By 10 May 1940, when Germany invaded France and the Low Countries, 228 D.520s had been manufactured, but the French Air Force had accepted only 75, as most others had been sent back to the factory to be retrofitted to the new standard. As a result, only GC I/3 was fully equipped, having 36 aircraft. They met the Luftwaffe on 13 May, shooting down three Henschel Hs 126s and one Heinkel He 111 without loss.
More than 700 Potez 63.11 were delivered by June 1940, of which more than 220 were destroyed or abandoned, despite the addition of extra machine gun armament; the heaviest losses of any French type. The Potez 63.11 continued in service with the Vichy air force and with the Free French forces in North Africa seeing action with both. Production was resumed under German control and significant numbers appear to have been pressed into service by the Germans, mostly in liaison and training roles.
When the Germans overran the Low Countries and France in the spring of 1940, the Battle was thrown into the fight, with little result other than the slaughter of large numbers of RAF aircrew. In one of the most infamous incidents, on 12 May 1940 five Battles attacked bridges over Belgium’s Albert Canal in hopes of slowing down the German advance, with all five shot down.
The Potez 637 was one of the more modern aircraft in the reconnaissance groups, but losses were heavy. Production of this variant was limited, and the Potez 63.11 played just as important role in these group. The Potez 63.11 was also the most important aircraft in the army co-operation units, where it suffered heavy losses, mostly to ground fire and on the ground (although managed to hold its own against German fighters). By 1940 the entire family was outdated, with the lack of engine power.
In accounts of the German victory of 1940, the power of the Luftwaffe, together with the impotence of the Allied air forces, is given as one of the main reasons for the collapse. Neither of the other reasons has any factual basis. As the Battle of the Gembloux Gap illustrates, there was serious fighting in central Belgium, and the French clearly understood how to use armor, since the Cavalry Corps was temporarily victorious over no less than two German armored divisions.
But it has always been clear that German airpower was the key to their success. The Germans had a large and modern air force, while the Allies, a few British planes excepted, had a small and obsolete one. However, this idea has to be seriously qualified. The observation that the British and French air forces were not nearly as small or as old as was often claimed only compounds the mystery. Why was it that in May 1940 there was an almost universal cry by the Allied ground forces that the “skies were empty” of our aircraft?
In the account of the defense of the Netherlands, we noted the havoc wrought by the Dutch on the German transport fleet, pointing out that in large measure this was because the Dutch, alone of the countries attacked, had their air force and their air defense system on alert, so their few fighter planes were actually taking off at the moment of the German attack.
While German troops poured into Belgium across the intact bridges, the Luftwaffe attacked the bases of the Belgian air force. Unlike the Dutch, who had been on alert, the Belgians had counted on having some sort of notice, so the Germans caught many of their planes on the ground. Of the 160 planes operational and ready for combat on May 10, it appears that more than seventy were destroyed on the ground in the initial attack. But enough planes survived to enable the Belgian air force to mount 210 sorties over the next eighteen days of the battle. At the end of those eighteen days, seventeen planes had been shot down in aerial combat, and twenty-two were shot down by ground fire. The Belgians counted eighteen German planes shot down, and lost thirty-four men from their flight crews. That the Dutch and the Belgians were defeated does not mean that they simply gave up a fight against overwhelming odds.
Nor were the British and French idle. On May 10 the RAF lost thirty-four aircraft, only three of them destroyed on the ground by German bombers. The rest were shot down as they made bombing attacks on the advancing Germans, and an inspection of the locations and recorded causes—insofar as they are known—makes clear that many of these planes were in fact shot down trying to stop the advance through Luxembourg and the Belgian Ardennes, and that a surprising number of the losses came not from air-to-air attacks but from ground fire. On the next day, Saturday, the RAF lost twenty-three bombers—and this time, an appreciable number (eight) were lost to enemy bombing attacks—but the same pattern continued. On Sunday the RAF lost another thirty-four bombers, most of them again to ground fire as they tried to stop the German advance.
