To his contemporaries, the most ridiculously risky decision Hitler ever took was to invade Western Europe and try and conquer France in the spring of 1940. ‘None of the higher headquarters think that the offensive has any prospect of success,’ wrote General Franz Halder, Chief of the German General Staff, in his diary on 3 November 1939.ⁱ And Halder was not alone in thinking Hitler was mad to contemplate invading France. ‘It’s not for nothing that the Commander of the German navy is in a thoroughly suicidal mood in the autumn of 1939,’ says Professor Adam Tooze, talking of the disquiet in the higher reaches of the German Armed Forces. ‘It’s not for nothing one of the key figures in the German army is going to his meetings with Hitler with a loaded pistol in his pocket, and but for his oath of loyalty which ran deep in somebody whose entire family had for generations served in the German army, would have quite happily assassinated Hitler.’

All of these military experts were against Hitler’s decision to mount an offensive against the West simply because they thought the Germans lacked the capacity to gain victory. As Professor Tooze says, Hitler was proposing an operation that was ‘phenomenally high risk’ and one which could well lead to a ‘catastrophic defeat’ for the Germans.

Not only did Allied forces possess more tanks than the Germans in the spring of 1940, the British and the French tanks were better. Generals in the French High Command, in particular, were brimming with confidence about their ability to repulse any German offensive in the spring of 1940. Indeed, the commander in chief of the French army promised that Hitler would ‘definitely’ be beaten.ⁱⁱ

It’s also a myth that the Germans were contemplating an offensive in May 1940 that would use revolutionary military tactics. In fact, they relied on traditions deep within the German army. ‘Frederick the Great, back in the 18th Century, laid out Prussian tactical doctrine: the Prussian army always attacks,’ says Professor Robert Citino, who until recently taught at the US military academy at West Point. ‘He had a standing order for his cavalry forces that they must always get their charge in first and not wait to be charged by the enemy. That notion of a kind of bulldog level of aggression coupled with repeated manoeuvre had been a German tradition for a good long time. I’m not sure it had ever really been a British tradition, it had arguably been a French tradition during the reign of the great Napoleon, but certainly not in other periods or times of French history… what they [the Germans] were really trying to do [in spring 1940] was restore a very old way of war.’

Nor was the original German plan to invade Western Europe something new. In fact, it was a variant on the Schlieffen Plan which had been used in the First World War – a sweeping attack through Belgium and the Netherlands towards France. And if the Germans had actually put this plan into operation it would almost certainly have led, as it did in the First World War, to a long and bloody stalemate which would eventually have brought German defeat.

But the Germans didn’t go with this original idea; partly because the Allies captured a draft of the plan when a German plane crashed over Belgium in January 1940, and partly because Hitler had always been inclined – like the gambler he was – to go for something more spectacular.

That spectacular option was offered by the ambitious General Erich von Manstein (though many others would also later claim authorship of this new plan – as the old saying goes: ‘success has many fathers – failure is an orphan’.) Manstein – supported by Heinz Guderian, the most brilliant tank commander of the war, and General Gerd von Rundstedt, who would command Army Group A in 1940 – suggested to Hitler that the main offensive against the West should not come through Belgium and the Low Countries, but instead further south, through the forest of the Ardennes, directly into France around Sedan. There would still be an attack through Belgium by German Army Group B, but this would be designed to make the Allies think that the Germans were mounting a conventional attack – as a consequence, the advance of Army Group A would take them by surprise.  

‘The Panzers of Army Group A would slice through the Ardennes and then make this race West to cut off a large fraction of the French army and the entire British army and then annihilate it,’ says Professor Geoffrey Wawro. ‘But the risks were tremendous. You’re talking about seven armoured divisions against this large French army and this large British army, racing to the coast, exposing a flank 300 kilometres long with no supporting infantry behind them; a tremendous risk. But the German Generals, Manstein, Rundstedt and Guderian, were confident that the shock and awe of that kind of approach would so disable the French and the British that they’d win.’

