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To cut America off at the knees, per se, and decimate their naval strength so they would be unable to defend the Pacific, Japan decided to execute a surprise attack on America’s largest base in the Pacific—Pearl Harbor.
Over the course of history, international alliances and the geopolitical landscape inevitably change. Relationships can be strengthened, tested, evolved and destroyed in the course of a single generation.
As of today, Japan and the United States have an excellent relationship; more specifically the United States is Japan’s second-largest trading partner, and they are strong allies. A century ago, a similarly close kinship existed, but in the middle of the 20th century, Japan was America’s enemy in the deadliest war the world has ever seen.

On December 7, 1941, the Japanese military executed a surprise attack on Pearl Harbor, the main Pacific base of the United States Navy. More than 2,000 soldiers were killed and the level of destruction was on a scale that had not occurred on American soil in generations.
So, this leaves one obvious question…. why did Japan attack Pearl Harbor?
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Japan In The Early 20th Century
To understand this surprise attack—which drew America into WWII—one must look at the history and dynamic progression of Japan in the early 20th century. The Meiji Era of Japanese history began in 1868 and was marked by political ambitions and the desire to be a powerful force in a rapidly industrializing world. In an effort to escape their feudalistic traditions and instead be recognized as a world power, Japan opened itself up to the social, political, industrial and cultural influence of Western nations—a massive shift in their approach towards the rest of the world.
In the middle of the Meiji period, Japan was victorious in two different wars, the first Sino-Japanese War (1894-1895) and the Russo-Japanese War (1904-1905). This established the country as a legitimate military power, and also made them an ideal member of the Allied forces in WWI. While their participation in WWI was limited to the Pacific and certain parts of China, they emerged from that conflict on the winning side. As a result, Japan was able to get a strong foothold in terms of trade and influence across Europe and Asia.
The beginning of WWI marked the end of the Meiji period, and a subsequent shift in ideology for the Japanese. They became more liberally minded, and for 15 years of the Taisho period, Japan began steadily moving towards a democracy. Unfortunately, like the rest of the world, Japan was slammed by the Great Depression, and increasing pressure to boost the economy led to a rise of military-minded leaders, giving way to the Showa period, in which Japan embraced totalitarianism, nationalism and fascism.
As Japan watched the US and other powers increase their stake in Asian markets, the island nation decided to make moves into China, specifically an area known as Manchuria, in 1937. Although the entire war was bloody, the Nanjing Massacre stands out as particularly horrific, an event that largely shifted international opinions regarding Japan. The United States, in an effort to curb Japan’s growing and brutal ambitions, imposed economic sanctions and provided support to Japan’s enemies. By 1940, Japan had allied itself with Germany and Italy, the fascist Axis of Evil in the world.
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WWII And Pearl Harbor
Although the drums of war had been beating in Europe for years, and the official beginning of WWII was 1939, it took two years for the United States to enter the global fray. When the war broke out, America was frankly neither interested or capable of joining the conflict. The vast majority of Americans were against the idea of entering the war, and the government decided that they would not take direct action unless threatened or attacked.
Perhaps more importantly, America was benefiting economically from the war as a result of their production and sale of equipment and arms to the Europeans. They were not spending that money to directly boost their own military might, nor the numbers in their army. America was militarily behind the warring European nations and had a relatively small military in comparison to Germany and other combatants. Therefore, from September of 1939 until December of 1941, the United States remained safely sheltered by two oceans, remaining “neutral”.
The Axis countries knew this, and were glad to not have America join the war, given the side they would join. A key piece of their global strategy, however, included the Pacific, and Japan had its eyes on a number of territories in the Asia-Pacific region. The United States had a number of territories and naval bases in this area, so Japanese aggression would inevitably butt up against American interests. This meant that conflict with America was unavoidable, and they would eventually enter the war.
To cut America off at the knees, per se, and decimate their naval strength so they would be unable to defend the Pacific, Japan decided to execute a surprise attack on America’s largest base in the Pacific—Pearl Harbor. On the morning of December 7, 1941, more than 350 Japanese aircraft attacked the battleships, cruisers, destroyers and infrastructure. More than 2,400 people were killed in the attack, and it initially looked like a complete success for Japan. Four of the battleships were sunk, and the other four were damaged. However, six of them were ultimately returned to service, and none of the American aircraft carriers were present at Pearl Harbor.

What may have first seemed liked a devastating pre-emptive blow to the American Pacific fleet, was actually an alarm clock for the American war machine. Prior to the attack, America had no interest in joining the war, but Pearl Harbor unified and motivated the country. Patriotism swept through the United States and hundreds of thousands of men signed up to fight. Within 4 days, America had joined the war with massive support of the country’s citizens. The rest, as they say, is history.
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A Final Word
Looking back, we primarily view Pearl Harbor as the beginning of America’s story in WWII, but the truth of the matter is that Japan could have been successful. If the aircraft carriers had been present, if the repair facilities had been destroyed, or if fewer of the battleships had been sunk, Japan’s Pacific dominance may have remained unchallenged, American morale could have been destroyed, and the entire course of history may have changed!
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References (click to expand)
- The Complicated Lead Up to Pearl Harbor. The National Air and Space Museum of the Smithsonian Institution
- Eyewitness to a "Day of Infamy": Commemorating Pearl Harbor | National Museum of American History - americanhistory.si.edu
- Modern History. The Internet History Sourcebooks Project
- RP Harbor. A PEARL HARBOR FACT SHEET. The United States Census Bureau
- Kahn, D. (1991). The Intelligence Failure of Pearl Harbor. Foreign Affairs. JSTOR.