Given the number of tactical bombers available in France to the Allies, losses at this level—thirty aircraft a day—were intolerable. At this rate the Allied tactical bomber force would be wiped out in a few days, which is essentially what happened (the initial RAF deployment in France only amounted to some 400 aircraft, most of which were fighter planes). Nor did this happen because the Luftwaffe enjoyed command of the skies. British and French fighters were inflicting considerable damage on the Luftwaffe.
The problem was that neither the French nor the British air command had given any serious attention to the basic problems of tactical bombing. They both subscribed to the idea that level-flight bombing could destroy targets on the ground, and had neglected the impact of antiaircraft fire on such attacks, when, by definition, the bombers flying at low altitudes would be most vulnerable.
The Germans, for whom airpower was tactical, had taken care to provide their ground troops with the means of air defense. Göring, Hitler’s designated successor and commander of the Luftwaffe, had assumed control over everything military that was remotely connected with the air: Thus in the German system the air force had control both over airborne units and the air defense system. So the antiaircraft weapons mentioned earlier that accompanied German units into battle were manned by Luftwaffe personnel.
The German military, like most militaries, prepared for a war against the force it knew best—its own. As we have seen, the German air force was primarily tactical, and thus centered around ground attack. That was why the Germans had developed the dive-bomber—it was the only reasonably accurate system of bomb delivery. Tactical bombers were terribly vulnerable to enemy fighter planes, whether they were dive-bombers or level-flight bombers. To be successful in any shape or form, they needed to operate in skies cleared of enemy aircraft, which demanded air supremacy. Not unreasonably, therefore, when the Luftwaffe assumed the role of providing air defense for the army, it thought in terms of its own airpower doctrines.
Since these were tactical, it therefore developed a first-class ground to air system, built around a simple principle: The best way to shoot down tactical bombers was to saturate the air space they had to fly through to drop their bombs. Unlike the German army, which went to war rather badly equipped when it came to artillery and antitank guns, the flak units that accompanied them had three excellent weapons capable of a high volume of fire, and these weapons existed in huge numbers: about 6,700 rapid-firing special-purpose guns, one of 20 millimeters and the other of 37 millimeters, supplemented by 2,600 heavier weapons, mostly the famous 88-millimeter gun.
The Dutch and the Belgians were nearly as well equipped with antiaircraft guns, proportionally speaking, as the Germans. But the British and the French were sadly deficient in ground-to-air systems. The only truly automatic weapon available in quantity was the Hotchkiss 8-millimeter machine gun used by the French, a weapon totally inadequate for the purpose. Allied bombers were massacred when they tried to attack the advancing German ground forces, while the Luftwaffe was able to attack Allied ground forces almost at will.
The Allies had no real equivalent to the German Stuka, the JU 87 dive-bomber: Allied level-flight bombers were rarely able to hit anything they aimed at, while the JU 87 was a reasonably accurate delivery system. The Allied failure, then, was deeply entwined with airpower doctrines, and these had led the RAF, which in reality was the largest and most powerful air force in the world, down a series of blind alleys.
Thus the basic military reason for the Allied disaster had nothing to do with tanks or tank tactics; it was a function of the 586 Allied planes the two German flak units claimed to have shot down in the fighting. To leap ahead forty-eight hours in our narrative, and bring this matter to its logical conclusion: when, on Tuesday, May 14, the Allied high command saw the dangers of the German breakthrough above Sedan, they mounted intensive bombing raids. Bomber Command lost no less than forty-seven of its medium bombers on that one day in a futile attempt to stop the German advance. As one sympathetic and knowledgeable British aviation authority has noted, “It was one of the blackest days in RAF bomber operations.” In that one engagement Bomber Command lost more than half of the aircraft deployed.
When, in the succeeding days, the RAF bombing raids ceased, the reason was simple: The aircrews to mount those raids were either dead or were prisoners. Like the BEF of 1914, the Advanced Air Component of the RAF had simply been annihilated, losing 70 percent of its strength, with the French figures being almost precisely the same.
