From 10 May until 11 June, the British and French air forces lost around 1,850 aircraft in combat, of which some 950 were French. Luftwaffe losses were around 1,100. These figures suggest a clear victory for the Luftwaffe, but even they give no idea of the scale of the defeat suffered by the Allied air forces. Such heavy losses, indeed even heavier losses, would have been perfectly acceptable if they had enabled the Allied armies to avoid such a total and catastrophic rout.
Most French problems stemmed from the way long-range bombing dominated French thinking at all levels, political and military. The threat the bomber posed to French cities was overestimated and what it might achieve on the battlefield underestimated. Paranoia over the long-range bomber had emerged long before the outbreak of the First World War. In 1914–1918, the needs of the front prevented this from dominating military thinking, but in peacetime, the theory and the fear were able to flourish. French politicians assumed bombing could bring swift and total defeat and ruin to their country.
The idea that bombers alone would decide future wars was a far more radical notion than the blitzkrieg that would eventually defeat France. The German strategy was just a restatement of the importance of mobility, with the internal combustion engine replacing the horse. Douhetism envisaged an entirely new form of warfare in which armies would be irrelevant. It is perhaps no coincidence that these theories took root most strongly in the democracies (France, Britain, and the United States) where public anxiety over aerial bombardment could find an effective political voice. In the totalitarian states (Germany, USSR, Italy, and Japan), where public opinion had less influence, more pragmatic military uses of air power prevailed.
The French are often accused of trying to fight the Second World War with the weapons and ideas of the First World War. This is true for some aspects of policy, but as far as the air war is concerned, in 1940, France needed the sort of Air Force it had in 1918. The Great War had underlined the value of aerial reconnaissance and the need for the strongest possible fighter force to enable the reconnaissance fleet to operate. The Air Division had demonstrated how effective air power could be as a flexible defensive and offensive weapon. In 1940, the French did not have enough fighters, they had no equivalent of the Air Division and were completely taken by surprise when the Luftwaffe turned their very similar VIII Air Corps on the French Army. Instead of building on the close air support tactics developed in the First World War, the French focused on developing a long-range deterrent bomber force. How fast, how far, and how many tons bombers could carry became the yardstick for measuring French air strength. Ironically, once the country was at war, it was the Ju 87, the slowest German bomber with the least range and lowest bomb load, that proved so decisive.
The French Army never believed the long-range bomber could be decisive; they had no doubts that wars would still be won or lost on the battlefield. Unfortunately, the zeal with which the Douhet-style conflict was promoted induced a scepticism within the Army about all forms of bombing, strategic and tactical. Battlefield bombing in direct support of ground forces proved to be far more effective than the generals imagined, and, more importantly, meant armies did not have to wait for artillery. The French found themselves facing a German Army that could advance far more rapidly than they believed possible. This was at least as significant as the actual damage bombing inflicted.
Yet developing a long-range bomber force was not a mistake. It might not decide the outcome of a war, but it did have huge influence in peacetime. Politicians needed the security a powerful bomber fleet provided. Bargaining positions were determined by how many bombers you had. Foreign policy was shaped by the bomber. The value of a powerful bomber fleet was amply demonstrated during the Rhineland and Sudetenland crises. Hitler got his way without firing a bullet. At the time, it did not occur to the Air Force or the politicians that the long-range bomber was not a decisive war winning weapon, that its value was political and psychological rather than military. Without fully understanding what was happening, it was difficult to see that a balance was required between what the politicians needed in peacetime and the military needed for fighting a war. Attempts to match the German bomber fleet led to far too much effort being devoted to strategic bombers at the expense of shorter-range tactical bombers. It was the latter that France would need when it came to war. They also happened to be much easier to build. The LeO 451 was not only the least effective and suffered the highest loss rate of any French bomber, but it also required far more resources to build.
The lack of trust between Army and Air Force was another major problem. Even in the tactical domain, the Army felt that in the First World War, the Air Force had tended to disregard Army needs and go its own way. The Air Force focus on independent strategic air warfare in the interwar years increased the mistrust. The more independent the Air Force became, the less the Army trusted it. The Army had good reason not to trust their sister service. Even in the May–June campaign, d’Astier tended to run air operations as he thought best, rather than as the Army wanted.
As far as the Army was concerned, centralised control meant Air Force control, and the only way the generals felt they could be sure of getting the air support they needed was to attach squadrons permanently to army units, even though this made it even more difficult to focus air effort where it was needed. Ironically, as the Army did not think tactical bombing was so important, control of the bomber force was centralised, and it could be switched to where it was required. Fighter squadrons, however, were attached to armies, which stretched available resources along the length of the front. Fears that French cities and industry would be wiped out by German bombing meant fighters also had to defend these targets. In the end, French fighter resources were stretched in two directions: along the front and deep into the French rear. Even if the French fighter force had matched the Luftwaffe in terms of quality in 1940, it would have still been at a disadvantage numerically because of the way it was dispersed.
The inability to secure local air superiority meant that the large fleet of reconnaissance planes the French had assembled, and into which so many resources had been poured, could not function. The French were quite right to emphasise the importance of reconnaissance, but a smaller reconnaissance fleet with a larger fighter force to protect it, would have enabled the French to gather more information.
On the technical side, the French fascination with large multi-seater, multi-purpose planes proved particularly unfortunate. France missed out completely on the Blenheim and Dornier Do 17 generation of bomber design and as a result, the French bomber force had nothing suitable to fly by day when war broke out. Even in the 1940 campaign, the products of the multiplace de combat era flew nearly as many sorties as the French bombers that were supposed to replace them. Perhaps more significantly, the low speeds expected of the turret laden bombers, meant required fighter speeds were too low, and although the BCR multi-purpose plane was abandoned in 1934, French fighter design never quite caught up with what was being achieved elsewhere.
