Further south, Britain’s most important ally was also in trouble. Since 10 May, French reconnaissance planes had been monitoring the powerful armoured forces moving through the Luxembourg Ardennes towards the French defences on the Meuse, and more were moving across southern Belgium towards Gembloux. Initially, the latter seemed the greater threat; there was no natural obstacle to aid the defence in the 30-mile gap between the BEF on the Dyle and the French forces on the Meuse. The well-equipped French 1st Army had the task of plugging this gap. The 2nd and 3rd Light Armoured divisions pushed as far east as possible to buy time for the French infantry to dig in.

Before the German forces could even think about breaking through the ‘Gembloux Gap’, they had to cross the River Mass, which ran through the Dutch town of Maastricht. Just a couple of miles beyond that, in Belgium, there was another major obstacle—the Albert Canal. The Maastricht crossing was not important to Dutch defences, but the local troops did their duty and destroyed the bridges over the Maas before the Germans could seize them. German forces had more success just over the frontier, in Belgium. Troops in gliders landed near the three bridges over the Albert Canal and the fort at Eben-Emael, which was supposed to cover them. Belgian engineers blew one of the bridges, but those at Vroenhoven and Veldwezelt were captured intact and Eben-Emael was quickly neutralised.

With the Maastricht bridges blown, the Belgians had the best part of a day before any major reinforcements could reach the lightly armed German airborne troops holding the Albert Canal bridges. The German forces, however, had the firepower of the Stuka dive-bombers to help them fend of the Belgian counterattacks. The Belgian troops had no air support or fighter cover; apart from escorting the odd reconnaissance mission, Belgian fighters stayed on the ground. The Fairey Fox was as capable of carrying bombs as the Fokker C.V and C.X, but these and the Belgian Battles did not intervene. The blown bridges at Maastricht caused a huge bottleneck as German columns waited for the engineers to construct the pontoons. It was one of those rare occasions where there was no alternative route. The backed-up columns made an attractive target for the eleven unemployed Hampden and Whitley squadrons, not to mention the two Whitley squadrons attempting to hit less vital communication targets further north.

Sifting through the reports coming from the front, it was not German bottlenecks the Air Staff was looking for, but rather any evidence that the Luftwaffe was bombing civilians. The cabinet meetings that day spent much time discussing whether there was justification for unleashing Bomber Command on the Ruhr, but they reached no final decision. Apart from Wellington and Whitley attacks on Waalhaven and communication targets west of the Ruhr, no other missions were flown on the night of 10–11 May. This is not to say that the French effort was more intensive—only two of the six night bomber squadrons flew. Twelve aircraft made some rather ineffectual attacks on German airfields.

Five reconnaissance Blenheims, flying singly and unescorted, were dispatched during the course of 11 May to find out what was happening in the Maastricht/Albert Canal region. Three were lost and the two that made it back were badly damaged. They confirmed the Belgian frontier defences had been breached and armoured forces were heading for Gembloux. These missions also confirmed that using unescorted Blenheims for reconnaissance was not an efficient way of acquiring information; even the Belgians were escorting their reconnaissance planes. Only the photo-reconnaissance Spitfires could operate unescorted, but No. 212 Squadron had so few planes that it rarely managed to fly more than two sorties a day. The most important role of any air force has always been and probably always will be reconnaissance. A few more reconnaissance Spitfires would have been a very good investment.

Early on the morning of the 11th, Belgian Air Force Battles attempted to destroy the two intact bridges over the Albert Canal. The Gladiator escort was intercepted before it met up with the bombers, and only one of the eight Battles returned. No bombs had hit the bridges, and the 50-kg bombs they were carrying would not have made much impression anyway. The Belgians appealed to their British and French Allies to try.

In fact, Maastricht was the more rewarding target. The bridges high over the Albert Canal could not be easily replaced, but nor could they be easily destroyed. The pontoons the Germans had thrown across the Maas were far more vulnerable and any damage to the town itself would block roads. No. 2 Group Blenheims attacked the pontoon bridges in Maastricht (eleven sorties) and enemy columns pushing towards Tongres (twelve sorties). Twelve French LeO 451s, the first of the new French bombers, also bombed Maastricht. The French bombers had a close escort of M.S.406 fighters, while the Blenheims had to rely on Hurricanes operating in the general area, but it would seem the air defences were not that strong on the 11th. Two Blenheims were lost—one to fighters and one to flak.

Instead of continuing the attack during the night, Bomber Command stuck rigidly to its pre-offensive plane to bomb communication targets west of the Rhine in Germany. Nineteen Hampdens and eighteen Whitleys bombed Mönchengladbach. It was the first time Bomber Command had attacked a German city. Four civilians were killed. How the Germans were supposed to distinguish between this and attacks on German industry east of the Rhine is not clear; nor would it have been clear to the Germans why Mönchengladbach was chosen as the crucial tactical target that merited Bomber Command’s only effort that night. Lines of communication from the city led into southern Holland and to Maastricht, but it was too far from either front line to be crucial. All the French could put into the air was five ancient Amiot 143s, but at least they were in a more relevant area, bombing Maastricht and targets around Aachen.

Fairey Battles: 12 Squadron aircraft going in against the bridges over the Albert Canal.

The fifty bombing sorties flown in the Maastricht area on the 11th were dwarfed by the number of bomber and dive-bomber sorties flown by the Luftwaffe. Nevertheless, they made sufficient impression for German Army commanders to demand better air cover. In response, on 12 May German fighter squadrons maintained a permanent watch, operating from airfields just a few minutes’ flying time from Maastricht. Operating without a close escort was now going to be very dangerous. To make matters worse, while the Luftwaffe was stepping up its efforts in the Maastricht area, Air Component Hurricanes had to divide their resources between Maastricht and the Belgian forces falling back on Antwerp. The bombers paid the price. Nine AASF Blenheims were intercepted just after attacking German troop columns and seven were shot down. Five Battles from No. 12 Squadron attempted to destroy the Vroenhoven and Veldwezelt bridges. Two squadrons of Blenheims bombing Maastricht from medium altitude were supposed to distract the defenders, but they arrived too late and the bridges were not destroyed. Ten of the twenty-four Blenheims were lost to fighters and flak, and all five Battles were also shot down.

An irate German officer scolded one of the shaken survivors:

You British are mad. We capture the bridge early Friday morning. You give us all Friday and Saturday to get our flak guns up in circles all round the bridge, and then on Sunday, when all is ready, you come along with three aircraft and try and blow the thing up!

It was a fair point. If they had struck quickly, before the defences were ready, the chances of surviving were much greater.

