highly effective air defense system. But what the Germans did not have was the cavity magnitron, enabling radars to be installed on small boats and aircraft. The cavity magnitron did not oplay a role in the Battle of Britain, but it would later in the WArm especilly bwhen American companies made impriovemrnts and began mass producing producing it.
Committee for Scientific Study of Air Defense -- CSSAD (1934)
The British after World War I cut defense spending to the bone. And there was no sesire to increase 'wasteful' military spending. Even after Hitler seized power (1933), there was no substantial increase in defense spending. Yet the developments in Germny could not be ignored. Reports reached Britan thast the NAZIs were building an airforce in violation of the Versailles Treaty. The Britoish hd been subjected to German bombing in World war I and were desperate to defend their cities. The Royal Air Force (RAF) staged a mock aerial bombing raid on London. The results showed that the FAD could not prevent the bombing of the capital. The Government ecided to establish a Committee for Scientific Study of Air Defense (CSSAD) would be established to help prepre an air defense system (1934). Henry Tizard, a former military pilot and chair of the Aeronautical Research Committee, was chosen to head it. CSSAD is sometimes referred to as the Tizard Committee. A year later, Hitler reintroduced concription and announced the existemnce of the Luftwaffe did alarm bells go off in Whitehall. There was no massive effort to mtch German military spending, but some measures were taken. The British Government and British people were desperate to avoid another dreadful War. Hitler was, however, determined to have one. The British did not accuratlely assess Hitler's character. They simply could not believe that any sane leader would want another War.
System
The result was the Chain Home Network (CH) which was operational along the British coast by 1940. CH was a network of 52 overlapping radar stations from Pembrokeshire to the Falklands. [Davidson, p. 415.] This was the beginning of the so called Battle of the Beams and it was to have a major impact on the outcome of the Battle of Britain. CH was the first radar system to be arrayed into a complete air defence system, And it was tested in combat operations soon fter it completion.
It was not the technology that was innvative. The Germns had basically the sae radar technology, kn sme cases more advanced than the British. What was innivative about the CH system was that it was a network. Watson-Watt and his associates used the existing, actually rather riitive radaar technology, to create what prived to be a critically important air defence network.
Value
The Germans had waged a series of campigns before the Battle of Britain. And a key component of these campaigns was an early strike designed to destoy their opponents' air force on the ground at the onset of the campaign. This enabled them to knock out the Polish, Dutch, and Belgian Air Forces with ease. The French avoided this, but onky by dispering theiur air force. This meant, however, that when the Germans struck in the Ardennes, a powerful air response was impossibe. Without radar the only way to try to prevent this was to deploy most of your force in air patrols. The force needed for effective patrols was astronomical. And as a result, the early German strikes proved highly effective. And as the Luftwaffe commanders prepared fr the Battle of Britain, they expected to find the RAF as sitting ducks on their air fields. The CH network allowed the RAF not only to get their fighters off thge ground in time, but to effectively use its numerically inferrior forces to best advantage, in effect manifying the force. [Brown] Without radar, the RAF would have required a much larger fighter force than it had so it could maintain aerial patrols. The British CH network could follow Lufwaffe raiders while they were still forming up over France and then crossing the Channel and give vital advanced warning to RAF fighter squadrons. The advanved warning was vital, but not only to avaoid being destoyed on the ground. It gave RAF fighters indescpensible offendsive advantages. The RAF fighters not only needed advanced waening to get airborn, they needed it to gain alditude which was vital. Succcess in air combat for reasonably matched forces is heavily depndent on aldiutude (which can be converted into air speed) and surpreise. These two factoes ourweigh nunbers, especually as the RAF pilots could fly more missions than the Germans who have to cross the channel and have significant fuel limitations. It was as the British say, a 'close run thing' The CH network gave the 11 Group squadrons 20 minutes warnings. It might take 4 minites to scanmble and 13 minutes to gain operational height. (The Spitfires could climb much faster than the Hurricanes.) But if you had height and could dive on your opponent, you had a real advantage. And the CH warning not only helped the RAF to gain height, but could vector the fighters on to the German formations. This should not be overstrsses. The RAF squadronds did bot always gain alditude and position. But they did often enough to deal with a much larger German force, protected by the exccellent Me-109 fighter and skilled, more experienced pilots. The CH Network was not perfect, it was still a fairly primitive system. The CH Network was an outward looking system. Once the Germans were overland, the RAF had to rely on ground observers to track the German planes. And there was no way to desguise the towers as you can see here (figure 1). They were starkly visible. Incredavly after a few dislutory attacks, the Lufwaffe made not real effort to destroy the CH Network. The CH Netoek was the the mist effective assett the RAF had and the Luftwaffe essebtially ignored it. This may be the greatest mnistake of the War, but the vulnerability of the system is often overstated. And it should be stressed that radar was only part of it. The observer corps was also vital. As was the integrated nature of the system, the ability of the vBritish not bobly to acquire information on the German intrudersm, bit to ger that information and instructions to the fighter squadrons. .
