LAURENCE REES: Let's talk about D Day. Why did it take the Allies so long to organise D-Day? Why did it take until 1944 for it to happen? And if it was going to take that long why did Churchill and Roosevelt lead Stalin to believe that it would happen earlier?

RICHARD OVERY: I don’t think that Churchill and Roosevelt had much choice really, but to try and keep Stalin on board by making it clear that they would do everything they could, and hinting or even saying this might involve a second front at quite an early stage in the war.

LAURENCE REES: Well, they were promising it, weren’t they?

RICHARD OVERY: I know, but this also keeps him on board, they hope.

LAURENCE REES: So you think it’s just that they are stringing him along?

RICHARD OVERY: I don’t think they’re just stringing him along, but I think there are too many uncertainties. For the Soviet war effort there are no uncertainties, there’s only one thing you can do. You have millions of Germans there and you’ve got millions of Russians and you keep banging away at each other; it’s a simplified strategy. For the British and Americans it’s not a simple strategy. The British for their own, mainly imperial, reasons are absolutely dead set on keeping the Mediterranean and the Middle East in their hands, and the Americans find that fighting the Japanese is much harder than they expected, so the huge numbers of landing craft, naval vessels and many of the people with real operational experience in combined operations are in the Pacific.

You can move a few of them around but as it becomes clear that the Japanese are going to fight suicidally for every atoll then the nature of that war changes, and the Americans have got to think hard about balancing up what they want to do there with what they want to do in Europe. None of these things were predictable in 1942 when they start talking to Stalin, and I think in the end they find themselves having to do the only thing that they can do. I know we can argue about Italy and whether it was a sensible decision or not, and probably it wasn’t in the end, but again there was a lot of pressure in both Britain and the United States to get at the Axis enemy. But there was no way of getting at the Axis enemy decisively in 1942 and 1943, and I think that what they finally do cleaning up North Africa and clearing the Mediterranean, knocking Italy out of the war, contributes quite a lot actually to improving the strategic profile of the Allies. Most importantly, it gives them experience, so you’ve got officers who understand what to do and have had some experience of combined operations and landing on beaches.

LAURENCE REES: But you said that you agree that Italy was probably not a good idea?

RICHARD OVERY: Well, you can argue it a number of ways. It’s difficult to see whether Italy would have maintained belligerency for much longer anyway. Almost certainly not if the revolt against Mussolini happened, and that would have left the Germans with a bit of a quandary really, because if they had to station troops on the whole of the peninsula they’re going to be soaking up 20 divisions. They’re going to be expecting, perhaps, an Anglo-American landing while the British and Americans can use largely air power and sea power to hold onto the Mediterranean.

LAURENCE REES: And, crucially, much of the countryside in Italy favours the defenders.

RICHARD OVERY: Absolutely, it does.

LAURENCE REES: So once the Allies were in Italy, there were people thinking, 'why on earth am I fighting in these mountains?'

RICHARD OVERY: You can certainly argue that. You might argue, of course, that it gives people experience and speeds up the elimination of Mussolini.

LAURENCE REES: The fact that the Allies gained valuable battlefield experience in Italy and North Africa is something that at least one distinguished American military historian has already put to me. 

RICHARD OVERY: American divisions in Tunisia were taking 25 percent psychiatric casualties, people who just didn’t want to fight. They still had quite a high level of psychiatric casualty on D-Day, but by then they’d had 15 months of blooding. And British troops had been sitting in camps bored for 2 years and it’s not at all clear they could have got across the Channel and done to the Germans what they eventually do to the Germans. They also haven’t built up the air power, which, of course, is the key thing that makes D Day possible. That was going to take some time to build up to an adequate level.

So there were a lot of arguments. They have to mount an operation [on D Day] that succeeds as to mount an operation that fails would be disastrous. Disastrous to the home populations, disastrous to the armed forces and disastrous to Stalin, so it’s absolutely got to succeed. And we know of course that there are the Americans, Canadians and the British bottled up in Normandy for the first four or five weeks of the campaign, but even with fairly limited resources and no air power the Germans were a formidable enemy. So we can’t take it for granted. It has to succeed, and that’s why it’s postponed for so long.