Other attacks on troop column heading for Tongres brought the total number of No. 2 Group sorties to forty-five for the loss of eleven Blenheims. This was an unsustainable loss rate. Fighter escorts helped the French medium bombers avoid heavy losses, but no escort could prevent eight of eighteen hedge-hopping Breguet 693 ground-attack bombers from being shot down by flak. Like the Battle aircrews, the French were flying their first mission, and they were equally taken aback by the lethality of the light anti-aircraft defences. The Breguet 693 was smaller and much faster than the Battle, but the French aircrews were no more experienced than their RAF counterparts.

Three more RAF Hurricane squadrons flew to France on the evening of the 10th, and the promised tenth squadron arrived on the 12th. Even so, the number of RAF fighters available was still inadequate for all the tasks they were required to carry out. RAF fighters were not being used as bomber interceptors deep in the rear, as Slessor and Dowding had anticipated; they were inevitably drawn to where the fighting on the ground was taking place, and the further east they went, the more frequent were encounters with Bf 109Es. Galland describes how he almost felt sorry for what he thought was a formation of Belgian Hurricanes he came across; it was actually an RAF squadron, probably No. 87. The German ace shot down two with an ease that he found embarrassing. The Battle and Blenheim raid on the Albert Canal/Maastricht bridges was supposed to be covered by three fighter squadrons, but they were committed piecemeal and engaged by German fighters over a wide area. Only the eight Hurricanes of No. 1 Squadron were in the Maastricht area, and only three of them returned intact, although all the pilots eventually made it back. Thirteen French-based Hurricanes were lost on the 12th, marking the first serious pilot losses—four killed and two wounded.

The 100-odd bomber sorties flown by the Allied air forces on 11 and 12 May in the Maastricht region caused delays, especially to the 4th Panzer. This could only help the French racing to meet them, but it was only partial compensation for the far more powerful blows that were delaying the French. These were spearheaded by the 300 Stuka dive-bombers of Fliegerkorps VIII. This mobile close-support unit had helped smash a way through the Dutch Peel Marshes defences, had beaten off the Belgian counterattacks around Eben-Emael, had forced the French tanks advancing on Breda to retreat, and was now supporting the drive on Gembloux. The idea that German Army commanders could radio for help whenever they needed it was perhaps an exaggeration, but the Germans were very good at concentrating their air resources where they were needed.

The French 2nd and 3rd Light Armoured divisions first clashed with the 3rd and 4th Panzer Divisions on 12 May. From the 13th to the 15th, a fierce tank battle raged east of Gembloux. The French suffered heavily at the hands of their more experienced opponents, but the German Panzers failed to break through. In a hard-fought and close battle, by imposing some delays, the Allied day bombers could claim to have made a small but useful contribution. Perhaps significantly, for most of the battle the French tanks were spared the full attention of the German Stukas. On the 13th, most of Fliegerkorps VIII moved south. The French thought they were dealing with the most serious threat; in fact, the heaviest German blow was to fall on the Meuse.

Since the first day of the offensive, the French had been following the progress of the Panzers heading through Luxembourg and southern Belgium towards the Meuse. On the 11th, two flights of four AASF Battles were involved in a rather ambitious attempt to bomb roads around Prüm, in Germany. Only one returned. The survivors reported that the three other planes in their flight had been shot down by flak before reaching the target. In view of the heavy losses to ground fire, Barratt suggested that the Battles should be used from a higher altitude. Playfair argued that the highest altitude for accurate bombing would still be within range of light flak, and flying as low as possible was still the best option. This seemed to be borne out in further raids on the 12th, when a first wave of three attacking from 20 feet suffered no losses, a second wave of six attacking from 100 feet lost two, and a third wave of six attacking from 1,000 feet lost four. There had been eight months of phoney war and a campaign in Norway to try out different tactics. The middle of a crucial battle was an unfortunate time to be debating solutions.

As far as the Air Staff was concerned, the losses proved they had been right all along. Portal had predicted 50 per cent losses and that was what was happening. In fact, the losses in tactical operations had been no more disastrous that those suffered in the Wilhelmshaven raids. The Air Staff’s response, however, was very different. The heavy Hampdens and Wellington losses had not been allowed to throw into doubt the validity of strategic bombing; they had just hardened Air Staff resolve to find ways around the problem. The heavy losses in tactical operations were gratefully accepted as proof that Army air support did not work.

The only problem was that the Luftwaffe was proving the contrary. The Air Staff were left sticking gamely to their argument that direct air support for ground forces only worked for armies going forward; only armies that were advancing knew what needed to be attacked, whereas armies that were retreating would always be less sure. The Air Staff liked to conjure up the image of bombers desperately scouring the countryside, looking for a particular enemy column the Army wanted bombed. In fact, in such a large-scale offensive, the bombers had no problems finding suitable targets. Their losses to anti-aircraft fire were a testament to that. Two of the raids on 12 May were actually witnessed by Guderian, the commander of the German tank forces heading for Sedan. The bombers were in the right areas.

The problem was the losses they were suffering. In critical situations, the AASF was supposed to fly repeat missions every two hours. If his had been possible, even the relatively small AASF could have had a major impact on the German columns winding their way through the Ardennes. This was what the German commanders had most feared. As it was, repeat missions were out of the question. Indeed, there were doubts about continuing to use the Battle at all in the low-level attack role. Much to their relief, the Germans were able to complete their three-day approach march to the main French defensive position along the Meuse relatively unscathed.

On Newall’s orders, Barratt instructed Playfair not to fly any missions on the 13th—the Battles had to be conserved for the decisive phase of the battle. Given the losses so far suffered, the decision was understandable. Unfortunately, the 13th was to be the decisive day of the entire campaign. This was far from obvious to the French that morning; the Germans had reached the Meuse, but all the bridges had been blown and French artillery dominated the battlefield. The French expected a pause of a few days while the Germans brought their artillery up to support a crossing of the river, and the situation seemed far more critical elsewhere. The tank battle at Gembloux was about to begin, and the French 7th Army was in difficulty around Breda, in the Netherlands. The only mission flown by the AASF on the 13th was an attempt to slow down the German advance by blocking roads in Breda. While Battles were flying all the way from Reims to support the French Army in the Netherlands, the real danger was much closer to hand.

Events on the Meuse were moving far faster than the French had anticipated. The German forces had no intention of waiting for artillery to move up. Instead, the Luftwaffe gave a classic demonstration of how airpower could substitute for artillery. Throughout the 13th, the French positions at Sedan, in the front line and artillery to the rear, were subjected to waves of medium bombers and dive-bombers. Under the cover of this continuous air bombardment, German infantry established bridgeheads on the west bank of the Meuse. So fierce was the aerial bombardment that some French troops holding the front line panicked and fled. There could be no doubt now about the impact tactical bombing could have on the battlefield. It was, however, still only German infantry on the west bank. The Panzers would have to wait until the German engineers could get their pontoon bridges across the river.

