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Pearl Harbor

December 7, 1941 was a "date which will live in infamy," according to Franklin Delano Roosevelt. The surprise attack on Pearl Harbor by the Japanese led the United States to enter World War II. 


  • On the morning of December 7, 1941, Japan attacked the US naval base at Pearl Harbor, Hawaii.
  • The surprise attack by some 350 Japanese aircraft sunk or badly damaged eighteen US naval vessels, including eight battleships, destroyed or damaged 300 US aircraft, and killed 2,403 men.
  • Across the nation, Americans were stunned, shocked, and angered. The attack turned US public opinion in favor of entering the Second World War. The United States declared war on Japan on December 8, 1941.
  • Japan’s allies, Germany and Italy, declared war on the United States on December 11. The United States responded in kind, and therefore entered World War II.

The Pearl Harbor attack

The Japanese surprise attack on Pearl Harbor began just before 8 a.m. local time Sunday morning, December 7, 1941. For over an hour, in two waves, some 350 Japanese aircraft—having taken off from six aircraft carriers 230 miles north of Oahu—attacked the naval base. Japanese forces wreaked havoc on US naval vessels and on US aircraft on the island’s airfield.start superscript, 1, end superscript In all, 2,403 Americans, including 68 civilians, died in the attack. In comparison, Japan suffered relatively light causalities—it lost only 29 aircraft and a few mini-submarines.squared
Photograph of USS Shaw exploding at Pearl Harbor, December 7, 1941.
The USS Shaw explodes during the attack on Pearl Harbor, December 7, 1941. Image courtesy National Archives.
The American people were shocked, bewildered, surprised, and angered by the attack. On December 8, President Roosevelt addressed a joint session of Congress in the Capitol, his words broadcast on radio to the nation: “Yesterday, December 7, 1941—a date which will live in infamy—the United States of America was suddenly and deliberately attacked by naval and air forces of the Empire of Japan.”cubed
In his address, Roosevelt asked Congress to declare war against Japan, which it did that day. Three days later, Japan’s allies Germany and Italy declared war on the United States, and Congress reciprocated the same day. All previous domestic opposition to US entry into the war ceased. The United States was now immersed in a war it would conduct simultaneously in Europe and the Pacific.

Motive for the attack

The Japanese government decided to attack Pearl Harbor after the United States cut off US oil exports to Japan in the summer of 1941. Japan relied on the United States for eighty percent of its oil, and without US oil supplies its navy would be unable to function. In attacking Pearl Harbor the Japanese hoped to cripple or destroy the US Pacific fleet so that the Japanese navy would have free reign in the Pacific.start superscript, 4, end superscript
Japan was also motivated strategically by ideas of creating an Asian co-prosperity sphere—“Asia for Asians”—in which Japan would take over the Asian colonial holdings of Europe and the United States. With the British, French, and Dutch caught up in the war in Europe, the Japanese believed the European powers would be unable to defend their Asian colonial holdings. Indeed, in the eight hours following the Pearl Harbor attack, Japan also attacked British-held Singapore, Hong Kong, and Malaya, and the US territorial possessions of the Philippines, Guam, and Wake Island.start superscript, 5, end superscript

Forewarnings about the attack

The United States was caught unprepared for the attack on Pearl Harbor, but things might have turned out differently were it not for some bad luck. The United States had broken the Japanese diplomatic code in project “Magic,” and General George Marshall, having been handed a decoded Japanese message on the very day of the attack, had sent word to the US base at Pearl Harbor prior to the assault to “be on the alert.” Atmospheric conditions delayed transmission of Marshall’s message, and it did not arrive until after the attack.start superscript, 6, end superscript
Moreover, the United States had known that a Japanese attack was imminent somewhere in the Pacific, but US military and government personnel had thought the Philippines or some other area of the South Pacific closer to Japan was the likely target. Pearl Harbor was 3,500 miles from Japan and had seemed to the US government and military an unlikely target.start superscript, 7, end superscript
After Pearl Harbor, the United States rapidly mobilized for World War II.

What do you think?

What motives did Japan have in attacking the US naval base at Pearl Harbor?
What was the American response to the Japanese attack?
Do you think the United States would have entered World War II if the Japanese had not bombed Pearl Harbor? Why or why not?

Want to join the conversation?

