Adlertag

• 1. Eagle Day

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  Adlertag, German for Eagle Day, was the opening day of Unternehmen Adlerangriff, or Operation Eagle Attack, the Luftwaffe's plan to destroy Britain's Royal Air Force. Reichsmarschall Hermann Göring had promised Hitler results within days, or at worst within weeks. The attack followed Britain's refusal of every overture toward a negotiated peace. It was meant to mark the beginning of the end for RAF Fighter Command. It did not. Neither Adlertag nor the operations after it gave Germany the control of the sky that it needed. How did a plan so confidently sold to Hitler fall short? What did the attackers misjudge about the force they were hunting? And what did the failure do to Germany's hopes of invading Britain?

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• 2. The Road To Adlertag

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  France surrendered on the 25th of June 1940, after a German offensive that had begun on the 10th of May. The British Expeditionary Force had escaped encirclement at Dunkirk, and Paris fell on the 14th of June. Hitler hoped Britain would now accept an armistice, and he was ready to offer generous terms. The Churchill coalition government turned down his tentative offers.

  On the 16th of July 1940, Hitler issued Directive No. 16, ordering provisional preparations to invade Britain. The invasion was codenamed Operation Sea Lion, or Unternehmen Seelöwe. A landing fleet would be exposed, so the Luftwaffe first had to destroy the RAF. Otherwise British fighters could attack the fleet or protect the Royal Navy's Home Fleet, which might try to stop a landing. Göring and Hitler even hoped that crushing the RAF would make an invasion unnecessary. On the 1st of August, Hitler gave Göring and the Luftwaffe high command Directive No. 17, covering air and sea warfare against England.

  The essential target was RAF Fighter Command. Without it, Britain would lose its main defence in the air, and a country feeling vulnerable to bombing might choose to negotiate.

  More than 1,400 aircraft had been lost in the Battle of France, on top of about 500 lost over Poland in 1939 and Norway in 1940. The Luftwaffe had to wait until its strength recovered. Meanwhile, the Kanalkampf, or Channel battle, ran from the 10th of July to the 8th of August 1940. It targeted British convoys in the Channel in the hope of tempting RAF fighters into combat. Attacks on shipping sank only 24,000 tons, while aircraft-laid mines sank 38,000 tons. Fighter Command lost 74 pilots killed or missing and 48 wounded in July. Even so, its strength rose to 1,429 by the 3rd of August, leaving it short by only 124 pilots.

  Bad weather forced the Germans to postpone the main assault several times before it went ahead on the 13th of August 1940. The Luftwaffe began that day with 71 percent of its bombers, 85 percent of its Bf 109 units and 83 percent of its Bf 110 units operational. German air strength had been judged acceptable only by the 12th of August, and the raid flown that day would test the picture the planners were relying on.

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• 3. Blind Spots

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  The first major German raid on RAF airfields inland came on the 12th of August 1940. Its targets included RAF Hawkinge, Lympne and Manston, radar stations at Pevensey, Rye and Dover, and the docks at Portsmouth. The radar station at Ventnor was badly damaged, but everything that was hit was working again by the following morning. Lympne, unknown to German intelligence, was not even an operational station.

  British codebreaking was starting to pull ahead of its German counterpart. The Enigma machine had been broken, and poor Luftwaffe signals discipline gave the British easy access to German radio traffic. The effect of Ultra on the Battle of Britain is disputed, and the Official Histories claim it had no direct impact. Still, Ultra and the Y service gave the British an increasingly accurate picture of where German units were deployed.

  On Adlertag itself, the Luftwaffe made repeated errors in identifying airfields. It treated bases belonging to RAF Coastal Command and RAF Bomber Command as Fighter Command stations. Destroying most of the targets on its list would not have weakened Fighter Command in the slightest.

  Joseph "Beppo" Schmid, head of the Luftwaffe's Military Intelligence Branch, produced a string of flawed reports. In July 1940 he badly overstated German strength and understated the RAF. He estimated that Britain could build only 180-330 fighters a month, when the true figure was 496, and he said that number would fall. That suggested the RAF could not survive a long battle of attrition. He described British command as rigid, with fighters tied to their home bases. He left out the maintenance and organisation work that put damaged aircraft back in service quickly, and he expected a short battle. Crucially, he failed to mention radar at all.

