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Pearl Harbor
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The Day that Lived in Infamy
Declaration of War
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Pearl Harbor
Smoke billows out from U.S. ships hit during the Japanese air attack on Pearl Harbor.

The Japanese attack on the US Naval Base at Pearl Harbor in Hawaii was the event that directly led to US involvement in the Second World War. The attack that started at 7.55 on Sunday morning December 7, 1941, led to the deaths of 2,400 Americans, with another 1,178 injured. Within two hours, five battleships had been sunk, and another 16 damaged. 188 aircraft were destroyed. But the main target - 3 US aircraft carriers - usually stationed at Pearl Harbor, but assigned elsewhere on that day, escaped damage.

Japan becomes militant

At the beginning of the 20th century, Japan was pro-western. Western music and art was popular. Japan was also one of the allies fighting against Germany during the First World War. But the Great Depression of the early 1930s changed the mood in Japan. As was the case in Germany, the crisis forced moderates out of government and militants took over who were anti-Western and wanted military solutions to Japan’s problems. In 1931, Japan occupied Manchuria in northern China. As Japanese aggression increased in the next decade, its relations with the US deteriorated. The Japanese declared war on China in May 1937. This soured relations even further, especially because of atrocities committed by the Japanese army.

The road from dependency to war

Japan had always relied on the United States to supply many natural and industrial resources such as fuel. These materials are rare in Japan. But the United States was deeply worried by Japanese aggression. As a response, it ended its commercial treaty with Japan in January 1940. In July of that year it decided to block shipments of scrap iron and aviation fuel to Japan. This made it more difficult for Japan to continue its war efforts. It turned its focus to the Asian colonies of countries like France and the Netherlands for its materials. With Europe at war, these colonies could easily be defeated by military means. When Japan signed a treaty (the Tripartite Pact) to cooperate with Germany and Italy in September of 1940, war seemed to be inevitable. It had become a member of the Axis alliance fighting against the Allies in the European War. But the US still took the position that it should do everything to stay out of the conflict. The attack on Pearl Harbor a few months later changed the US position dramatically. The United States declared war the next day.
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Photo Credit: USHMM, courtesy of National Archives and Records Administration, College Park.
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This day in history
Today: 14 December 2017
Then: 11 December 1941

Germany and Italy declare war on the United States; the U.S. respond in kind.

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