With only limited knowledge of Luftwaffe strengths and production statistics, the Air Ministry’s Air Intelligence Branch entered World War II at a significant disadvantage, and with a minimal understanding of the enemy’s order-of-battle that anyway would change dramatically with the occupation of France, Belgium, and the Netherlands. Conversely, the Luftwaffe’s grasp of the Royal Air Force (RAF) was considerable, partly because of the very public debate in Great Britain on the subject of relative fighter and bomber squadrons, but also because of the espionage of Dr. Herman Goertz in 1938, who had visited and sketched numerous RAF airfields in southern and eastern England. Nevertheless, the German Air Ministry never fully appreciated the scale of RAF losses in France in 1940, amounting to 944 aircraft, including 450 fighters, leaving Fighter Command with only 502 planes with which to defend the country from the long-dreaded assault on London from the air, an offensive that had been anticipated since the aerial bombardment of Madrid, Guernica, and Barcelona.
The shortcomings of British details of the Luftwaffe would be rectified during 1940 by aircrew interrogations and, latterly, signals sources including Enigma intercepts and radio direction-finding. Thereafter, technical intelligence became predominant, with German and British scientists making research breakthroughs at an astonishing pace in an effort to gain an edge over the enemy. Both sides pursued proximity fuses, atomic weapons, jet engines, guided bombs, pilotless aircraft, rockets, radar, and electronic countermeasures, and some of the German projects were to be disclosed to the Secret Intelligence Service in the Oslo Report.
In strategic terms, the confrontation between the Luftwaffe and the RAF during the summer of 1940, which came to be known as the Battle of Britain, proved crucial, as Adolf Hitler’s plan for an invasion depended on establishing air superiority. However, handicapped by obsolescent Heinkel 111 bombers and the poorly performing but more modern Junkers 88, the Luftwaffe’s tactic of concentrating on the destruction of the RAF on the ground and in the air was canceled at the end of August, just when it was achieving its objective. Hitler’s intervention, and his insistence on transferring the attacks to London, enabled the RAF to regroup just as it was on the point of collapse. Poor Luftwaffe intelligence resulted in the High Command’s failure to grasp how successful the Messerschmitt-109s had been. On 13 August, the German offensive began in earnest with 702 single-engined fighters, 227 twin-engined Me-110s, 875 serviceable bombers, and 316 dive bombers, ranged against 749 Hurricanes and Spitfires, a strength improved by the introduction of 490 aircraft built during July. The Luftwaffe lost 45 planes, compared to 13 RAF fighters, and six of the RAF pilots survived to fly again. On the next day, the Luftwaffe had 19 aircraft shot down to the RAF’s eight. On 15 August, the Luftwaffe lost 75 planes to the RAF’s 34, and on 16 August the results were much the same, with 45 German aircraft destroyed for only 21 RAF fighters. On 18 August, 71 intruders were shot down for 27 defenders, but the Luftwaffe aircrews had greatly exaggerated their claimed successes so German air intelligence estimated the RAF was down to its last hundred planes, whereas on 23 August, having been replenished, it actually had 700 serviceable fighters. During August, the RAF had lost 359 aircraft for 653 enemy planes, and the shortage was not in fighters, but qualified pilots, whose numbers were running dangerously low. However, the real turning point was an accidental German attack on London on 25 August for which a reprisal air raid on Berlin was launched. Infuriated, Hitler ordered London to be flattened, and on 7 September a force of 300 bombers, with 600 escorts headed toward the Thames and were met by 23 RAF squadrons. Forty German planes were shot down, compared to 28 RAF fighters. These statistics mystified the Luftwaffe analysts, who on 8 September had calculated the RAF’s fighter strength at 465, of which only 345 were likely to be serviceable, but since then German pilots had claimed 288 kills, thereby theoretically leaving the RAF with only 177 planes.
On Sunday, 15 September, 300 RAF fighters flew against the largest raid ever and shot down 60 intruders for the loss of 26 defenders (even though the BBC claimed 185 raiders were shot down); this final conflict persuaded Hitler that the air supremacy required for a successful cross-Channel invasion had not been accomplished, so he ordered an indefinite postponement of Operation SEELÖWE. Early in October, with the weather deteriorating, the Luftwaffe abandoned all further daylight missions over England, and the attempt to eliminate RAF Fighter Command was over. From 10 July until the end of October, the Luftwaffe lost 1,773 aircraft, compared to the RAF’s 915, and there was not a single week during that period that the raiders inflicted greater losses on the RAF.