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• 4. The Dowding System

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  Air Chief Marshal Sir Hugh Dowding, who commanded RAF Fighter Command, gave his name to the system that ran the British defence. He modernised an arrangement first created from 1917 by Major General E B Ashmore. Dowding himself pushed for the use of Radio Direction Finding, known as RDF or radar. The name was chosen to be vague on purpose, so the enemy would not understand the system if it ever came to light.

  Chain Home RDF stations stood along Britain's coasts. They could often detect Luftwaffe formations while the aircraft were still assembling over their own airfields in northern France and Belgium. Once raiders passed inland beyond the radar stations, the Royal Observer Corps took over the plotting. Reports went to the main operations room at Fighter Command headquarters, RAF Bentley Priory, where each plot was judged to be hostile or friendly. Hostile plots went to a large underground bunker.

  There, members of the Women's Auxiliary Air Force took course information by telephone and plotted each raid. Colour-coded counters represented the raids on a large table with a map of Britain laid over a grid. Magnetic rakes pushed the counters along as the raiders moved, and the colour showed how old the information was. The Fighter Controller and Dowding could see where each formation was heading, at what height and in what strength. The simplicity of the arrangement meant decisions could be made fast. The Y Service radio posts and the Ultra centre at Bletchley Park added intelligence on the German order of battle.

  The same information went to the headquarters of each group, where a filter room cross-checked it. Group had tactical control of the battle, so its operations room, also in a bunker, showed the group area and its airfields. The duty fighter controller was the group commander's personal representative and decided how and when each raid would be met. If the telephone lines failed, engineers were on site within minutes.

  Because the Germans never mounted a sustained, concentrated campaign against the radar stations, their warnings kept helping to direct RAF units at the right moments. On Adlertag, though, the first trouble for the defenders came from a mistake in the Luftwaffe's own orders.

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• 5. Orders That Never Arrived

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  At 04:50 on the morning of the 13th of August 1940, the Dornier Do 17s of KG 2 took off for their target, unaware that Göring had postponed the day's raids because of bad weather. Their escorts from ZG 26 had received the cancellation. Some of that wing were already airborne under Oberstleutnant Joachim Huth, and he tried to warn the bombers. Unable to reach them by radio, Huth flew in front of the formation and performed aerobatics. Geschwaderkommodore Johannes Fink, leading KG 2, ignored him.

  Albert Kesselring had ordered bombers to abandon missions if their escorts failed to appear. Fink did not want to be accused of disobeying orders, so he pressed on even after the Bf 110s turned back. The route to Eastchurch airfield on the Isle of Sheppey ran around the coast. The way home would cross No. 11 Group's territory, which could have been disastrous without escorts. Yet low cloud led the Observer Corps to misjudge the bombers' direction, and radar did not pick up their approach. The WAAF plotted the raid wrongly, and the RAF failed to stop the attack.

  KG 2 claimed ten Spitfires destroyed on the ground. In fact, no Fighter Command fighters were lost. RAF Eastchurch belonged to Coastal Command, which lost five Bristol Blenheims and one Spitfire, and 16 of its personnel were killed. Much equipment and ammunition was destroyed, but the station was back in operation by 16:00.

  The bombers were eventually intercepted. KG 2 lost five Do 17s, and six more were badly damaged. Accurate fire from the Dornier gunners brought down two Hurricanes from the squadrons that attacked, which included No. 111, No. 151 and No. 74. Adolph Malan led No. 74 Squadron and shot down one Do 17 himself. German crews lost 11 killed in action and nine taken prisoner. The false claim of destroyed Spitfires convinced German intelligence that Eastchurch was a fighter station, and the Luftwaffe launched seven fruitless raids on it in the coming weeks.

  The confusion was not confined to one wing. Luftflotte 2 received the order to abandon morning operations, and KG 76 dropped its attack on Debden but struck Kenley and other airfields in Kent and Essex. KG 27 abandoned most of its missions, though III./KG 27 pressed on toward Bristol and lost one He 111 to No. 87 Squadron.

