Battle of Britain

• 1. Introduction

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  The Battle of Britain earned its name before a single aircraft took to the skies in its defense. On the 18th of June 1940, Winston Churchill stood before the House of Commons and declared: "What General Weygand called the 'Battle of France' is over. I expect that the Battle of Britain is about to begin." He spoke those words more than three weeks before the battle's official start date. At the time, France had already fallen, British and French soldiers had been pulled off the beaches at Dunkirk, and Germany's military machine had overwhelmed the Low Countries and most of Western Europe in a matter of weeks. Britain stood alone.

  What followed was unlike any military campaign that had come before it. For the first time in the history of warfare, a major campaign would be decided entirely in the air. On one side was the Luftwaffe, the most combat-experienced air force in the world, fresh from victories across Europe. On the other was the Royal Air Force and the Fleet Air Arm, defending an island whose loss, Churchill warned, would send "the whole world, including the United States, including all that we have known and cared for" into "the abyss of a new Dark Age."

  The British officially date the battle from the 10th of July to the 31st of October 1940. The Germans, who include the sustained night bombing known as the Blitz in their accounting, regard it as lasting from July 1940 to May 1941. Either way, what happened over the skies of Britain that summer and autumn determined whether Nazi Germany would win the war outright. This is the story of how that battle was fought, who fought it, and why the outcome was not as certain as either side believed.

• 2. Seeds of Air War

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  Strategic bombing as a weapon against civilian populations first appeared during the First World War, and by 1918 it had already reshaped British military thinking enough to merge the army and navy air services into a single Royal Air Force. The RAF's first Chief of the Air Staff, Hugh Trenchard, shared a conviction with strategists like the Italian theorist Giulio Douhet: that air power had made the bloody stalemate of trench warfare obsolete. Their doctrine was almost fatalistic. "The bomber will always get through," went the slogan, and the only answer was to build a deterrent force capable of matching the enemy's retaliation. Fighter interception, they believed, was nearly impossible, because fighter planes were no faster than the bombers they might chase.

  Germany, for its part, was forbidden a military air force by the 1919 Treaty of Versailles. What the Germans could not do openly, they did quietly. Civilian airlines like Deutsche Luft Hansa developed aircraft such as the Junkers Ju 52, which could carry passengers but was easily adapted into a bomber. In 1926, a secret fighter-pilot school at Lipetsk began training German airmen in the Soviet Union. By 1933, when the Nazis came to power, the groundwork had been laid for rapid rearmament. On the 1st of March 1935, the Luftwaffe was formally announced, with Walther Wever as its first Chief of Staff.

  Luftwaffe doctrine from that same year placed air power squarely within broader military strategy. Air superiority and battlefield support for ground and naval forces were the primary tasks. Strategic bombing of industries and transport was a longer-term option, dependent on the state of the war. What the 1935 doctrine explicitly excluded was bombing civilians to destroy homes or undermine morale: the Luftwaffe considered this a waste of strategic effort. That principle would bend badly under the pressures of 1940.

  The Spanish Civil War from 1936 to 1939 gave Luftwaffe pilots real combat experience. The Condor Legion tested aircraft and tactics against live opponents. Wolfram von Richthofen became a champion of close air support for ground forces. The difficulty of hitting targets accurately pushed Ernst Udet to require that all new German bombers be capable of dive-bombing. Long-range four-engined strategic bombers were cancelled. These choices would limit German reach when the fight for Britain came.

• 3. Germany's Aims

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  Adolf Hitler's attitude toward Britain was, by his own account, one of admiration rather than enmity. His 1925 book Mein Kampf described Britain as a potential ally against communism. In 1935, Hermann Göring welcomed British rearmament as a sign that a future partner was strengthening itself. Throughout the period of the battle, Hitler repeatedly sought a negotiated peace rather than a fight to the finish.

  Britain's Foreign Secretary, Lord Halifax, was open to exactly that. In May 1940, as France collapsed, Halifax secretly asked a Swedish businessman to open contact with Göring about negotiations. During the War Cabinet Crisis of that same month, Halifax argued for bringing in the Italians as intermediaries. Churchill rejected this with majority Cabinet support. An approach through the Swedish ambassador on the 22nd of June was reported to Hitler, and throughout July his government made wider attempts to find a diplomatic exit. On the 19th of July, Hitler addressed the German Parliament in Berlin, appealing to "reason and common sense" and claiming he could "see no reason why this war should go on." The British government received the speech as an ultimatum and rejected it.

  Halifax continued seeking peace until Churchill sent him to Washington as ambassador in December 1940. As late as January 1941, Hitler expressed continued interest in negotiations. The puzzle of a war neither side fully wanted against each other is one of the battle's stranger threads.

