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The 10 most consequential events of World War II

This book highlights one of the most significant events of World War II.
China played a huge role in WWII.

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 was arguably the biggest turning-point in world history. Suspecting that, I’ve identified the ten most significant events of World War II.


This post was updated on February 3, 2021.

Estimated reading time: 6 minutes


Hitler's invasion of the USSR was one of the most significant events of WWII.

This map depicts Operation Barbarossa, the German invasion of the USSR that began on June 22, 1941. It depicts the breadth and complexity of the largest military operation in world history. Note that every one of the tiny rectangles on this map represents hundreds of thousands of soldiers. Image credit: Wikipedia

Gaining perspective on the biggest turning-point in world history

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.

MonthYearEventDescriptionInitiative
July1937Japan invades ChinaOpening of the Second Sino-Japanese War in ManchuriaAxis
May1940BlitzkriegNazi Germany invades France and the Low CountriesAxis
June1941Operation BarbarossaNazi Germany invades Russia with three million troopsAxis
December1941Pearl HarborJapan launches war on USA in surprise dawn attackAxis
December1941Battle of SingaporeJapan launches war on British EmpireAxis
June1942Battle of MidwayUSA defeats Japanese NavyAllies
February1943Battle of StalingradField Marshal Paulus surrenders to USSRAllies
May1943Battle of the AtlanticBritish turn the tide against Nazi Germany’s U-BoatsAllies
June1944Operation OverlordUSA and UK invade NormandyAllies
August1945Hiroshima & NagasakiUSA drops atomic bombsAllies

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, or one that I’ve picked might seem of less than strategic importance. 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. Yet others might plausibly contend that the die was cast for Japan’s defeat as soon as her navy attacked Pearl Harbor. As Admiral Yamamoto himself fully understood, there was no chance that the Japanese Empire could prevail in the long war with the United States that the attack itself ensured.
  • The conventional view is that the Japanese Empire consented to unconditional surrender because of the two nuclear weapons dropped on Hiroshima and Nagasaki, and there is of course no doubt that was a meaningful factor in the decision. However, many have argued persuasively that the declaration of war on Japan by the Soviet Union on August 8, 1945, weighed even more heavily on Emperor Hirohito and his Cabinet.

Critical advances in science and technology

The British success in breaking the German Enigma codes was one of the most significant events of WWII.

This early computer developed by British mathematician Alan Turing and his colleagues at Bletchley Park was instrumental in deciphering the “unbreakable” German Enigma codes. Image credit: Bletchley Park

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 without knowledge of the development of radar and the atomic bomb, and the success in breaking the German Enigma system and the Japanese codes dubbed Magic and Purple by the Allies, as well as other significant Axis codes and ciphers. Equally, perhaps even more 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. It’s those blood-soaked episodes that I believe are the ten most consequential events of World War II.

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 scores 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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