‘This is an operation of unprecedented logistical risk,’ confirms Professor Adam Tooze, 'and gives the opponents of Germany - Britain, France, Belgium and Holland - the chance, if they’re sufficiently well organised, to mount a devastating counterattack on Germany and on the pincer moving across Northern France. And for this reason the Germans fully understand that if this plan fails they’ve lost the war.’

On 10 May the Germans attacked. And to begin with, as the Germans had hoped, the Allies were totally deceived about the true location of the Wehrmacht’s main attack. At French military headquarters one officer heard the remark: ‘See how the General was right to attach no importance to anything except the north-eastern front!’ⁱⁱⁱ

The overconfidence – almost arrogance – of the Allies was one of the key reasons why they would be defeated so quickly and so comprehensively in the battle for France. Because even when reports began to come from the southern sector that there were German troop movements around the Ardennes, there was little urgency to react. Since the British and French appeared to be holding the Germans in Belgium and the Netherlands, along the northern front, what damage could what was perceived as a ‘diversionary’ attack through the rough terrain of the Ardennes do?

The answer was plenty. In one of the most astonishing feats of modern warfare German armoured units managed to move through the Ardennes and then cross the river Meuse in France by 13 May – within three days of the battle starting. The Allies had planned that their defensive forces in this area would gradually retreat in the face of a German attack to the line of the Meuse, and then hold at the river and wait for reinforcements. But that plan was now blown to pieces.

‘They [the Allies] were absolutely unprepared,’ says Professor Wawro. ‘I mean the irony is that Colonel J.F.C. Fuller and Liddell Hart and other Brits during the inter-war period had been talking about tanks and armoured warfare and the need to administer a ‘shock to the brain’ instead of getting into these attritional slugging matches from trench lines in the sort of ‘French style’ methodical battle. They’d been talking about using armoured spearheads to administer a ‘shock to the brain’, which is exactly what the Germans did when they broke through and cut behind the French and the British; they paralyzed and demoralized them. They didn’t destroy the fighting effectiveness of those units, they just completely discombobulated them.’

When, on 14 May, Sedan fell to the Germans, the French political leadership were certainly ‘completely discombobulated’. In the early hours of 15 May, Paul Reynaud, the French Prime Minister rang Winston Churchill, who had been Prime Minister for less than a week. Reynaud opened the conversation with the words: ‘We have been defeated!’

And the spirit of many of the Generals commanding the French army was just as shattered. Captain Beaufre of the French High Command, wrote: ‘I must confess that the morale of the French High Command was very quickly broken. In fact, the night when we happened to know that the front had been broken through at Sedan, at that time the feeling was that everything was lost. I saw General Georges, who was commanding the north-eastern front. I saw him sobbing and saying, ‘There have been some deficiencies’.^iv

German Army Group A now dashed towards the French coast, reaching the mouth of the river Somme on the English Channel by 20 May. The main British and French fighting force was now trapped north of them, between the twin spearheads of Army Group B and Army Group A. The British, as a consequence, had no alternative but to fall back to the French coast themselves – at Dunkirk.

But then something very strange happened. Something that has been debated ever since. On 24 May the Germans decided to halt their advance and not move forward to crush the Allied troops in Dunkirk. Various theories have been advanced as to why this delay was agreed. Was Hitler deliberately allowing the British to escape because he wanted to make peace with Great Britain? Or were the German troops simply exhausted? What exactly happened in that vital meeting on 24 May, attended by Adolf Hitler and the German commander, General Gerd von Rundstedt?

Well, Professor Sir Ian Kershaw has made a careful study of that decisive conference, and he is in no doubt about the reason for the halt order: ‘What Hitler was doing there on the 24th May 1940, that crucial day, was actually agreeing to the suggestion put forward by the commander of the German forces in the west, General von Rundstedt, who then wanted to preserve the tanks for what they saw as a greater need, which was to destroy the French troops by moving south against them. And Goering had promised Hitler that the British troops would be bombed to bits from the air anyway.’