Further north, at Dinant, the German forces had nothing like the same air support. Nevertheless, at Houx, just north of Dinant, Rommel managed to get a small party of infantry across the Meuse and establish the first tiny, precarious bridgehead on the west bank. The German troops were spotted by a French reconnaissance plane. The pilot appreciated the significance of the discovery and knew what to do; following the guidelines established before the offensive for dealing with important fleeting targets, he headed for the base of No. 12 Battle Squadron. On 13 May, there could be no more important a target of opportunity than German forces on the west bank of the Meuse. Playfair wanted to strike, but Barratt, anxious to avoid unnecessary losses, denied permission. Perhaps a single strike by a squadron of Battles would not have been enough to defeat Rommel’s first attempt to cross the Meuse, but the Allies would never find out. By the evening, the bridgehead was large enough to allow work to begin on a pontoon bridge.

The French planned to retrieve the situation at Sedan by a counterattack by two tank battalions. These slow-moving infantry support tanks were quite capable of dealing with lightly armed infantry. If bridges enabled German Panzers to cross the river, the odds would swing heavily against the French. The counterattack was supposed to be launched at dawn on the 14th, but it had to be put back because of the confusion caused by retreating troops. The French desperately needed a little more time.

At 10 p.m. on 13 May, General Billotte, the commander of all Allied armies on the North-Eastern front, instructed D’Astier and Barratt to take immediate action against the bridges the Germans were building. He wanted the attacks to begin that night if possible. D’Astier immediately switched his four night bomber squadrons from the Maastricht region to the Ardennes and prepared to launch every available bomber against the bridges the following day. Barratt was more cautious. He committed himself to just one small raid at dawn.

The Meuse crossings were a much easier target for the Allied air forces than the Maastricht/Albert Canal bridges. The German fighter pilots would now be operating much further from their bases. The bridges were only temporary pontoons and they were only a short distance from Allied airfields. As Billotte appreciated, the attacks had to be launched quickly, not just because of the urgency of the situation, but to deny the Germans time to organise their air defences. On the morning of the 14th, the Germans were still desperately trying to extract flak units from the miles of columns queuing back from the Meuse.

As promised, early on the 14th, six Battles attacked the Sedan crossing points. All made it back to their base, although one wounded pilot had to force-land. Encouraged by this relative success, another flight of four was dispatched. They reported light flak, but all four returned. At 9 a.m., eight French Breguet 693s attacked armoured units spotted by the Battle crews, losing one plane. At this point, no Panzers had yet crossed the Meuse and the anti-aircraft defences were still relatively disorganised. A more substantial effort might have brought a greater reward at less cost than the British bombers were about to suffer.

Soon after these raids, the French launched their counterattack. Almost simultaneously, the 1st Panzer Division started crossing the Meuse. The French tanks advanced until they ran into the German Panzers, at which point they were quickly scattered. The situation at Sedan had suddenly become extremely critical.

French hopes of restoring the situation rested with General Flavigny’s XXI Corps, a substantial force with motorised troops, light tanks, and one of the three French heavy armoured divisions. This was moving north towards the Sedan bridgehead, with instructions to strike as soon as possible. To buy time for these reinforcements to move into position, all bombing effort was to be focused on Sedan. Barratt was persuaded to join the French in one all-out effort. At around midday, he instructed the AASF to launch every available Battle and Blenheim against the Sedan bridges that afternoon.

The French would attack first, followed by the AASF bombers. Both forces would rearm, return, and attack again. Blenheims from No. 2 Group would round off the assault. The first AASF attack would consist of three waves, with two escorted by Hurricanes and the third by French fighters. Hurricanes and French fighters would escort No. 2 Group Blenheims in the final attack. Five Hurricane squadrons would be involved; it was the first time Hurricanes had been switched from Belgium to the French front. They were joined by around fifteen now somewhat under-strength French fighter squadrons. Two of them, however, were equipped with the new Dewoitine D.520.

The RAF escorts were again indirect. At least three of the Hurricane squadrons were distracted by formations of Ju 87 dive-bombers. These were very worthy targets and the Hurricanes inflicted heavy losses, but this was little consolation to the AASF bomber crews they were supposed to be protecting. The Bf 109Es of JG 53 alone claimed thirteen Battles. Arguably, the Dutch tactics of providing a close escort, with the fighters joining in the attack if possible, would have been more successful.

It seems the French ‘escorts’ were not the standard close escort they were providing for their own bombers. At least some of the French fighters were actually escorting a French reconnaissance plane. The Bloch 152 that were supposed to be escorting the Blenheims of No. 2 Group were covering Flavigny’s forces moving up from the south. It seems the RAF was happy to accept French fighters operating in the area on other duties as an escort.

By the time the first French bombers appeared, German fighter and flak defences were ready. This first wave consisted of just twenty-one bombers, thirteen of which were Amiot 143s—obsolete, ungainly medium bombers that previously the French had only dared use by night. They did at least get a substantial escort; twelve M.S.406s flew with the bombers, while Bloch 152s and Dewoitine D.520s provided cover at a higher altitude. The French fighters fought valiantly to protect their vulnerable charges and were reasonably successful. Two Amiots were shot down by Bf 110s and another two were lost to flak, while one of the eight LeO 451s was also shot down. It could have been a lot worse.

For the AASF bombers that followed, it was a lot worse. Forty of the seventy-one Battles and Blenheims were lost to fighters and flak. So many of the returning French and British bombers were damaged that the repeat attacks had to be abandoned. Twenty-eight Blenheims of No. 2 Group attacked in the evening; only five Hurricanes could be mustered for the RAF element of the escort, and even these got side-tracked by German observation planes. Again, these were very worthy targets, but shooting down reconnaissance planes was not the role of the fighters on this occasion. Given their rather vague instructions, the pilots can scarcely be criticised for attacking any enemy aircraft they came across, but another six bombers were lost.

The dive-bombers and observation planes shot down by the Hurricanes did not help the bombers, but these successes did underline how many very vulnerable German planes there were in the battlezone. It was not surprising that Pownall was fuming at the ‘the thirty-four squadrons at home where there is no attack’. There would have been plenty of targets for them in France. Even the fighters that were available were affecting German operations. On 15 May, Guderian’s XIX Corps reported its aerial reconnaissance was ‘severely impeded’ by Allied fighters and it was no longer possible for squadrons ‘to carry out vigorous, extensive reconnaissance, as, owing to casualties, more than half of their aircraft are not now available’. It was fortunate for the Luftwaffe that so many RAF fighter squadrons were still in Britain.

During the course of the 14th, twenty-eight French-based Hurricanes were shot down. Nearly all these were victims of Bf 109s and 110s. Nineteen pilots were killed or wounded. The Hurricane was effective enough against German bomber and reconnaissance planes, but it was losing the battle with the Messerschmitts. Total Battle losses since the start of the offensive had risen to seventy—over half of the force. The AASF was withdrawn from daylight operations once again.