  At Luftflotte 3, commander Hugo Sperrle never received the cancellation and ordered attacks to begin. At 05:00, 20 Ju 88s of I./KG 54 took off for the Royal Aircraft Establishment's airfield at Farnborough. Five minutes later, 18 Ju 88s of II./KG 54 left for RAF Odiham. At 05:50, 88 Ju 87s of StG 77 headed for Portland Harbour. About 60 Bf 110s and 173 Bf 109s escorted them. Cloud hid StG 77's target, but KG 54 pressed on and RAF fighters from Northolt, Tangmere and Middle Wallop intercepted. Four Ju 88s and one Bf 109 were shot down. The Germans claimed 20 RAF fighters, but only three were lost and three pilots wounded, with none killed.

  ZG 2 later arrived over Gosport without the Ju 88s it was meant to escort, because those bombers had been ordered to stand down. No. 238 Squadron shot down one of the Bf 110s. At 11:10, 23 Bf 110s of V./LG 1 took off ahead of a raid by KG 54 that had already been cancelled, possibly to tempt the RAF out of position. Nobody told them, and they continued to Portland. There they met the Hurricanes of No. 601 Squadron and lost six Bf 110s destroyed and three damaged. Other accounts give lower figures. The Zerstörergeschwader claimed 30 RAF fighters destroyed while reporting a loss of 13 of its own.

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• 6. Afternoon Raids

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  The official go-ahead for renewed attacks came at 14:00. At 15:30, between 58 and 80 Ju 88s of LG 1, escorted by 30 Bf 110s, took off to bomb Boscombe Down and Worthy Down. RAF Andover was also to be hit, and 52 Ju 87s from StG 1 and StG 2 were to strike Warmwell and Yeovil. I./JG 53 swept ahead from Poole to Lyme Regis to tempt the RAF into battle. The sweep drew no fighters away and only alerted the defences five minutes early. When the main waves reached the coast, 77 RAF fighters were waiting, and the whole of No. 10 Group intercepted.

  No. 609 Squadron hit one Staffel of II./StG 2 so hard that six of its nine Ju 87s were shot down. Cloud made StG 1 and StG 2 give up their original targets, and both headed for Portland. I./LG 1 abandoned Boscombe Down and bombed Southampton instead. No. 238 Squadron was sent to intercept, but the fighter escort was too strong. III./LG 1 dropped bombs near RAF Middle Wallop by mistake, and only Andover airfield was hit, a station used for bombers rather than fighters.

  The Southampton raid destroyed a bicycle factory, a furniture warehouse and a refrigerated meat depot. Fires were under control by dusk. Luftwaffe intelligence had not recognised the Spitfire factory on the waterfront near the docks as important, and believed it built bombers. It was attacked and severely damaged only in September, and even then the Germans did not grasp what they had done to Spitfire production. The factory was later broken up and production dispersed.

  StG 77 failed to find RAF Warmwell and dropped its bombs at random, escaping notice while other Ju 87 units drew the attention of the defenders. Erprobungsgruppe 210 took off at 15:15 for targets near Southend, escorted by ZG 76. Finding unbroken cloud over Essex, it dropped its bombs on Canterbury.

  RAF Detling suffered the worst. Ju 87s of IV./LG 1 bombed the station while 40 Bf 109s strafed it, and the operations block was hit. Group Captain E P Meggs-Davis, the station commander, was killed, along with a Squadron Leader named J.H Lowe. Two others were wounded, one of them the First World War ace Robert J. O. Compston. The station's casualties came to 24 killed and 42 wounded, and No. 53 Squadron lost a number of Blenheims on the ground. Detling was not a Fighter Command station, so the attack did not affect No. 11 Group in any way.

