LAURENCE REES: Was there ever really any prospect of the Germans invading Britain in 1940?

ADAM TOOZE: No. I do think one has to understand the timeframes here. They hadn’t started thinking about a war with Britain, let alone an invasion, until May 1938. The naval armaments programme doesn’t get into gear until January 1939. For the preceding five years Britain had been outspending Germany on the navy so the already enormous gap between the German navy and the British navy in 1933 had not been shrinking but growing larger every year. So when they then also go on to lose the vast majority of their modern naval forces in the Norwegian debacle which, from a German naval point of view, is a catastrophe, they essentially do not have a surface navy with which to protect an invasion in the summer of 1940. I believe they had three cruisers and four destroyers. Two of the cruisers are light cruisers, and so the preponderance of the home fleet is absolute, which basically makes any invasion attempt a huge gamble, because if the British decide to launch a suicidal charge through the Channel they can cut the supply lines and isolate the German army and that will be the end of that.

Added to which the Germans don’t have the wherewithal to establish air superiority over the beaches. They can obviously inflict defeats on the RAF but they can’t establish blanket air superiority for any long period of time. And then crucially, of course, their ground forces, though they work extremely well in the narrow confines of northern France and Belgium and so on, are simply not equipped to sustain the logistical problems of a cross-Channel invasion. This is an army for which the majority of its forces rely on horses. So one has to imagine the Dardanelles, I think, as the sort of scene that one would have seen on the Kent beaches in 1940 or 1941, if the Germans had gone ahead with an invasion. Hopeless ships lumbered with writhing masses of horses with no means of escape from the bridgehead because the Germans wouldn’t have been able to put significant amounts of armour ashore, let alone supply it with fuel to achieve any kind of breakthrough. And we know how much the British and the Americans struggled with this in 1944 despite their overwhelming logistical superiority. And the Germans just don’t have anything remotely like that in place in the summer of 1940.

LAURENCE REES: So if there is no realistic chance of the Germans invading Britain in 1940 why is it such a huge myth that Churchill saved us from a German invasion - Operation Sealion - which was cancelled only after the Battle of Britain?

ADAM TOOZE: It’s significant that when Cripps is sent to Moscow to talk with Stalin, and to enrol Stalin in the war against Hitler, Stalin readily admits that the overturning of the world order to which he’d committed himself in the autumn of 1939 had gone rather farther and rather more quickly than he’d anticipated. He says to the British, look, don’t panic, which means we’re not coming to your aid, because this war isn’t lost yet and you haven’t lost it and the Germans haven’t defeated you.

So I do think one has to understand that sense on the British part, as part of a fairly deliberately cultivated propaganda mood which is used to solidify the British position domestically and Churchill’s position in particular, to criticise the outgoing Chamberlain regime and to separate oneself from that, and of course also to establish the basis for Britain’s increasingly clamorous demands on the United States, which are absolutely crucial to the continuation of the British war effort.

LAURENCE REES: So in essence Churchill’s hyping the whole thing up?

ADAM TOOZE: Yes, I think that’s fair to say. I mean, it’s not surprising, of course, after having suffered this catastrophic defeat in strategic terms and having lost one’s major continental allies, both Poland and France, not to mention the other smaller states, in a matter of weeks. There’s no question that this is Britain’s largest strategic disaster, possibly ever in military history. So one can excuse the panic. But seen in the cold light of the data that we have available to us now, and understanding the limitations of the German war machine from the inside as we’re able to do now, it does all seem grotesquely exaggerated.

LAURENCE REES: And it also makes more understandable Hitler’s statement in the summer of 1940, when he says that the only way to defeat Great Britain is to invade the Soviet Union. Since what he’s also saying - in effect - is that realistically we’ve got no method of invading Great Britain. And actually this all makes a kind of sense doesn’t it?

ADAM TOOZE: Yes, absolutely it does. The other thing to understand, of course, is that whereas the Luftwaffe and the navy fail, the army has just delivered this extraordinary, world changing, quite unexpected victory. So you basically have a choice of two weapons that have proved frail and inadequate and one that has proved unparalleled in its effectiveness. Furthermore, of course, the Germans live with the memory of having already defeated Russia once in the 20th Century, and surely an army which can inflict that kind of defeat on France will make rather light work of what they believe to be a fragile regime in the East. And if you put those two things together, even if Hitler were not the ideologically driven, strategic thinker that he is, you would still be able to produce a fairly convincing rationale for an invasion in the East.

LAURENCE REES: And, of course, that’s the act that, paradoxically, some people today say proves he’s mad.

ADAM TOOZE: Yes.

LAURENCE REES: Here is Hitler doing this conceivably mad thing but actually in the context of the time it made complete sense?

ADAM TOOZE: Well, until they began to think hard about the operational logic of the Barbarossa invasion and then they discover, as they actually also do in 1918, that defeating Russia is a complex business. You can, indeed, inflict military defeats on the Russians, but whether you can actually comprehensively defeat the Russian state, which is something that they actually also failed to do in 1918, is a far more open question. Fundamentally, when they start to think hard about the Barbarossa Operation they realise that they have to inflict a really all encompassing military defeat, as they had just done on France, on the Red Army, but within a limitless geographical space. And hence the sort of totemic significance of the Dnieper/Dvina River Line where all of the operational thinking has essentially to achieve its ultimate outcome within that 500 kilometre depth of the first wave of the invasion. Beyond that, frankly, the German plans quite rapidly begin to lose their coherence. Which is also what Ludendorff and Hindenburg experienced in 1918, that you can win in western Russia but whether that really allows you to establish all encompassing dominance over the entire expanse of Russia is a completely different question, and at that point politics comes into the equation in a very uncomfortable way.