The French did their best to maintain the pressure on the Sedan bridgehead. During the night of 14–15 May, huge four-engine long-range Farman 222 bombers were ordered to join the tactical night offensive, but the two groups only had six serviceable machines. The four Amiot 143 bomber groups, after flying the previous night and in the daylight attack, were in action again on the night of 13–14 May; in the circumstances, the tired crews did well to manage sixteen sorties. Still the ‘heavies’ of Bomber Command remained idle. After the thirty-seven sorties flown on the night of the 11–12 May, the Air Ministry instructed Bomber Command to conserve its strength as cabinet permission for the bombing of the Ruhr was believed to be imminent. On 12–13 May, just twelve sorties were flown by the 250-strong force, and these were mainly near the Dutch/German border. On the 13th–14th, another twelve operated rather vaguely in the Eindhoven-Aachen-Maastricht region.

Bomber Command stepped up its efforts on the night of 14–15 May, but not over the Meuse. The French assured Barratt that the heroism of RAF crews had saved the day by allowing time for a French counterattack to restore the situation. Perhaps the French were slightly too enthusiastic with their appreciation; they convinced Barratt that the danger had passed. The French Air Force continued to focus on the Meuse crossings, but Barratt suggested that Bomber Command should concentrate on Breda and Maastricht. Always anxious to bomb something inside Germany, Portal added Aachen and Mönchengladbach. Twelve Hampdens attacked targets in and around Breda in support of the retreating French 7th Army, and eighteen Wellingtons bombed Aachen and Maastricht in support of the 1st Army. Twelve Whitleys revisited Mönchengladbach in support of no one in particular.

The Allied bombing at Sedan might well have helped restore the situation—if Flavigny had actually launched his counterattack. The 150 bomber sorties the Allies had flown against the Meuse bridgehead on the 14th had caused delays. Guderian’s XIX Corps reported: ‘Throughout the day all three divisions have had to endure constant air attack—especially at the crossing and bridging points. Our fighter cover is inadequate.’ These delays could have been significant. While the attacks were taking place, Guderian had decided to push his 1st and 2nd Panzer divisions as far west as possible, despite their rather precarious base. The 10th Panzer division was supposed to cover the left flank. This began crossing the Meuse on the morning of the 14th, but the air attacks meant it was not fully deployed on the west bank until the 15th. Had Flavigny’s corps attacked on the evening of the 14th, as had been the original intention, he might well have sliced between the Panzers pushing west and the delayed 10th Panzer. Unfortunately, the French could not really decide if Flavigny should attack the bridgehead or secure the left flank of the Maginot Line. Flavigny went on to the defence and the opportunity was missed.

The situation on the ground now went from bad to worse. The French forces at Dinant tried to pull back to the frontier positions they had held on 10 May, but under incessant air attack, the retreat turned into a rout. The two remaining French armoured divisions in the rear were taken by surprise by the advancing Panzers and scattered. By the morning of the 16th, the Germans had achieved a complete breakthrough along a 60-mile front. No substantial Allied units stood between the Panzers and Paris—or the English Channel.

The situation was remarkably similar to March 1918, when the Germans had also broken through on a 60-mile front. It was the scenario that the Air Ministry and Air Staff had so frequently mentioned as the only circumstances justifying the use of the ‘heavies’ in support of the Army. It had worked in 1918, when the intervention of the RFC and French Air Force had bought the Allies sufficient time to bring reserves into position. This, however, was not 1918. The Germans were now exploiting their breakthrough with fast-moving armoured and motorised forces. The Allied air forces in 1918 had been battle-hardened formations, but in 1940 they were still inexperienced. In 1918, the RFC had not suffered horrendous losses. The British and French had excellent SE5a, Camel and Spad fighters. In 1940, however, it was the German Air Force that had the best fighter operating over the battlefield. Perhaps most significantly of all, in 1918, most of the RFC was in France; in 1940, most of the RAF was in Britain.

Still, the battle was far from lost. Indeed, in the period following the breakthrough, the German forces were probably at their most vulnerable, both to counterattacks on their weakly held flanks and air attack on their lengthening supply lines. The Bf 109 had a very limited range, and the Meuse was already some way from German airfields. The Panzer forces were now racing even further west. Bf 109 squadrons began moving westwards, but the number that could be maintained so far forward was limited, and protection against Allied bomber attack could not be so effective. The French were doing their best to bring up air reinforcements to take advantage; bomber squadrons in the process of converting to modern equipment were rushed to the front. Those that were not ready were told to use their old equipment by night. French naval bombers were ordered to operate against the advancing German forces.

However, the largest single untapped bomber resource available to the Allies was the 250 Whitleys, Wellingtons, and Hampdens of Bomber Command. It seemed it was time for the Air Staff to deliver on its promise to intervene if a crisis arose.

The withdrawal from Central Norway was enough to bring down Chamberlain’s government. Winston Churchill took over on 10 May—the day Germany invaded Belgium, Holland, and Luxembourg. The most crucial battle of the war so far was underway. Losing Norway was a setback that would make winning the war more difficult, but a major defeat in France would be far more serious.

On paper, the opposing sides were evenly matched. The German Army had 136 divisions, including ten armoured divisions with 2,400 tanks. The French, with some ninety-four divisions, provided the bulk of the land forces opposing the Germans. The Belgians had mobilised twenty-two divisions and the Dutch ten. Britain added another ten. The British divisions were all very well-equipped, especially in terms of motorised transport—unlike in the Belgian, Dutch, French, and German armies, there was not a horse to be seen. They were, however, all infantry divisions. Britain’s first armoured division was still forming. The only British armoured unit in France was the 1st Tank Brigade, with around 100 slow Matilda infantry support tanks. The French had over 3,000 tanks. Half of these were concentrated in six armoured divisions (three light and three heavy), while the remainder were with infantry support battalions.

The Allied forces lacked combat experience and they were facing battle-hardened troops, experienced commanders, and outstanding generals. The first serious fighting was bound to be a severe test for everyone on the Allied side, from the humblest private to the generals at the top. In these circumstances, initial setbacks were perhaps inevitable—a retreat an acceptable price to pay for the experience gained.

In the air, on the north-east front, the French had seventeen fighter groups, each with two squadrons, totalling around 500 planes. Eight groups had the M.S.406, five the Bloch MB-152, and four the American Curtiss Hawk. There were another eight groups in the south, which were either available to deploy further north or were reequipping with more modern planes. The fighters available were broadly equivalent to the Hurricane—slower than the British fighter, but more agile. With one or two cannon, the French-designed fighters were also better-armed. The French were well-aware that they did not yet have an engine that was the equal of the British Merlin or German DB 601. Their fighters could not match the 354 mph of the Bf 109E, but they were closing the gap with the Dewoitine D.520 (330 mph) and Arsenal VG-33 (347 mph). The first units with the former were about to become operational, and the latter was just beginning to roll off the production lines.