Most accounts of the air war in 1940 have focused on the fighter-to-fighter conflicts. In general both the French air force and the RAF Fighter Command gave a good accounting of themselves in these battles. Frequently the only Allied fighter planes mentioned are the British Spitfire and Hurricane, which formed the core of Fighter Command. Less well known are the exploits of their French counterparts. French squadrons equipped with the Curtiss 75A fighter shot down 33 German fighters and lost only three of their own; units equipped with the Morane-Saulnier 406 fighter plane shot down 31 German planes and suffered only six losses—this despite the fact that the MS 406 was thought to be obsolescent. Units equipped with the Bloch 152 shot down 156 German planes and lost 59. French pilots flying Dewoitine 520 fighter planes lost forty-four of their own and accounted for 175 Germans.
The surprisingly competent performance of the French and British (and Dutch and Belgian) fighter pilots has to a large extent obscured the massacre of their ground-attack craft, which has in turn led to a series of misconceptions, first about the air war itself, and second about the extent to which the Allies were “tricked” or “surprised” by “new” German tactics and technology. The one major cause of the defeat was clearly the Allied airpower failure—specifically the failure to have the right kinds of airplanes for tactical bombing, as well as a doctrine requiring the coordination with the ground forces. As with tanks, the Allies had plenty of planes, and in air-to-air combat, they clearly knew how to use them. Where they signally failed was in a fundamental misunderstanding of tactical airpower and the defenses against it.
There was one other weakness on the Allied side, which is usually passed over and goes a long way toward explaining why the ground forces felt so overwhelmed by German aircraft. German airfields were only half an hour’s flying time from their initial targets. The short distances allowed the Luftwaffe to take advantage of a unique feature of the air war. It was customary, for obvious reasons, to register the strengths of opposing armies by counting men, guns, and vehicles. One armored division deployed into battle had the strength of one armored division. It could only be deployed once. But aircraft could fly over the target, drop their bombs, return to base, refuel and re-arm, and launch another mission, which is why nowadays one speaks not of aircraft but of sorties, one aircraft flying one mission.
In strategic bombing this distinction hardly came into play. It would take a bomber hours (and, given the speed of the bombers of 1939 and the distances to targets, many hours) to get to its target and hours to return. The result, given the maintenance needs of both aircraft and flight crew, was a leisurely tempo of operations. But if the aircraft were immediately adjacent to the battlefield, one plane could fly three, four, five sorties a day, and particularly in May, when it was light nearly fifteen hours or more.
Since the Germans flew many more sorties per day than their opponents did, this had the practical effect of multiplying the size of their air force. If one air force deploys five hundred planes and each plane flies two sorties a day, and the other air force deploys the same number of planes, but each plane flies four sorties a day, then to all intents and purposes, the first air force is outnumbered two to one in the air.
In the case of May 1940, the imbalance was much worse than that. The RAF, although it was averaging about two sorties per plane per day, was still thinking strategically, not tactically. Airfields in France were located far behind the frontier, so the planes were protected from enemy attack. But that meant it took the planes longer to get over the battlefield, so the logistics of the situation virtually guaranteed that the RAF would operate less efficiently in the air than its opponents.
To say that no one had pondered this is an understatement. Once the fighting started, the RAF actually deployed more of its airpower than did the French, twelve of its forty operational fighter squadrons, while the French air force only committed 580 of its 2,200 fighter aircraft to the battle—so the British commitment was proportionally greater than the French (a fact that would lead to a certain justifiable bitterness on the part of the RAF and the British).
But in order to compensate for the greater number of sorties being flown by the Luftwaffe, the RAF would have been forced to commit all of its fighter strength, and the French would have had to have at least doubled their commitment, simply because the Germans were able to mount more combat missions with fewer aircraft than their opponents. And since they deployed as many aircraft as the Allies, the net effect was one of overwhelming superiority in the air. This accounts for the perceived initial advantage of the Germans over the Allies. By mounting more sorties per plane initially, the Germans had a great advantage, but had the war continued, the advantage would have turned to the Allies; first because the wear and tear on their planes was substantially less (as they flew less), and second because the Allies had committed a significantly smaller portion of their aircraft to the fight.