  In the afternoon, 80 Do 17s of KG 3 headed for Eastchurch and the Short Brothers factory at Rochester. JG 51, JG 52, JG 54 and 60 Bf 109s from JG 26 escorted them, some 270 aircraft in all. III./KG 3 attacked Eastchurch, while II./KG 3 went on to Rochester and did significant damage to the factory producing the Short Stirling heavy bomber. Eight RAF squadrons intercepted, among them No. 3, No. 64, No. 234 and No. 249. JG 26's account says the British fighters made little impression on the bombers. Three JG 51 Bf 109s were shot down.

  RAF Bomber Command also fought that day. Air Officer Commanding Charles Portal had protested against the pointlessness of raiding airfields in Scandinavia, but the Air Ministry insisted. No. 82 Squadron sent twelve Bristol Blenheims against KG 30's airfields at Aalborg, Denmark. One pilot turned back complaining of "fuel problems" and was court-martialled. His was the only bomber to return. The rest fell to anti-aircraft fire and fighters, and 24 airmen were killed and nine captured.

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• 7. Night Raids

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  As darkness fell at the close of Adlertag, Sperrle sent nine He 111s of Kampfgruppe 100 against the Spitfire factory at Castle Bromwich, Birmingham. The group was a specialist night strike unit with high expertise in night navigation. Even so, only four of the crews found the target. The eleven 551 lb bombs they dropped were too few to disrupt fighter production, and only around five fell inside the compound. Workers had gone to shelter, so casualties were small. Serious damage was done only to offices and a tool room, and a gas main was fractured.

  Hauptmann Friedrich Achenbrenner led another group of 15 He 111s from bases in Brittany across the Irish Sea to strike the Short Brothers factory on Queen's Island in Belfast, Northern Ireland. Five Short Stirling aircraft were destroyed there.

  KG 27 bombed Glasgow, although its specific target is unclear. Other bombers flew the length and breadth of Great Britain, hitting Bristol, Cardiff, Swansea, Liverpool, Sheffield, Norwich, Edinburgh and Aberdeen. Very little damage was done. Some rail tracks were cut temporarily, and around 100 casualties were suffered. It is unknown whether any German aircraft were lost. One German airman was found wandering the countryside at Balcombe, West Sussex, and no trace of his aircraft or the rest of the crew was ever found.

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• 8. The Scorecard

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  RAF Fighter Command claimed 78 German aircraft shot down on the 13th of August 1940, though another source puts the official claims at 64. Actual German losses were 47-48 aircraft destroyed and 39 severely damaged. The Luftwaffe claimed 70 Hurricanes and Spitfires and a further 18 Blenheim bombers destroyed in the air, an exaggeration of about 300 percent. It claimed another 84 RAF fighters on the ground. In reality the RAF lost 13 fighters and 11 bombers in the air, and 47 aircraft of various kinds on the ground. Overclaiming of this kind was common on both sides throughout the war.

  The failure of Adlertag did not stop the campaign. Attacks on RAF airfields continued through August and into September 1940, with heavy losses on both sides. Operation Sea Lion was postponed indefinitely. The Luftwaffe never developed a focused strategy for beating Fighter Command. It moved from bases to strategic bombing by day and night, then to aircraft factories, supporting industries and ports. It even tried attacking British morale.

  The Luftwaffe's high command, the OKL, believed the radar stations would actually help the German effort. In its view they would send RAF forces into large air battles for the Luftwaffe to destroy. The RAF's aircraft industry absorbed the losses, and pilots were replaced quickly enough to deny the Germans victory. Meanwhile, the serviceability rates and aircrew numbers of the Luftwaffe declined in August and September.

  Having failed to defeat the RAF, the Luftwaffe turned to the strategic bombing known as the Blitz. Its targets again varied widely, and no sustained pressure fell on any one kind of British target. Disputes among OKL staff centred on tactics rather than strategy. The air campaign over Britain in 1940 and 1941 ended in a decisive failure to end the war. As Hitler committed Germany to ever more military adventures, the Wehrmacht became overstretched and could not cope with a multi-front war. By 1944, the Allies were ready to launch Operation Overlord, the invasion of Western Europe. Britain remained the base from which that campaign could be launched, and a Western Allied presence stood ready to meet the Soviet Red Army in central Europe when the war ended in May 1945.

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