The first squadrons with a new generation of French bombers and American Douglas DB7 and Martin 167 imports were also about to become operational. The only bombers immediately available on 10 May were two squadrons with the rather old-fashioned looking but efficient four-engine Farman 222 heavy bomber and four squadrons of obsolete Amiot 143s. The French also had around 150 reconnaissance and nearly 400 army-cooperation planes distributed amongst its armies.

The Dutch and Belgian Air Forces added another 300 combat planes to the Allied cause. The Dutch Air Force relied almost entirely on designs produced by Anthony Fokker, including the manoeuvrable Fokker D.21 single-seater (three squadrons), the twin-engined eight-gun Fokker G.1 (two squadrons), a squadron of Fokker T.V bombers, and less-modern Fokker C.V and C.X biplane reconnaissance bombers. There was also a squadron of American Douglas 8A-3N attack bombers, which the Dutch were planning to use as fighters. The Belgians mustered six fighter squadrons (one Hurricane, one Gladiator, two Fiat CR.42s, and two Fairey Fox VIs), one bomber (Fairey Battle), and nine reconnaissance/army-cooperation (Fairey Fox and Renard R.31) squadrons.

With the RAF possessing around 1,900 planes, once all the French squadrons were available, the combined Allied air forces would not be far short of matching the 4,500 planes the Luftwaffe possessed. The war was on a knife edge. With modern planes arriving and production increasing, the French Air Force was a rising force. Britain was in the process of creating a powerful army, and Belgium and the Netherlands provided valuable manpower resources. If the four Allies could weather the initial storm, victory might not be too distant a prospect. With 900 fighters and 650 bombers, the RAF was capable of making a substantial contribution to ensuring the German offensive did not succeed.

This was not how the Air Staff saw it. Preoccupied with visions of wars decided by long-range bombing, they could not see the danger. They ignored warnings that unless the Allies threw everything into the initial battle, they might suffer a major defeat. Instead, they were convinced the land battle could not be decisive. It was the battle of the bombers that would decide the war. Eighteen of the twenty Wellington, Hampden, and Whitley squadrons were being held back for the attack on the Ruhr, which was where the real battle would begin. Even the two Whitley squadrons assigned the task of attacking German Army communications were, as Portal put it, merely a way to ‘forward our plans towards the destruction of the German war industry’. The targets the Whitleys bombed were to be as close to the Ruhr as possible.

Of the forty-three fighter squadrons in the UK, four would fly to France as soon as the German offensive began. Of the rest, four (two Hurricane and two Blenheim) were to patrol the English Channel, providing flank protection for the French 7th Army. Two more were earmarked for Norway, leaving thirty-three—including all nineteen Spitfire squadrons. The Royal Air Force was not going to over-commit to a battle that could not be decisive.

On 10 May, German forces started moving forward on a 300-mile front from the north of the Netherlands to Luxembourg. The advance was spearheaded by ten Panzer divisions. One was heading for Rotterdam, four for Gembloux and Dinant in Belgium, and five for Montherme and Sedan in France. In the early hours of the 10th, a first wave of 500 German bombers set off in small formations to attack seventy-two French, Dutch, and Belgian airfields. Around 100 Allied combat planes were destroyed. The Dutch suffered the most heavily. The airfields were as far west as possible to try maximise warning time, but the German Air Force simply flew out into the North Sea and attacked from the west. Warning was virtually zero. Twenty-eight aircraft were destroyed on the ground; one Fokker G.1 squadron was wiped out.

The Belgian Air Force also suffered heavily in these first attacks. Most of the sole Hurricane squadron and one of the Fiat CR.42 squadrons was destroyed. The RAF and French Air Force emerged relatively unscathed. One French MS 406 squadron and, much later in the day, one AASF Blenheim bomber squadron lost virtually all their planes. The second wave of German bomber attacks found the defences largely intact. Around 500 bombers, again mostly flying in small formations, struck around 150 communication targets, many deep in the Allied rear, beyond escort range.

No. 615 Squadron was still converting from Gladiators to Hurricanes and not available, but from dawn on the 10th the other five RAF fighter squadrons were fully engaged. They found themselves dealing largely with the unescorted bomber formations they were trained to deal with. Around 200 sorties were flown and the pilots claimed forty-two victories. Fifteen Hurricanes were lost or crash-landed; six pilots were wounded, but none killed.

The Dutch response was ferocious and effective. Even the Fokker T.V medium bombers took off to engage the waves of bombers and Ju 52 transports. It was a desperately difficult situation. Fighters scrambled as bombs fell around them and pilots found themselves having to deal with powerful fighter escorts. Twenty Dutch fighters were shot down to add to the twenty-one already lost on the ground. However, despite the losses—and the odds against them—the survivors were soon flying their second mission of the day. During nearly 100 fighter sorties, twelve bombers, seven transports, and eight Bf 109Es were claimed, matching the success rate of the RAF squadrons. By contrast, most of the Belgian fighter squadrons spent the day moving from one airfield to another, trying to avoid the catastrophic losses their Dutch neighbours were suffering. This might have made sense if what was happening were the first tentative moves in a long, drawn-out struggle, but as the Dutch appreciated, events were moving fast. The Belgians did not escape heavy losses either. During the day, around forty of their combat planes were destroyed on the ground, including twenty-three fighters.

French fighter squadrons were not operating in quite such difficult circumstances as their Dutch and Belgian allies, but encounters with escorts were not rare. The thirty-eight French fighter squadrons engaged managed around 360 sorties, claiming forty-four planes. In total, the Allies flew around 800 sorties on this opening day, compared to the 2,000 flown by the German fighter force. German losses closely matched Allied claims, with 120 combat planes lost or written off. Of these, around 100 were bombers, representing 7 per cent of the available force. Many more returned damaged with dead and wounded aircrew aboard. It was a loss rate that the Luftwaffe could not afford to suffer too often. The next day, medium bomber sorties dropped from around 1,500 to 1,000.

Luftwaffe bomber losses were heavy, but RAF losses were catastrophic. At 10.30 a.m., Barratt arrived at the joint RAF/French Air Force headquarters in Chauny. He discussed with d’Astier reports from French reconnaissance of German columns moving through Luxembourg, and at 12.20 p.m. he ordered his bombers into action. Thirty-two Battles from seven squadrons were sent off, flying at low-level in flights of between two and four aircraft. Fighter support was provided for the first ‘wave’ of eight, but it consisted of just five Hurricanes from No. 1 Squadron and three from No. 73 Squadron. These were supposed to patrol over the city of Luxembourg and clear the area of enemy fighters. The number of fighters was ludicrously small for the task, and the two formations were not even working together. Given the rather vague nature of their ‘escort’ orders, it is not surprising that the three Hurricanes of No. 73 Squadron should turn their attention to some apparently unescorted German bombers they came across. In fact, there was an escort. The Hurricanes were bounced before they reached the bombers and at least one was shot down. By chance, No. 1 Squadron Hurricanes saw the difficulty their comrades were in but were flying too low to offer any help. If the two formations had been working together as a team, one providing cover at altitude, the interception might have been more successful.