IFF
The CH researchers at Bawdsey Research Station realized even before the War that the radar did not differentiate between RAF and enemy planes. The grond observers who were part of the system helped, but an electronic systm was badly needed. The answer was Identification Friend or Foe (IFF). Despite what was indicatedby the name. IFF could only positively identify friendly targets. If an IFF interrogation received no reply or an invalid reply, the trget plne or squadorn could not be definatively identified as friendly, but the strong presumption is that they were enemy aircraft. There were many reasons that friendly aircraft would not properly respond to IFF interogations. The RAF IFF was the world's first such system. The CH radars could identify RAF planes with IFF, but only about a third of the RAF fighters were so equipped when the Battle of Britain began.
Network System
The British defense was conducted from Oxbridge where the reports from the radar stations and ground observers were collected and evaluated so orders could be issued to RAF Fighter Command. CH was designed to controllg the airspace around the British Isles from northern Scotland to the southern coast of England. The network included dedicated buried land-line telephones to collect information from Chain Home (CH) radar stations and the Royal Observer Corps (ROC). The infrmatin gathered was then used to vector figters used as interceptors toward the ncoming German fighter and bomber squadrons. There was also anti-aircraft artillery, but it ws the fighters hat were the really effective force.
Luftwaffe Tactical Decision
Virtually every assessment of the Battle of Britain concludes that the Luftwaffe made a critical mistake by failing to appreciate the critical importance of the British CH network. Radar was not unknown to the Luftwaffe, but in 1940 they failed to fully appreciate its significance and the value of an integtated air defense system. The Germans were much less interested in radar at the time because they were primarily focused on offensive opeations and ground support. Radar at the time did not offer much that could contribute to that mission. The Germans were aware of the CH network, although they did not fully appreciate its value. At an early stage of the Battle of Britain, the Luftwaffe went after the CH towers, but they proved difficult targets, especially as the RAF fighters savaged the slow-flying Stukas JU-87 that had the accuracy to needed to hit the stations. The JU-87 was an effective ground support dive bommber and could have taken out the towers and other targeted facvilities, but was vulnerable to modern fighters. They could be used only where the Luftwaffe had achieved aerial supperiority. After several JU-87 Stuka squadrons were devestated by RAF fighters, they were withdrawn from the campaign. And when the Germans did manage to hit a CH tower, they noted little impact. The CH towers were overlapping. In addition, the British has mobile units ready to plug any gaps which the German bombers may have opened. The Lufwaffe thus early on gave up even targetting the CH towers. It was one of a series of mistakes. It should also be stressed that the stations were a difficult target. Without the Stukas, a huge effprt would have been needed to destroy the system. Now with the towers, the statiions were easy to nidentify, but aking out a tower was n=much more difficult than it might seem. The lattice structure of a tower mean that it would only be taken down by a direct hit on the sbase supports. The blast force of even a near miss would just pass through it. The Germans were intent on getting at the RAF airfields and aircrafy. Expending a major effort on the CH statioins was dismissed as a diversion from the principoal station. Notice that with the Allied strategic bombing campaign, the German air defense radars were not a major target.
British Diusinformatioin
The Air Ministry realized that they could not hide the radar towers and that they coukd be attacked. So they decided in a disinformatiin campaign. Although not commionly mentiioned, it was one of the misdt successful of the War. The Ministry simply ignored the towers and any mention of radar and the Chain Home System. Even the RAF pilots knew nothing about radar. The Ministry believed that radar was a great British secret. The Germans were actually more advanced in radar technology than the British, but thev KLuftwaffe was notg all that interested in it. It did not seem to have offensive valjue. What was different about the Chin Home Network was integrating radar into a comprehensive air defense system. The Ministry released movie news reels about preparations for air defense. There was no n=mebtiin oif radar or the Chain Home Network. The news reel segmebnts showed the RAF flying aerial patrols as the major factor in Britain's air defense system. This seems to have dustracted the Germans. Aerial patrols were inefficte and wasteful which was shown in efforts to defeat the German Western Offensive (May 1940). Downing knew this which is why the Chain Hiome Network was created. The Germans seemed to assume that what they confronted over France would be what they would confrint over Britain.
While the Battle of Britain was raging, Primeminister Churchill dispached the Tizard Mission to America with the assignment to turn over Britain's secret weapons technology to America--whout any strings. One observer described the unobrtusive black metal box as the most valuablke cargo ever arriving on merica shores. Churchill was hoping tht American industry could manufacture these weapons system to help supply British frces. In the back of his mind, however, he had to be thinking that Britain might fail and at least the weapons would be in the hanbds of the americans to contnue the defense of Western civilization. This was in sharp contrast to the direction that the French took. Interestingly, radar technology and the CH network was not one of the items that impressed the Americans. The British technology id enable the United states to make subtantial advances in its radar work. In fact a radar warning system was set up on northern tip of Ohau spotted the first wave of Japanese aircraft headed for Pearl Harbor (December 7, 1941). It was, however, still experimental, and the plot was dismissed.
Sources
Brown, Louis. A Radar History of World War II (IOP Publishing, 1999).
Davidson, Eugene. The Umaking of Adolf Hitler (Univesity of Missouri: Columbia, 1996), 519p.
