LAURENCE REES: So we’re dealing with quite an extraordinary figure here, in Adolf Hitler. And it is wrong to suppose that he sees this war, at any stage, as merely about recovering territory lost at Versailles. He always has an epic vision in mind, and that epic vision must involve an enormous conflict?

SIR IAN KERSHAW: Yes, that’s right, and the vision is one which came close to being put into practice in 1941 with the attack on the Soviet Union. That was Hitler’s war, that was the war that he’d always wanted to fight, this war to acquire living space. But going back to the initial question you pose then, that living space that he was acquiring there (and the equivalent the Japanese were expanding their own territory in - in the Far East) that from the point of view not just of Hitler, under his immediate supporters but of others too, was land which would provide for Germany for the infinite future.

So it was settlement land – it was land which would provide the food that Germany needed, it would take it outside the vagaries of the international markets, and therefore there was a sort of crude economic basis to this power politics of acquisition of new territory. And the racist idea and the acquisition of new territory and the economic notion went hand in hand, they were one and the same thing.

LAURENCE REES: So how decisive a figure was this individual, Adolf Hitler, in the origins of this war?

SIR IAN KERSHAW: Well he was, of course, crucial in this. If you pose the counterfactual question, would there have been general European war by 1939 without Hitler, with another nationalist German leader? Quite conceivably the answer is 'No'. There would have been pressure within Germany to regain territories that had been taken away at Versailles and there would probably have been some adjustment to that, those territorial losses as time went on and so on.

But by 1938-39 quite considerable sections of the German elites – the military elite, the elites in the higher ranks of the Foreign Office and so on – and not just that but even within the Nazi Party itself were getting cold feet about the prospects of a war which they thought Germany might well lose. And no less a figure than Hermann Goering, the second man in Germany, said in August 1939 to Hitler, “Mein Fuehrer, must we always go for broke?” And he wanted to back down really from that, seek some sort of negotiated way out of the crisis building up over Poland. And Hitler’s reply was a characteristic one, “Goering, you know all my life I’ve gone for broke.”

So, without that figure history would have been different. But, of course, it would also be a mistake to presume that this was Hitler and nobody else, that we know the forces who were pushing for this. And for a long time we’ve said already that Hitler was seen as an arch-nationalist, a very radical nationalist, but he was also an arch-militarist, and that militarism stood him in very good stead within Germany, as the very strong forces that backed the Wehrmacht, the German armed forces, all supported the build-up of this: the recovery of a strong Germany, the recovery of German defences, the huge expenditure on building up this colossal army and armed forces, Luftwaffe as well, and Navy. And so all these forces were pushing for what? For some sort of expansion, acquiring German dominance in Central Europe and so on, but avoiding a war already by the end of the 1930s, against forces that they thought they might well lose against. So in that sense Hitler’s own personality, at crucial junctures, was decisive in pushing for this war when other people would have backed off.