Meanwhile, the Battles were heading for their targets at treetop height. The low-level approach helped avoid enemy fighters, but the hail of light flak that greeted them over their targets proved just as deadly. A flight of two from No. 12 Squadron attacked from 30 feet. As the two Battles manoeuvred into position to fly down the road, one of them was shot down before it got close enough to drop its bombs. The second, piloted by Flt-Lt Simpson, strafed the enemy column with the single forward-firing machine gun as he dropped his bombs. It must have been frustrating for the pilot to attack with such boldness and have only a single machine gun to take on the targets ahead of him. Simpson was convinced he could not miss his target from such an altitude, but neither could the German defensive fire. He was immediately hit and forced to crash-land in a nearby field. Of the thirty-two Battles sent out during the course of the afternoon, thirteen suffered a similar fate.

It was a disastrous operational debut for the Battle as a tactical bomber. British plans for tactical air support were in tatters. Flying high, the Battles were vulnerable to fighters; flying low, they were equally vulnerable to ground fire. The columns the Battles attacked were not even high-value targets the Germans might feel a particular need to defend. They were just random columns.

It was the first of many such expensive raids that would seal the Fairey Battle’s reputation as one of the worst planes ever to enter service with the RAF. A plane designed to carry enough fuel to fly 1,000 miles was never going to be ideal for short-range, low-level tactical bombing. The proposed extra armour might have helped; the promised self-sealing tanks had also not yet arrived. Perhaps even more significant was the inexperience of the aircrews, who were using these low-level tactics in action for the first time. Determined not to waste their bombs, pilots were perhaps taking too long to line up the target. Some of the attacks seemed to have taken place in the sort of flat terrain where the enemy was very visible, but equally the anti-aircraft defences had plenty of warning of the approaching bombers. With experience, pilots would come to learn that successful ground attack in any aeroplane relies on using the surrounding terrain as much as possible and delivering the attack quickly, sacrificing precision for the chance to fight another day. The AASF really needed to have found out about the problems in a non-critical situation, during the ‘Phoney War’, as Bomber Command had—not at the start of a crucial battle. With more experience, and with the extra protection Brooke-Popham had proposed, the Fairey Battle could have been a lot more effective.

Initially, the forces the Battles were attacking did not appear to be the most serious threat. The terrain in the Ardennes did not seem particularly suitable for the movement of substantial motorised forces, and they had some way to go before they even reached the main French line of defence along the Meuse. The Panzers thrusting through the plains of southern Belgium and westwards towards Rotterdam seemed far more dangerous.

As soon as the German forces invaded Belgium, the BEF headed for the Dyle. Further south, the French 9th Army took up position on the Meuse at Dinant. The French 1st Army, with two of France’s precious armoured divisions, rushed to fill the gap between the two rivers. Another French armoured division (1st Light Armoured) raced through northern Belgium to link up with French forces landing at Flushing. The combined force was then supposed to push north and secure a link with the Dutch. While the British and French moved into position, the brunt of the initial German assault would be met by the Belgian Army, along the Albert Canal, and Dutch forces, defending Fortress Holland.

The Dutch were relying on the natural obstacles provided by the Zuiderzee in the north and the numerous waterways at the mouth of the Maas in the south. In the west, the main defensive position was the Grebbe Line running along the Geld Valley. Behind that was a fallback position running from just east of Amsterdam to the east of Rotterdam. Both lines took maximum advantage of low-lying land that could be flooded. South of the Maas, the Peel marshes were only lightly held. The Dutch had chosen the shortest and easiest lines to defend. The disadvantage was that their main southern defences ran parallel to the Belgian northern Albert Canal defences, leaving a corridor between for the Germans to advance through.

The German High Command hoped to eliminate Holland on the very first day by landing troops inside ‘Fortress Holland’. Airborne troops were to capture three airfields (Ypenburg, Ockenburg and Valkenburg) around The Hague, from where they would push into the city and capture the Dutch Royal family. If this failed, paratroopers dropped on the Moerdijk, Dordrecht, and the Willemsbrug bridges and Waalhaven Airfield would clear a path for the 9th Panzer Division racing through southern Holland.

The German forces that landed in and around The Hague were soon in trouble. Many of the Ju 52 transports were either shot down, destroyed by obstacles erected on the airfields, or simply found the Dutch airfields were unable to support their weight. The damaged and wrecked planes that littered the airstrips prevented the follow-up waves from landing. Many had to force land on any nearby flat land they could find. The surviving German troops were soon fighting for their lives. Forty ground-attack sorties flown by Dutch fighters and light bombers supported the Dutch counterattacks. Further east, Dutch forces withdrew in fairly good order to the Grebbe Line. In the south, Panzers and the Ju 87 dive-bombers of Fliegerkorps VIII, the Luftwaffe’s short-range close-support force, had little difficulty blasting their way through the weakly held Peel Marsh defences.

As soon as the attack was underway, the air attaché informed the Dutch Army commander about the RAF plans to bomb advancing German columns, provided their location could be established. At 7.30 a.m., the Dutch told the air attaché that the German forces landing at Waalhaven were the most serious threat and asked for the airfield to be bombed. The message was passed on to London. When no attack came, the air attaché was bombarded with calls emphasising how critical the situation was becoming and demanding to know what was holding up the RAF.

The message certainly got through to Newall. Armed with the information provided by the air attaché, Newall told the morning cabinet meeting that the Dutch had matters in hand around The Hague, but Waalhaven was a problem and six fighter Blenheims were being sent to strafe the airfield. Newall explained that he had decided not to use bombers because of the risk of civilian casualties. In fact, Dutch aircraft were already bombing their own airfields. The six Blenheims were in fact the only Air Ministry attempt to implement the fighter support the Air Ministry had promised. Their primary mission was to shoot down enemy aircraft and only strafe the airfield if none were encountered.

By midday, requests were coming from Barratt in France for Bomber Command to intervene in the Netherlands. The missions subsequently flown appear to have been based on information gathered by reconnaissance planes rather than as a response to requests from The Hague. Twenty-four Blenheims attacked German forces in The Hague region, where, as Newall had explained to the cabinet, the Dutch felt they were in reasonable control. Twelve of the planes bombed Ypenberg Airfield after it had been recaptured by the Dutch. Early in the afternoon, nine Blenheims bombed Waalhaven. This was the only RAF bombing attack on the airfield that day, and even this appears to have been a response to Barratt’s demand for some action rather than the Dutch pleas via the air attaché. Three of the thirty-one Blenheim bombers were lost—ironically, two of them shot down as they attacked the recaptured Ypenburg Airfield. The Blenheim fighters operating over Waalhaven did not fare so well. The original plans for protecting Dutch airfields had proposed using Spitfires or Hurricanes where possible—using Blenheims would be risky. So it proved. Five of the six Blenheims were shot down by Bf 110s.