For the soldiers of the British Expeditionary Force who had retreated to Dunkirk, this delay was a godsend. It meant that they had time to prepare the defence of the town, and the British navy had time to organise an evacuation. And though Luftwaffe planes did indeed bomb Dunkirk, they didn’t manage to destroy the armies sheltering there. So as a result, at dawn on 27 May, the halt ordered was reversed and the German army began to advance.

As the Germans attacked, several hundred thousand Allied troops on the beaches around Dunkirk still waited patiently to be rescued. ‘It was just queues,’ says Edward Oates, one of the British soldiers who was trapped at Dunkirk, ‘queues of men… and people going out into the water. And, of course, the Germans kept coming over, planes, we had to keep dashing up to the dunes to stop being hit… One [soldier] was hit by shrapnel, and I can’t remember who it was, but I can remember he was laying down there shouting out, ‘My back! My back!’

More than 800 civilian vessels – fishing boats, pleasure steamers, tugs – arrived to help ferry the troops across the Channel to England. But contrary to later myth, the majority of soldiers were rescued not from the beaches, but from inside Dunkirk’s port – taken on board larger ships, moored to the quayside. In all more than 330,000 Allied soldiers were rescued from Dunkirk. The British government had initially thought little more than 40,000 could be saved. But a combination of the Germans' ‘halt order’ and the good fortune of relative calm in the Channel had made what Churchill called this ‘miracle of deliverance’ possible.

But despite the successful evacuation at Dunkirk, there was no denying that the Germans had won an astonishing victory. One made all the more memorable because it had been won without superior weaponry, but rather, as Professor Adam Tooze puts it, by the ‘uncanny élan of the German troops who displayed truly remarkable fighting capacity in that offensive: the extraordinary marching achievements by the infantry, continuous fighting over days and days and days, essentially without sleep.’ But it was also a victory, as he reminds us, which had also only been made possible by ‘the remarkable incapacity of the British and the French military leaderships to respond with the necessary speed to the German offensive.’

Indeed, once the Germans saw what the British had left behind, they could scarcely believe that victory against such a modern army had been possible. ‘When the Germans actually discover the detritus of the retreating British army at Dunkirk,’ says Professor Tooze, ‘they’re completely overwhelmed by the extraordinary depth of British motorization and the number of trucks the British have just abandoned by the side of the road.’

‘All their vehicles have been left on the beach,’ says Professor Wawro. ‘Most of their field artillery, anti-tank guns, ammunition, fuel stocks, all have been left to the Germans. So it’s going to take an awful long time to build them up, and in fact you’re going to see old, antiquated vehicles running around in the Western Desert because the good stuff was all left behind at Dunkirk.’

And though more than 300,000 soldiers had been saved, there were many British who did not come home in 1940. Around 68,000 of the British Expeditionary Force were killed, wounded or taken prisoner.

Adolf Hitler and the German army had, together, routed the British and conquered France. ‘In some sense, for that brief moment, they found themselves with a kind of tactical battlefield superiority to the British and French,’ says Professor Robert Citino. ‘Now, that did not lead to a happy ending. It lead to a reasonably happy ending in 1940. But a sense of tactical and operational superiority, of course, just simply leads you on to more and more campaigns.’

And Hitler’s next major campaign would be the one that would break him – Operation Barbarossa, the invasion of the Soviet Union. The offensive which many still think – incorrectly – was his biggest gamble of all.

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ⁱ Entry for 3 November 1939 in Franz Halder, The Halder Diaries, Office of Chief of Counsel for War Crimes, Office of Military Government for Germany, 1948
ⁱⁱ Ernest R. May, Strange Victory: Hitler's Conquest of France, I B Tauris, 2000, p. 283
ⁱⁱⁱ Quoted ibid., p. 386
^iv André Beaufre, Le Drame de 1940, Paris, 1965, p.183

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