France started rearming much later than Germany, but it was not fatally late. The mistake was the planes the French decided to build. The RAF and Luftwaffe fought the air battles of 1940 largely with planes conceived in the early thirties or upgrades of these designs. For France, this was the Amiot 340, M.S.406, Potez 63, and Mureaux 113 generation. France, however, decided these were not good enough and placed all their trust in the next generation. This was not necessary. The makeshift Potez 633 was a reasonable equivalent to bombers like the Dornier 17. The Mureaux 117 was no more obsolete than the Henschel Hs 126 the Luftwaffe used successfully. An upgraded M.S.406 could not have matched the Bf 109, but it might have been good enough. These were the only planes that France could have built in sufficient numbers in time for the 1940 campaign.
In peacetime, there was a case for waiting for the very latest designs, but once war broke out, continuing to rely on the 1936 generation became a fatal mistake. The Dewoitine D.520 and Bloch MB.174 were excellent planes that would have played an increasingly important role from mid-1940 onwards. The Martin 167 and Douglas DB-7 did go on to have very successful careers with the RAF. They were all capable of making some contribution in the spring of 1940, but it was too soon to be relying on them. New planes invariably have teething problems and aircrews need time to become familiar with them. In the end, the Dewoitine D.520 was no more successful than the Curtiss H75, because the H75 pilots had learned how to get the best out of their fighters. Fighter production plummeted when the M.S.406 was phased out. The Potez 633 was easy to build and could have been built in large numbers. In the end, France fell between two stools: it did not have enough combat planes of either the old or the new generation.
Even with the resources that were available in 1940, the French could have done better. No battle is lost before a shot is fired. On the ground, there were opportunities for the French to rescue the situation even after the breakthrough at Sedan. Once it was obvious how serious the situation was, there was plenty of urgency, but little flair or improvisation. During the 1918 crises, doctrine had been ditched and instinct took over. Fighters and reconnaissance planes, as well as bombers, were thrown into the ground-attack role, regardless of doctrine. In 1940, everything was done by the book. Tremendous risks were taken by committing large ungainly multi-seaters and floatplane bombers to daylight operations. Frantic efforts were made to make obsolete long-range bombers available for operations, but there was no thought about how smaller, more manoeuvrable fighters or reconnaissance planes might be used for ground-attack. A striking feature of the campaign was how obsolete biplanes like the Henschel Hs 123 and Fokker C.V could be used for ground-attack, provided they were not expected to attack targets far beyond the front line. The way French aircraft were used was determined by what they were designed to do rather than what they might be capable of doing. The French had far more useable planes than they imagined but the lure of the ultra-modern that had led them to reject the 1934 generation of combat planes also blinded the French to how even older equipment might make a contribution.
The strange contrast between frenzy and inaction was another striking feature of the French reaction to the crisis. Rear defence flights were formed and squadrons converted to new equipment in days, but elsewhere, trained foreign and French aircrews were left kicking their heels with nothing to fly. Army and Air Force commanders called for maximum effort, but at the height of the battle, some units remained unused and with those that did operate, sortie rates throughout the campaign were low by comparison with other Allied and enemy air forces. D’Astier placed too much emphasis on using his squadrons in a controlled, measured way, but in some ways, it was too measured. He insisted that available planes had to be used correctly, when the crisis facing the French demanded a more radical approach. The way any combat planes are used has to depend on the situation and how what is available can make a contribution rather than peacetime practice, doctrine and theories about how planes ought to be used.
Much is often made of various quotes which seem to prove that French Army generals did not understand the importance of air power. Although they underestimated the value of close air support, they never doubted the need for a powerful air force. The Army’s fierce fight to retain control of the Air Force is proof of that. Many of the quotes were provoked by frustration at the constant talk of bombers deciding wars on their own. The expressions ‘lutte aérienne’ or ‘bataille aérienne’, were standard ways of describing the Douhetian aerial struggle. Those who use these quotes tend to confuse these references to battles fought by opposing bomber fleets, with the battle for air superiority fought by rival fighter forces. It was the former the Army opposed, not the latter. On hearing the dreaded Douhetian ‘bataille aérienne’ mentioned yet again at a lecture in the summer of 1939, a frustrated Gamelin famously interrupted to point out that ‘There is no such thing as the “aerial battle”, there is only the battle on land.’ This did not mean he saw no need for fighters to secure the skies above the battlefield. He was just objecting to the idea that bombing cities wins wars. He was right. The Second World War was decided on the battlefield by all arms working together, not by air forces fighting their own independent bombing war.
The French Air Force failed in 1940, not so much because it was stuck in the past, but because it had been seduced by radical and unproven theories on the way air power would develop in the future. In the process, it forgot how it had used air power successfully in the First World War. France was not alone. For most of the interwar years even the German military did not believe bombers were a battlefield weapon. Initially, the fighter force had a low priority in the new Luftwaffe. Both Germany and France began revising their ideas about the same time. Crucially, the Germans had the experience in Spain and Poland to speed up the process. Even so, in 1940, the gap was not as wide as it might appear. As Liddell Hart put it, the German Army was successful not because ‘it was overwhelming in strength or thoroughly modern in form, but because it was a few vital degrees more advanced than its opponents’. With their superior tanks and growing appreciation of tactical air support, the French were arguably more than a just few degrees ahead of their British ally. In June 1940, French Army and Air Force commanders were a lot closer to understanding what was required to defeat the German Wehrmacht than their British counterparts. The loss of this expertise was as big a blow to the Allied cause as the lost manpower resources and industrial capacity. If France had managed to hang on, the war would have been won a lot sooner.