The next planned Bomber Command support for the Dutch was to be the attack on the Ruhr. The Air Ministry was expecting the government to give the go-ahead for the operation that night. The desperate appeals to do something about the growing strength of the German forces holding Waalhaven seemed to be falling on deaf ears.

By the end of the day, Dutch counterattacks had recaptured all the occupied airfields except for Waalhaven. Fortunately for the Dutch, the British Government did not authorise the Ruhr operation. A frustrated Portal ordered the Wellingtons of No. 3 Group to attack Waalhaven instead. The Dutch lit a bonfire to guide the bombers in, and thirty-six Wellingtons kept up a steady bombardment throughout the night. Flying at little more than 2,000 feet, the Wellingtons dropped 58 tons of bombs on the beleaguered German forces. The Dutch were delighted, and at 5 a.m. they requested a halt to the bombardment so that they could launch their next counterattack. Less appreciated or indeed even noticed were the nine sorties flown by the two Whitley squadrons against bridges just over the Dutch border, in German territory.

On the morning of the 11th, the Dutch attempt to retake the airfield failed. The RAF was asked to resume their bombardment while the few remaining serviceable Dutch planes focused their efforts on the German troops still holding both ends of the nearby Willemsbrug bridge. The aim at this stage was not to destroy any of the captured bridges. The Dutch wanted them intact so that the advancing French could use them to reinforce Fortress Holland. In the morning, and again in the afternoon, the two surviving Fokker T.V bombers, flying low and escorted by Fokker D.21s, scattered 50-kg bombs on the German troops around the bridge. The RAF attacks on the airfield, however, did not materialise; indeed, the air attaché was informed that there would be no more attacks. No reason was given. At around midday, an embarrassed air attaché told the Air Ministry the Dutch were ‘seriously upset’ by the decision and were pleading for it to be reconsidered. A succession of Dutch Army officers turned up at the embassy to emphasise the huge importance of eliminating the besieged German forces holding Waalhaven. The Dutch ambassador in London was told to try and speak to Churchill in person.

On the 11th, Fighter Command was more active over southern Holland. Crowds cheered as Hurricanes patrolled The Hague. However, a patrol by twelve Hurricanes of No. 56 Squadron in The Hague-Rotterdam area ended in disaster when the formation was surprised by Bf 109s and five were shot down. The next day, two out of a flight of three Blenheims were lost. A flight of three Spitfires was caught by Bf 109s, losing one of their number.

For many of the British-based pilots, this was their first experience of combat. The circumstances could not have been more demanding. They were not trained in fighter-versus-fighter combat, and they were confronted by confident, experienced Luftwaffe fighter pilots. They were operating in small numbers—often lone flights of six, sometimes just sections of three—so they were invariably outnumbered. Operating in these circumstances, so far from their home bases, was not the ideal way to gain combat experience.

Something had to be done about the way British fighters were being taken by surprise and picked off by the high-flying German Messerschmitts. Instead of changing the tight vic formations that were largely responsible for the problem, Defiants were assigned the task of covering the rear. It was a chance to test the theory that the turret fighter could be used to establish air superiority in skies dominated by the enemy. The composite Defiant/Spitfire formation had its first real test on the 13th. The formation was engaging Ju 87 dive-bombers west of Rotterdam when it was bounced by the German escort. The German pilots might well have mistaken the Defiants for defenceless single-seaters and been surprised by the defensive fire that greeted them, but their surprise was short-lived; five of the clumsy Defiants and a Spitfire were shot down for the loss of just one Messerschmitt. It seemed fairly conclusive proof that Dowding had been right—using the Defiant offensively could be no more successful than Trenchard’s offensive F.E.2 patrols of the First World War. However, the advocates of the turret fighter were still not convinced. The Defiants had claimed four Ju 87s before the German fighters intervened, and this was enough to ensure the experiment continued—once the battered Defiant squadron had recovered.

On the ground, the situation in the south of the Netherlands was already becoming critical. On the 11th, forward elements of the French 7th Army approaching Breda were brushed aside by the 9th Panzer and its supporting Ju 87 dive bombers. The French instinctively sought sanctuary in a safe defensive line and lost all interest in helping recapture the Moerdijk Bridge. General Winkelman, the Dutch Army commander, now realised that there was little likelihood of any help from the French; the only hope was to try and destroy the captured bridges to the south of the city and hang on in Fortress Holland. The Grebbe Line was just about holding. The main Dutch concern was still the German forces clinging on to their foothold inside Fortress Holland, around the Willemsbrug Bridge and nearby Waalhaven. The air attaché in The Hague was still furiously relaying Dutch appeals for air support to the Air Ministry, but getting no response. In desperation, the Dutch asked the military attaché at the embassy to pass on a message via the War Office, begging ‘most earnestly’ that Waalhaven be bombed. The only response came from the Navy; while Portal’s bombers waited for permission to bomb the Ruhr, at dusk on the 12th, six Coastal Command Beauforts and nine Fleet Air Arm Swordfish attacked the airfield. By this time, the 9th Panzer Division had reached the German paratroopers holding the Willemsbrug Bridge.

The Dutch did the best with their own dwindling air resources. After flying most of its ground-attack missions on the 10th without fighter escort, for the remainder of the campaign the Dutch Air Force provided their low-level bombers with close escorts. This put the fighters at a tactical disadvantage, but it did mean they could actually help the bombers if they encountered enemy fighters. If no enemy fighters were around, they were in a good position to join in the attack. Anthony Fokker had lost none of his flair for designing fighters; the Fokker D.21, with its fixed undercarriage, might have lacked the speed of more modern fighters, but its superb handling and agility gave the Dutch pilots a fighting chance. With an escort, the hedgehopping Fokker C.V and C.X biplanes managed to deliver their attacks without incurring the crippling losses suffered by the Battle squadrons.

On the third day of the invasion, the Dutch Air Force was engaged all along the front. Operating from emergency airstrips away from their main airfields, ground-attack missions were flown against German forces threatening the defences that secured the northern end of the dyke at the mouth of the Zuiderzee. Retreating remnants from The Hague landings, trying to fight their way south to Rotterdam, were also targeted. Waalhaven was bombed. Troop columns and artillery positions around the Wageningen sector of the Grebbe Line, where the Dutch defences were under particular pressure, were also attacked. The numbers were tiny—the largest operation was just seven Fokker C.Xs with six Fokker D.21s escorting. The smallest was a lone Fokker T.V with a single D.21 escort. The attacks may not have been devastatingly effective, but they were at least in the areas the Dutch Army needed them. Just the sight of their own planes roaring in at low level raised the spirits of the Dutch troops.