  • hopper happy style avatar for user Turnercod
    Was the U.S powerful back then and did Japan know.
    (13 votes)
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    • aqualine seed style avatar for user sghlarsen
      Japan was fully aware of America's power. Until American Commodore Matthew C. Perry arrived on Japan's shore in 1853, Japan had been a mostly closed country for the previous 250 years, strictly regulating interactions and trade with foreigners. Perry demanded Japan to open to trade with the West. With the arrival of Perry, Japan realized they were behind the Western world (Europe and America), and from the start of the Meiji (Enlightenment) Era in 1868, Japan began sending people to Europe and America to learn everything they could in order to catch up with the West. Because of its very limited resources, Japan realized it needed natural resources to industrialize and compete with the West. They viewed Europe's power through their massive empires, and they emulated by invading and conquering other Asian countries. The oil embargo placed on Japan by the US threatened Japan's expansion plan for its empire, so while they made diplomatic efforts to get the embargo lifted (on terms to still be allowed to take over desired territories), they prepared for war.
      (33 votes)
  • blobby green style avatar for user lighnkwo4
    does this quote, "a day that will live in infamy", still has meaning to this day? or is it true to this day?
    (8 votes)
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  • duskpin seedling style avatar for user Eden
    Why did japan not think about how powerful the US and not think about the cons
    (9 votes)
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  • leafers tree style avatar for user brickzen
    If Japan had so little resources how did they have the money to be having war with all these countries? wouldn't you have better things to do? where did they get all the resources to build all their aircraft, guns and warships?
    (6 votes)
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    • starky ultimate style avatar for user Zéca
      Japan tried to capture resources from other nations they invaded. At the beginnig of the war, this strategy was working ,because Japan occupied nearby countries, but as the U.S recaptured this countries, Japan started to fall apart, because in a war such as world war 2 resources such as oil are desperately needed to keep communication lines and to maintain wartime production. hope i have helped =)
      (8 votes)
  • piceratops seed style avatar for user desper8enuf
    I have read many other articles on WWII, and some of them have suggested that the US wanted to fight. The US Secretary of war, Henry L. Stimson of the US wrote in his diary, “The question was how we should maneuver them [Japan] into firing the first shot without allowing too much danger to ourselves.” After the Bombing of Pearl Harbor, Stimson affirmed, “my first feeling was of relief… that a crisis had come in a way which would unite all our people.”
    If the US cryptographers had broken the code of Japan (which they had) and had sent a telegram to Pearl Harbor, why was that telegram not sent as urgent. How could the attack have been a "shock" to America? Why did the US want japan to fight against us?
    (6 votes)
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    • female robot grace style avatar for user Sneha Alex
      From my understanding, it was a shock because many Americans didn't fully realize that 1)Japan was a serious threat and 2)the fact that America could be attacked, especially since they technically were not involved in the conflict. As to why some people wanted to fight, they saw the rising threat of fascism and wanted to counter it to protect the US. The reason the US didn't join the war until it was attacked was that people still remembered the atrocities from WWI and didn't want to sacrifice more American lives to protect other countries. After Pearl Harbor, they had a real reason to defend themselves.
      (8 votes)
  • piceratops tree style avatar for user Phuong Phan
    The Japanese had a reason to bomb Pearl Harbor because of the US oil embargo but why do they have to do that? I still can't understand it and there is no way to stop this bombing. The oil embargo is kinda like an act of war. Why though?
    (2 votes)
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  • blobby green style avatar for user 825728
    Was Midway a U.S controlled Island.
    (2 votes)
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  • scuttlebug green style avatar for user hamza khan
    what was the motive for Japan to attack pearl harbor.
    (2 votes)
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    • aqualine tree style avatar for user David Alexander
      Things (as my spouse often reminds me) don't happen for just one reason. They are multidetermined. One of the motives was to strike a blow for a rising empire (Japan) against one that was already well established in the Pacific (the USA). Another was to divert American power until Japan could secure resource-rich territories from the French and Dutch empires in south-east Asia.
      (4 votes)
  • blobby green style avatar for user 825728
    What was a Japanese Internment Camp
    (1 vote)
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    • male robot hal style avatar for user RN
      Japanese-Americans were arrested, and incarcerated after Pearl Harbor, into prison's called internment camps, roughly 120,000 in the US mainland, and about 1800 in Hawaii. 62% of internees were American citizens. People consider this to be racially motivated rather than anything else.
      (4 votes)
  • blobby green style avatar for user Luke Buttry
    Why didn't the US go to war before they were attacked?
    (2 votes)
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