Not only is Roberts not a wishy-washy historian — no "up to a certain extent"-type weasel words for him — he is also unafraid to inject a certain wry humour into the work, which makes it all the more readable. Recounting the lamentable failure of the French High Command during the spring of 1940, he remarks that its generals allowed their headquarters to be a considerable distance away from the front line, adding: "Even in the land of chateaux this was taking chateau-generalship ludicrously far." The strongest sections of the book — not surprisingly given Roberts's previous work — are those about the Western Front. In particular, the way Roberts charts the shifting relationship between the Western Allies throughout the course of the war is exemplary.

More controversial is the lengthy conclusion Roberts appends to the book. His central thesis is that Hitler lost the war because, as he puts it simply, "he was a Nazi". Roberts thus believes that Hitler's ideological beliefs led the Germans to defeat. It is an argument that is certainly open to debate. After all, ideology doesn't necessarily mean that a military adventure is doomed — indeed, the possession of an absolute belief system was one of the reasons that a variety of conquerors throughout history were successful. And during the Second World War, as Roberts acknowledges elsewhere in the book, things could have gone very differently. In the spring of 1940, for instance, more than 300,000 British soldiers might not have escaped from Dunkirk and there was a possibility — if Churchill had not been Prime Minister — that Britain might have sued for some kind of compromise peace. 

Equally, Roberts is in danger of underestimating the delicate balance that existed in the war between the Nazis and the Soviet Union in the autumn of 1941. A persuasive argument can be made, for example, that the most crucial moment of the 20th century occurred on 16 October, 1941, when Stalin decided not to flee Moscow in the face of the German advance. If Stalin had left the Soviet capital, then Red Army resistance might well have swiftly collapsed, with the Nazis forcing the Soviet Union shortly afterwards to make a humiliating peace. And this, remember, was before the Americans had entered the conflict. Hitler would thus have most likely won the war. And he would have remained, of course, very much a Nazi — a successful one.

But none of this is to take away from the power of Storm of War. Indeed, part of the joy of this book is that one can argue with Roberts's point of view — not least because he so clearly expresses it. And in terms of narrative history the book is an undoubted triumph. 

This, simply, is the best one volume history of the Second World War currently available.