By the evening of the 12th, German troops had achieved a shallow penetration of the Dutch defences in the Wageningen sector, forcing the Dutch back to their last line of defence. The Grebbe Line was in danger of collapsing. The Dutch Defence Minister personally asked for the RAF to bomb the Moerdijk Bridge (to halt the advance from the south) and the roads leading to Wageningen (to slow down the German advance from the east). He was told the bridge was far too solid to be destroyed by air attack, which was true, and that attacks on roads could only bring temporary relief. This was also true, but that was what was all the Dutch wanted. No. 2 Group in East Anglia could not help, but, rather bizarrely, the Dutch request was passed on to Barratt in France to see if his Battle squadrons south of Reims could lend any support.

Dutch frustration was growing. The Air Ministry had refused Dutch pleas to base RAF squadrons in the Netherlands. Could they at least use Dutch airstrips to refuel, as French aircraft were doing? The Air Ministry came up with all sorts of reasons why this was impossible: Dutch fuel hoses were the wrong size; British planes needed different fuel. In truth, if the Air Staff and Dowding were reluctant to send fighters to France to support the British Army, they were hardly likely to send them to the Netherlands to support the Dutch Army. The Dutch were told that there were always more crucial battles elsewhere and the RAF was needed there. This was true, but it was not true that the RAF was fully engaged in these crucial battles. Most of the Wellington, Hampden, and Whitley squadrons were just sitting on their airfields, waiting for the offensive against the Ruhr to start. Two-thirds of RAF fighter squadrons were waiting for the German bombers to come.

Dutch pleas now became ultimatums. The Dutch Foreign Minister spelt it out—first to members of the Air Staff, and then to Ismay, Churchill’s military advisor. Either the British provided air support or the Dutch government would have to consider surrendering.34 No assurances were forthcoming, and the Dutch government and Royal Family prepared to leave the country. Winkelman was given full authority to cease fighting if he judged the military situation had become hopeless.

Far from stepping up its efforts, Fighter Command was reducing the scale of its operations. Too many fighters had already been lost. Cover was provided for the evacuation of British citizens from Ostend and the Dutch Royal Family and government from The Hague, but there was nothing in the key battlezone. Early on the morning of the 13th, the last Fokker T.V, escorted by two Fokker G.1s, set off for the Moerdijk Bridge with 300-kg bombs. The damage these large bombs could inflict on the huge structure was never put to the test; only one hit the bridge, and it failed to explode.

On the Grebbe Line, a Dutch counterattack on the morning of the 13th on the Wageningen sector was defeated by heavy German artillery and Luftwaffe air support. A withdrawal to the final ‘Fortress Holland’ line became the only option. With the Luftwaffe dominating the skies, this was not possible until the sun had set. It would be a desperately difficult day for the Dutch Army. Low cloud provided some respite from German air strikes, and despite the weather, the Dutch Air Force was still flying and provided as much support as possible. Around twenty Fokker D.21s, C.Xs, and G.1s strafed and bombed German artillery positions and troops in the Wageningen area. Yet another plea to the British Embassy revealed the staff had joined the exodus to Britain. Despite the problems, during the following night the Dutch forces successfully withdrew along the entire front to their last line of defence.

On the morning of the 14th, the situation looked relatively stable. The Dutch forces were well-established in Rotterdam; the German forces holding the northern end of the bridge could not be dislodged, but Dutch guns were preventing any movement across the waterway. In the east of the country, the Germans were only slowly following up the Dutch withdrawal from the Grebbe Line. Hitler, frustrated by the slow progress, ordered an intensification of effort on all fronts. An assault on Rotterdam would be preceded by the bombing of the Dutch Army positions on the north bank. The target area would stretch as far as the city centre. The Dutch were warned an air attack was on the way and given one last chance to surrender.

Winkelman was not convinced there was any immediate need to surrender. The Dutch were certainly in no hurry to come to a decision—there was no reason to fear this particular German bomber threat more than previous bombing. The German Air Force had been bombing the country for four days. A second deadline was approaching and the negotiations were still in progress. Ninety He 111s of KG/54 were already heading for Rotterdam. The German commander tried to delay the attack, but only half the force saw the warning red Very lights. Fifty-four Heinkel bombers dropped 97 tons of bombs on the designated target area. There was no anti-aircraft defence, and the last serviceable Dutch fighters, five Fokker D.21s and five G.1s, were further north, providing cover for the troops still pulling back from the Grebbe Line. The Heinkels were able to drop their bombs with precision from 2,000 feet.

Unopposed bombing from low level can be particularly destructive. Even so, nobody anticipated what was about to happen. The bombs were high-explosive rather than incendiary, but the target area contained warehouses full of inflammable produce. These were among the first buildings to be hit, and flames soon engulfed the wooden houses of the historic city centre. One square mile of the city was devastated; 800 people lost their lives. Winkelman was severely shaken by the scale of the destruction. The German commanders on the spot were just as stunned. The German propaganda machine was quick to exploit the situation. If the Dutch did not surrender, a similar fate would befall Utrecht, which was also now in the front line. Winkelman ordered all Dutch forces on the mainland to lay down their arms.

At the time, the death toll in Rotterdam was put as high as 30,000. It seemed the prophets of doom had been right; bombing alone could bring a country to its knees. Whether the same decision would have been made if the bombing had occurred on 10 May, with Allies apparently coming to Holland’s aid, is open to question. By the time the attack was launched on the 14th, the Dutch government had in principle already taken the decision to surrender. Nevertheless, for the Air Staff it was conclusive proof of how destructive and decisive bombers could be and a reminder of why Britain had to keep fighters back to defend British cities.

Lack of British support was not the only reason for the Dutch defeat, nor even the main one. The French reluctance and inability to engage the Panzers in mobile warfare around Breda was at least as significant. Nevertheless, the Dutch might have reasonably expected more support from a major military power like Britain. Given the importance attached to preventing the Netherlands from falling into German hands, Britain might have been expected to provide it. Not even the fear of invasion or heavier bombing raids on London, or the advantage of having friendly territory on the approach to the Ruhr, could induce the Air Staff to use the RAF as Dutch Army commanders wanted.

Another useful ally had been lost to the Allied cause. It was one thing to allow Poland, a valiant ally on the other side of Europe, to be overwhelmed by a powerful neighbour, or indeed Norway, a nation many hundreds of miles from our shores. It was quite another matter to allow a similar fate to befall an equally valiant ally just the other side of the North Sea. Britain could not afford to lose allies so easily.