The 10 most consequential events of World War II

This book highlights one of the most significant events of World War II.

The virtue of history is that it affords us perspective—not just the distance that the passage of time occasions but the ability to grasp the importance of events that may have been only dimly understood at the time. What might seem of paramount importance to contemporaries may fade into obscurity as the years go by. But war, or at least great wars, may be an exception, and that is certainly true of the conflict that today we call the Second World War. Suspecting that, I’ve identified the most significant events of the war.

This post was updated on September 9, 2020.

Gaining perspective on the most significant events of World War II

Our view of the most consequential events that took place during the years 1937 to 1945 seems little different from what was understood at the time. Here, in my admittedly unprofessional although informed view, are the ten events that, even today, strike me as having had the greatest consequences for the conduct of World War II.

Month Year Event Description Initiative
July 1937 Japan invades China Opening of the Second Sino-Japanese War in Manchuria Axis
May 1940 Blitzkrieg Nazi Germany invades France and the Low Countries Axis
June 1941 Operation Barbarossa Nazi Germany invades Russia with three million troops. Axis
December 1941 Pearl Harbor Japan launches war on USA in surprise dawn attack Axis
December 1941 Battle of SingaporeJapan launches war on British Empire Axis
June 1942 Battle of Midway USA defeats Japanese Navy Allies
February 1943 Battle of Stalingrad Field Marshal Paulus surrenders to USSR Allies
May 1943 Battle of the Atlantic British turn the tide against Nazi Germany’s U-Boats Allies
June 1944 Operation Overlord USA and UK invade Normandy Allies
August 1945 Hiroshima & Nagasaki USA drops atomic bombs Allies

Viewed from the perspective of the year 2020, there is remarkable symmetry in this picture. During the war’s first four years, the Axis nations held the initiative. In the following four years, the initiative moved to the Allies. Focusing on one battle, or one theater of the war, can obscure that reality. Some might quibble about the choices I’ve made. Perhaps some other battle might qualify as one of the most significant events of World War II. But the Big Picture is clear.

Revisionist views of the war’s turning points

Admittedly, the chart above reflects the consensus view of historians today. However, there are revisionist views about many aspects of these events.

  • For example, it can be plausibly argued that the Soviet Union’s successful defense of Moscow in December 1941 is a more significant turning point in the European war than the victory at Stalingrad. It was then, rather than more than a year later toward the south, that Nazi Germany’s invasion of the USSR ground to a halt. Hitler had made the same catastrophic decision as Napoleon Bonaparte a century and a half earlier—and with the same predictable results.
  • Similarly, not all military historians today agree that the Battle of Midway was the turning point in the Pacific. That assertion reflects the naval strategy advanced by Admiral Chester Nimitz. Some observers argue that the Battle of Guadacanal months later was more decisive, as General Douglas MacArthur might have insisted. The two co-equal commanders in the Pacific war were rivals throughout and continue to have their champions.

Critical advances in science and technology

However, it’s difficult to appreciate fully the Big Picture without noting the advances in science and technology and in industrial production that loom large in the story of the war, too. Any full account of World War II is incomplete with knowledge of the development of radar and the atomic bomb, and the success in breaking the German Enigma, Japanese Purple, and other significant Axis codes and ciphers. Equally important were the breakthroughs in industrial organization that enabled the United States to produce hundreds of thousands of airplanes, ships, and tanks in record time.

Political events had vast consequences, too

All the ten events I’ve listed above involve military conflict. Some might plausibly argue that several political events should be given equal standing.

However, it’s challenging at best to compare the consequences of these undoubtedly important events with campaigns and battles that together claimed many millions of lives.

Hitler’s strategic blunders in World War II

In the conventional view Adolf Hitler receives middling marks as a military strategist. Historians tend to acknowledge at least some of his poor decisions but point to the successes he engineered early in the war through the Blitzkrieg strategy he adopted so enthusiastically. However, it can be plausibly argued that, in the final analysis, Nazi Germany lost the war because of Hitler’s strategic blunders. Here are just a few that most knowledgeable observers agree were just that:

  • Operation Barbarossa was originally scheduled for May 15, 1941. Hitler elected instead to shift some of the forces earmarked for the invasion to the Balkans, where his ally Benito Mussolini had foundered in his invasion of Albania and Greece. The decision cost more than a month and, when the German advance in Russia slowed in the fall, ensured that the Nazi forces would encounter what Russians call “General Winter.”
  • When planning Operation Barbarossa, Hitler’s generals implored him to mass their considerable forces in a drive directly toward Moscow. Instead, Hitler insisted on a three-pronged invasion, heading north toward Leningrad, at Moscow in the center, and south toward the resource-rich Caucasus. The generals were almost certainly right that overwhelming German striking power would have permitted them to capture Moscow in 1941—and possibly then end the war with victory over the Soviet Union. In fact, most military observers argue that Hitler’s later decision merely to divert the lion’s share of his tank armies from the campaign against Moscow to the battles to the north and south was alone enough to prevent the Nazis from taking Moscow.
  • Following Pearl Harbor, Franklin Roosevelt asked Congress for a declaration of war against Japan. He pointedly did not propose to go to war with Nazi Germany, which in fact he regarded as the main enemy. Hitler played into his hands on December 11, 1941, when he unaccountably declared war on the USA. While it seems likely the two countries would eventually have faced off, Hitler’s surprising decision to support his Japanese ally permitted Roosevelt to do what he had hoped to do for more than a year: accede to Winston Churchill’s plea to place a higher priority on the war in Europe than that in the Pacific.
  • Military strategy is by no means all about battles. At its foundation, strategy rests on the availability and allocation of resources, including both fighting men and women, the tools they need to prosecute war, and the natural resources necessary to manufacture them. In allocating scarce resources, some argue, Hitler made decisions that cost his country dearly. For instance, Admiral Karl Dönitz, commander of Germany’s submarine forces early in the war, had begged for German factories to produce more U-boats. Had Hitler given him what he wanted, it’s entirely possible, even likely, that Germany would have won the Battle of the Atlantic and ended the war in the West in 1941 or 42. Hitler made a similarly bad decision not to direct the necessary resources for Willy Messerschmitt to expand production of the ME-109 (or Bf 109) jet fighter. The plane first saw service in Spain in 1937. Had the Germans produced it in numbers, it seems highly unlikely the outnumbered British could have prevailed in the Battle of Britain, as the ME-109 significantly outclassed the very best British fighter, the Spitfire.

Books to read

Over the years, especially during the past decade, I’ve read a great deal about World War II. If you’re interested in exploring any aspect of this world-shaking contest, you might turn to either of the following posts. Together, these articles survey hundreds of books that I found rewarding. (Those I didn’t enjoy either fell by the wayside, unfinished, or I simply didn’t include their reviews in these lists.)

However, if some other topic or genre strikes your fancy, you can always find my most popular reviews, and the most recent ones, plus a guide to this whole site, on the Home Page.

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