  Yet the military machine had its own momentum. On the 16th of July 1940, Hitler's Directive No. 16 ordered preparations for Operation Sea Lion, an amphibious and airborne invasion of Britain, to be ready by mid-August. The German Navy's commander-in-chief, Grand Admiral Erich Raeder, consistently stressed the operation's impracticality given the strength of the Royal Navy in the English Channel. A 1939 German naval study had already concluded that air superiority alone would not be enough: naval superiority was also required. The Luftwaffe's own assessment was that invasion could only be "the final act in an already victorious war." Hitler held a meeting on the 31st of July at which the navy said the 22nd of September was the earliest possible invasion date, but Hitler preferred September. He told his army chiefs he would decide on launching the landing operation eight to fourteen days after the air attack began.

• 4. The Aircraft and Their Limits

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  Messerschmitt's Bf 109E was the Luftwaffe's premier fighter, and it had genuine advantages over its British opponents. It climbed faster and flew up to 40 mph faster in level flight than a Hurricane Mk I equipped with a constant-speed propeller; the gap was even larger against the original version of the Hurricane. Its DB 601 engine used fuel injection rather than a carburettor, which meant the 109 could push into a negative-gravity dive without the engine cutting out. RAF fighters, by contrast, would stall when their pilots tried the same manoeuvre. This single mechanical difference gave German pilots an escape route that British pilots could not easily follow.

  The RAF found answers. By mid-1940 all Spitfire and Hurricane squadrons had converted to 100-octane aviation fuel, which unlocked an Emergency Boost Override giving their Merlin engines roughly 30 mph more speed at low altitudes. In September 1940, the more powerful Hurricane Mk IIa entered service in small numbers, capable of 342 mph. It was still 15 to 20 mph slower than a Bf 109 at comparable altitudes, but the gap had narrowed.

  Armament told a similar story of trade-offs. British fighters carried eight Browning .303-calibre machine guns firing bullets. Most Bf 109Es had two 20mm cannons firing explosive shells, supplemented by two 7.92mm machine guns. The cannons were far more destructive: it was not unheard of during the battle for German bombers to limp back to France with as many as two hundred .303 bullet holes and still fly. One factor alone balanced the scales. As Alfred Price wrote in The Spitfire Story, the differences between the Spitfire and the Me 109 in performance and handling were only marginal, and in combat they were almost always surmounted by tactical considerations of which side had seen the other first, which had the advantage of sun, altitude, numbers, pilot ability, and the amount of fuel remaining.

  Fuel remaining was the Bf 109's most punishing constraint. Without long-range drop tanks, usually of 300-litre capacity, and these were only introduced in limited numbers late in the battle, the 109E had a range of 600 km and an endurance of just over an hour. Once over Britain, pilots watched for a red "low fuel" light on the instrument panel. When it came on, they had to turn back for France immediately, regardless of what was happening around them. German pilots coined a term for the dread this produced: Kanalkrankheit, or Channel sickness. The twin-engined Bf 110 Zerstorer had been designed as a long-range escort to compensate, but it proved too unmaneuverable against single-engined RAF fighters. On the 13th and the 15th of August, the Bf 110 lost thirteen and thirty aircraft on those two days alone, the equivalent of an entire Gruppe.

• 5. The Pilots Who Flew

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  On the 1st of July 1940, RAF Fighter Command could muster some 1,103 fighter pilots. The Luftwaffe, by contrast, had 1,450 experienced fighter pilots available, many of them Spanish Civil War veterans with comprehensive training in aerial gunnery and fighter-versus-fighter tactics. German training manuals explicitly discouraged heroism, stressing the importance of attacking only when the odds favoured the attacker.

  The RAF's pilot pool had been thinned by the fighting before the battle even began. The Battle of France alone had cost 435 pilots permanently, with many more wounded, and others had been lost in Norway. Although Fighter Command was never short of aircraft, it became dangerously short of experienced men to fly them. With aircraft production running at 300 planes a week, only 200 pilots were being trained in the same period. Replacement pilots, often with minimal flying time and sometimes no gunnery training at all, suffered high casualty rates from the moment they arrived at front-line squadrons.

  What the RAF lacked in German-style depth, it made up for in breadth. About 20 percent of the pilots who flew in the battle were not British. The RAF's roll of honour for the period from the 10th of July to the 31st of October 1940 lists 595 non-British pilots who flew at least one authorised operational sortie. Among them were 145 Poles, 127 New Zealanders, 112 Canadians, 88 Czechoslovaks, 32 Australians, 28 Belgians, 25 South Africans, 13 French, 10 Irish, and 9 Americans, along with individuals from Jamaica, Barbados and Newfoundland. Many of these men had already watched their own countries fall to German occupation and flew with a particular intensity.

