The quality of the aircraft designs is of more importance than totals. There were four types of bombers in use by the German Air Fleets in the summer of 1940, and it must be emphasized that the descriptions that follow refer to these alone, and not necessarily to subsequent models of the same aircraft.

The oldest type still in operational use in 1940 was the Dornier Do 17, the ‘Flying Pencil’, which still equipped about a quarter of the bomber and reconnaissance units facing Britain. During the Battle production ceased and the type was being phased out.

In 1934, when this design was on the drawing board, civil airlines still cherished the idea that there was big money to be made from air mail. But those hopes, and the cramped Dornier prototype, were put into storage as times changed and airlines counted their success in passenger miles. Resurrected by the Luftwaffe, the Do 17 enjoyed a brief moment of glory at the Zurich Air Show in 1937, when it was equipped with Daimler-Benz DBA motors and proved faster than any fighter anywhere in squadron service.

But Willy Messerschmitt won the battle for Daimler-Benz engines (to put in his Bf 109s), and the ‘Schnellbom-bef’ had to make do with whatever power-plants Dornier could get. And while the Dornier's speed decreased, fast monoplane fighters came into service. In an effort to put new life into his ‘Pencil’, Dornier called his export Do 17Z a Do 215, and later variants (some of which got the coveted DB 601 engines) were expressly designed for reconnaissance duties. For photographic flights, its very small payload did not matter. In spite of its comparatively low speed and a complete absence of protective armour, it was popular with crews, who considered it strong and reliable, and stable in flight.

This was the most numerous of the Air Fleet's bombers. It was a robust airframe that readily adapted to considerable modification. Since the Spanish Civil War it had been given a whole new glazed nose section. It could carry almost double the bomb-load of the Do 17. But Heinkel, too, had sacrificed his Daimler-Benz engines to Willy Messerschmitt. The He 111P (with DBA engines like the Bf 109E) had now been followed by the He 111H, with Jumo 211A engines. It was now the slowest of the twin-engined bombers, even slower than the Do 17. To sweeten the pill for the crews assigned to them, the new Heinkels were being given a great deal of protective armour (up to 600 lbs of it) and extra machine guns. But the He 111 proved inadequate against a determined defence and although it continued in use on other fronts, Heinkels in the west were relegated first to night bombing (by mid-September 1940), and then to anti-shipping and transport work.

Not only the best bomber in service with the Luftwaffe, this was probably the best one in service anywhere at the time (entirely comparable with the later RAF Mosquito). It was produced at an astounding speed, going from drawing board to first flight in the single year of 1936.

Too late for the Spanish Civil War, it had service trials in the spring of 1939. Although its bomb-load was much less than that of the He 111, the Junkers bomber was much faster, and unit war diaries of 1940 showed that men of the German bomber force had a better chance to fight and survive in this bomber than in any other.

The decision to add a dive-bomber requirement to the Junkers Ju 88's role brought problems of over-stressed airframes. Crews were given cautionary instructions about aerobatics, and this gave rise to rumours and doubts about the bomber's airworthiness. This situation was not improved by the high casualties that bomber fleets suffered in 1940, and was compounded by Feldmarschall Milch, who, motivated by spite and ambition, conducted a campaign against the Junkers Ju 88. It was a campaign from which this fine Junkers aircraft never completely recovered.

Developed from an early Junkers design after Udet saw a demonstration by Curtiss Helldivers, the Ju 87 was in a quite different category from the medium bombers of the Kampfgeschwader. This single-engined machine, with its massive cranked wings, spatted undercarriage, and screaming sirens, had earned sole title to the generic word 'Stuka' (dive bomber).

For the Luftwaffe High Command the Ju 87 seemed to provide precision bombing in a way that was very cheap in money, materials, and manpower. Delicately balanced, a delight to fly, it was one of the most specialized designs ever to go into large-scale production. There was a window in the floor so that the pilot could spot the target, and there were lines inscribed on the canopy to gauge the angle of dive. An automatic trim change was connected to the dive-brakes. These air-brakes made the dive vertical if the pilot was experienced — very slow, so that his aiming could be done with great care. But the Junkers Ju 87B — the type used in 1940—could carry only a 1000-lb bomb or one 550-lb and four 110-lb bombs, while the Do 17 carried 2,200 lbs and the He 111 4,400 lbs, in any configuration of types and sizes. The Ju 87B's range limited it to targets well within 200 miles of its base, which meant the English coastal region. And the very poor aerodynamic shape of the aircraft meant there was little chance of improving the bomb-load or of adding armour. Even during the fighting in Poland, the 'Bertha' had suffered severe casualties in the face of small-arms and anti-aircraft guns. So at the time of the Battle of Britain the far better Ju 87D was on the drawing board. Meanwhile the Stuka crews had to manage with the Bertha, which with a top speed of 232 mph was the slowest operational aircraft used by either side.

The Ju 87R (Reichweite: range) was no better than the B version except in having long-range fuel tanks. These aircraft were flying in early 1940. The first deliveries went to the highly skilled I/StG 1.

The Stuka units were still getting a great deal of publicity from the propaganda machine. For a keen young pilot there was more prestige in a posting to a Stuka unit (or to a Messerschmitt Bf 110 unit) than in being chosen for single-engine fighters.

The Luftwaffe's fighter force consisted of two types of fighters. The only single-seat fighter in service was the Messerschmitt Bf 109. Its range was limited. From the most northerly of France's airfields it could get only as far as London and back.

However, the Luftwaffe had faced up to the problem of fighter protection for bomber fleets in a way that no other air force had done. It had provided long-range fighters for the escort role. These twin-engined Messerschmitt Bf 110s had been given the excellent DBA engines, and the pick of the Luftwaffe's fighter pilots had been taken from Bf 109 units. It was part of a plan to establish Göring's Zerstorer (destroyer wings) as elite units.

The Bf 110 was a much maligned aircraft and has often been written off by historians as a negligible factor in the 1940 battles. It was worth giving it respectful attention. Built into the nose of the Bf 110 there was a battery of four 7.92-mm MG 17 machine guns and two 20-mm MG FF cannons. There was also a rear-facing machine gun for the second crewman.

It is easy, with the advantage of hindsight, to scorn the Luftwaffe's Zerstorer theories. But the Luftwaffe kept the Bf 110 in production until the last days of the war, providing it all that time with the same high-performance engines that were needed by the single-seat fighters. And the role of any fighter is two-fold: the Bf 110 was not able to tackle enemy fighters on equal terms but it was effective, later in the war, used against bombers. On the eastern front and against the USAAF Fortresses in daylight, and with airborne radar in the night-fighter role, the 'Ironside' earned its keep. It was about the cheapest twin-engined operational machine used by the Germans.