In the London library in St. James’s Square, the books on World War II are somewhat archaically shelved under the classification “European War (II).” This was because when the Great War broke out in 1914, the librarian gave it the designation “European War.” This was changed to “European War (I)” in 1939 when it became clear there was going to be another one, and the Library still hasn’t gotten around to adopting the generally accepted modern titles for either war. It is the contention of Victor Davis Hanson’s profoundly-researched, extraordinarily well-written, and insightful book that if Hitler had managed to keep the struggle as a European War (II) rather than allowing it to career out into a World War II, then the Nazis would have undoubtedly won.

As the use of the plural in The Second World Wars implies, Hanson, a senior fellow at the Hoover Institution and the author of 21 books, mainly on military history, sees the conflict that began with Japan’s invasion of China in 1931 and ended with Japan’s surrender to the Allies in 1945 as a series of wars that were surprisingly discrete, at least until 1941 when hubristic (and almost insane) German and Japanese overreach brought them all together into one great struggle that the Axis powers had no possibility of winning. In his exposition of this thesis, displaying a depth of knowledge of the period that is often simply astounding, Hanson has written what I consider to be the most important single-volume explanation of World War II since Richard Overy’s Why the Allies Won (1996)—that is, for a generation.

Yet it is not a history in the conventional sense. It doesn’t tell you what happened next, so it requires more than passing knowledge of the conflict to make sense of it. Approached thematically, the war(s) are subjected to a penetrating but non-chronological analysis. This is therefore a history, rather than a narrative, of World War II; for the latter, one might profitably go to books like Max Hastings’s All Hell Let Loose (2011) or Antony Beevor’s The Second World War (2012). What Hanson does is explain, as his subtitle puts it, how the first global conflict was fought and won. He splits his themes into the self-contained areas of “Ideas,” “Air,” “Water,” “Earth,” “Fire,” “People,” and “Ends,” each with its own self-contained subsections.

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As one might expect from a military historian who has written extensively about the Peloponnesian War and other wars of the ancient world, Hanson supports his theories with a rich panoply of examples drawn from many other historical periods well beyond the 20th century: Themistocles and Thucydides make appearances, for instance, always to good effect and useful elucidation. So while acknowledging that the Second World Wars were uniquely destructive and costly in terms of human life, Hanson anchors them into other conflicts. “Britain’s position was worse than that of the beleaguered Romans after Cannae or the Athenians on the eve of Salamis,” he says of the period immediately after the Dunkirk evacuation, for example, “as it was vastly outnumbered, with most of its allies vanquished, and few others willing to come into the fray…. Without a formal wartime alliance with the United States, and with his European partners all defeated, [Winston] Churchill nevertheless insisted on continuing the war without negotiations with the Axis powers.”

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Hanson is acutely attuned to the influence of Churchill and the opposition he faced even during the Blitz and the Battle of Britain. He quotes what he rightly calls “a backhanded compliment that illustrated the contempt of the British elite,” when on the very evening of Churchill’s great speech about the Royal Air Force—the one that featured the line “Never in the field of human conflict was so much owed by so many to so few”—the daughter of former Prime Minister David Lloyd George met with the Soviet Ambassador to the United Kingdom Ivan Maisky. Megan Lloyd George was a Liberal M.P., and told Maisky of Churchill, doubtless in that morally superior tone that she often adopted (and at which Liberals excel),

What always appealed to him most was war. He studied the wars of the past and contemplated the wars of the future. He always imagined himself a military leader, destroying armies, sweeping through Europe, overthrowing his enemies, or putting them to flight. Military terms were always on his lips, and his head was always full of military plans and projects. I am sure that today he is wholly absorbed and intoxicated by the war.

She was presumably not so censorious of Churchill when Allied forces were genuinely destroying armies and sweeping through Europe after D-Day, putting to an end the regime of Adolf Hitler, the man whom her father had lauded as “one of the greatest of the many great men I have met.” By then it was just as well that Churchill’s head was always full of military plans and projects.

Hanson is similarly impressive on the morality of the combined bomber offensive, which was crucial to victory over the Nazis, but which by the 1960s had come to be criticized by a new generation of what we might today call “snowflakes.” As one might expect from the brilliant polemicist of conservative magazines and newspapers, Hanson is unremittingly caustic on the proponents of what he calls a “new postmodern idea of ‘proportionality’ [that] arose in the West (but certainly not in Russia or China), suggesting that in war the defender should seek to pay back aggressors with no more lethal force than was originally used against it.” As he points out, in one of the hundreds of pertinent statistics in this book, “Few note that the losing Axis powers inflicted 80 percent of the fatalities of World War II—the vast majority of them unarmed civilians.” There is a moral core to this book that is as important and powerful as the military insights it gives.

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For Hanson does not believe the war was necessary, and he argues that with more intestinal fortitude—with some more Churchills and fewer Chamberlains—it might have been avoided. He soundly names the disastrous trifecta of “British appeasement, American isolationism, and Russian collaboration” as the key factors that allowed Hitler, Mussolini, and the Tokyo militarists to seize their chance and unleash unprecedented destruction upon the world. The lessons for the modern day are obvious and ought to be heeded before the consequences visit families today in the way that they visited Hanson’s own.

We learn in the book that Hanson’s father flew three dozen missions over Japan in a B-29, a paternal cousin died on Sugar Loaf Hill at Okinawa, and another cousin ferried military aid to the Russians in Persia. Meanwhile, one maternal cousin fought in George Patton’s Third Army, another contracted dengue fever fighting in the Pacific, while another was killed serving with the Seventh Army in France in late 1944. If anyone has the right to despise what he calls “self-critical, affluent and leisured citizens of the democracies” who criticize their parents’ way of waging war, it is the author.

Hanson’s depiction of what was in 1939 essentially a series of localized border conflicts that got wildly out of control, and which by 1943 meant that the Axis Powers had no hope of victory, is sustained with a welter of scholarly supporting evidence. “By 1943,” he argues, “the German army had devolved from an aggressive and competent regional offensive force into an outmanned and out-supplied global occupation army that could no longer win the ground war it had started.” The German infantryman of World War II recalled in his training and professionalism the Spartan hoplite of nearly two and a half millennia earlier, and Hanson does not deny that at its height, the Wehrmacht was “the best fighting force in the history of land warfare.”

Yet it was never going to be enough once the Führer had unleashed Operation Barbarossa.