  The No. 303 Polish Fighter Squadron became the highest-scoring fighter squadron of the entire battle, despite joining the fighting two months after it had begun. Air Chief Marshal Hugh Dowding, the commander of Fighter Command, wrote afterward: "Had it not been for the magnificent material contributed by the Polish squadrons and their unsurpassed gallantry, I hesitate to say that the outcome of the Battle would have been the same." The names of the Allied and Commonwealth airmen who died are inscribed in a memorial book that rests in the Battle of Britain Chapel in Westminster Abbey, beside a stained glass window bearing the badges of the fighter squadrons and the flags of the nations that sent men to fight.

• 6. The Dowding System

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  Before the battle, an average interception mission by RAF fighters had roughly a 30 percent chance of the pilots ever seeing their target. By the time the Battle of Britain was being fought in earnest, the system that Air Chief Marshal Hugh Dowding had built raised that average above 75 percent, with some periods reaching 100 percent: every fighter dispatched found and intercepted its target.

  The solution was what became known as the Dowding system, named for its architect, nicknamed "Stuffy" Dowding. Reports from the Chain Home radar network and the Observer Corps fed into Fighter Command Headquarters at Bentley Priory, where they were filtered to combine multiple sightings of the same formation into a single track. That information moved by telephone to Group headquarters, where controllers re-created the picture on a map table. Sector commanders then selected squadrons and directed them toward specific intercepts, while simultaneously controlling the anti-aircraft batteries in their areas through an army officer sitting at each fighter controller's side.

  The Luftwaffe, by contrast, had to operate largely blind. German intelligence was fractured and riven by internal rivalry; its performance was described as "amateurish." In July and August 1939, the airship Graf Zeppelin had flown around the British coast packed with listening equipment, attempting to pick up RAF radio and radar transmissions. The Luftwaffe correctly identified that ground controllers were directing RAF fighters, but incorrectly assessed the system as rigid and ineffective. They never understood that it was the opposite.

  The result was a form of what is now called force multiplication. RAF fighters, guided to within striking range before they could be seen, were effectively as capable as two or more Luftwaffe fighters operating without that advantage. The Luftwaffe consistently believed it was attriting Fighter Command at three times the actual rate. Multiple times during the battle, German commanders concluded that Fighter Command was on the verge of collapse, only to find that the RAF could still put up defensive formations at will. To cover for the secrecy surrounding Enigma decrypts that contributed to this picture, Dowding created a dedicated reconnaissance unit, No. 421 Flight RAF, equipped with Hurricanes and Spitfires, whose visible patrols gave a plausible cover story for how the RAF seemed always to know where German formations were heading.

• 7. Shifting Targets, Final Outcome

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  German strategy during the battle never settled. On the 1st of August, Hitler's Directive No. 17 ordered the Luftwaffe's Adlertag campaign to begin around the 5th of August, subject to weather, aiming to destroy RAF Fighter Command in southern England within four days. The three Luftflotten positioned against Britain divided the country between them: Luftflotte 2 under Albert Kesselring struck south-east England and London, Luftflotte 3 under Hugo Sperrle hit the West Country, Wales, the Midlands and the north-west, and Luftflotte 5 under Hans-Jürgen Stumpff attacked the north of England and Scotland from bases in Norway.

  Kesselring and Sperrle disagreed about objectives. Sperrle wanted to systematically destroy the radar and airfield network that made the Dowding system work. Kesselring favoured a direct assault on London, either to batter the government into submission or to draw RAF fighters into a decisive battle of annihilation. Hermann Göring, the Luftwaffe's commander-in-chief, provided no resolution to this dispute and issued only vague directives during the opening stages. The campaign shifted targets repeatedly: coastal shipping convoys first, then ports, then RAF airfields and infrastructure, then aircraft factories, then London itself.

  The shift to London came on the 4th of September 1940, when Hitler authorised major day and night attacks on the capital, the campaign that became known as the Blitz. RAF Bomber Command had already struck back: night raids on German invasion ports disrupted the conversion of barges needed for Operation Sea Lion. On the 16th of September, Göring ordered the transition to the first independent strategic bombing campaign, focused on night operations against infrastructure and food stocks. The Luftwaffe had proved unable to sustain daylight raids against a Fighter Command that refused to be destroyed.

  Germany's failure to eliminate British air defences was the first major German defeat of the Second World War. Operation Sea Lion was postponed and eventually cancelled. The aerial assault that followed, the sustained night bombing of British cities, caused immense civilian suffering, but it did not force the negotiated peace Hitler had sought. Among those who died between the 10th of July and the 31st of October 1940 were 1,495 RAF aircrew in total: 449 fighter pilots, 718 from Bomber Command, and 280 from Coastal Command. Forty-seven New Zealanders lost their lives, including 15 fighter pilots. Their sacrifice, alongside that of the Polish, Czech, Canadian, Australian, South African, Belgian, French and Irish airmen who flew with them, had kept Britain in the war.