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Pearl Harbor: Photos and Facts from the Infamous WWII Attack

The surprise Japanese assault inflicted heavy losses but failed to strike a decisive blow.

On the morning of December 7, 1941, Japan launched a sneak attack on the U.S. Pacific Fleet’s base at Pearl Harbor in Hawaii, as part of a plan to eliminate any potential challenge to Japanese conquests in Asia. The attack compelled the United States to enter World War II as a combatant, and to wage a costly, bloody struggle to defeat the Japanese empire.

The events set in motion by the attack also led to the United States becoming a global superpower. As Peter Harris, an assistant professor of political science at Colorado State University, wrote in 2017, the attack dramatically altered U.S. foreign relations, “sidelining isolationism as a powerful force in domestic politics and making overseas engagement the accepted norm.”

Here are some key facts about the attack.

Why Japan Attacked Pearl Harbor

  • The Japanese plan to attack Pearl Harbor was devised by Admiral Isoroku Yamamoto, a former student at Harvard University who had served as Japan’s naval attaché in Washington. Yamamoto knew that the United States had far greater resources than Japan, and that his country could not win a protracted war. As Steve Twomey details in his 2016 book Countdown to Pearl Harbor: The Twelve Days to the Attack, Yamamoto believed that Japan’s only chance for success was to stage a surprise assault that would knock the U.S. fleet out of action for a year or more.
  • Japanese forces trained for about a year to prepare for the attack. They added wooden fins to their aerial torpedoes and made other modifications, so that they could work on short runs at the 45-foot average depth of Pearl Harbor.
  • The Japanese Foreign Ministry wanted to present the United States with a declaration of war prior to the attack, so that they wouldn’t violate international law. But they were blocked by the Japanese military, which didn’t want to jeopardize the operation.
  • The Japanese attack force—which included six aircraft carriers and 420 planes—sailed from Hitokappu Bay in the Kurile Islands, on a 3,500 mile voyage to a staging area 230 miles off the Hawaiian island of Oahu. According to Twomey, the Japanese sailed without radar or reconnaissance planes overhead, in an effort to avoid detection.

The U.S. Missed Signs of Japan’s Preparations

  • U.S. officials overlooked Japanese forces’ preparations for war, and missed warning signs of the impending attack, including an intercepted December 6 Japanese message asking about berthing positions at Pearl Harbor, and a radar sighting of a large group of airplanes headed toward Oahu on the morning of December 7.
  • The first wave of the attack included 180 Japanese aircraft, including torpedo planes, high-level bombers, dive bombers and fighters. They were followed by a second wave of similar size, but with more dive bombers and no torpedo planes.
  • Japanese forces started the attack shortly before 8 a.m. Hawaiian time, when the initial wave of fighters struck, according to U.S. Naval History and Heritage Command.
  • According to a 2016 article by retired U.S. Navy Commander Alan D. Zimm, Japanese Captain Mitsuo Fuchida, who led the aerial attack on Pearl Harbor, made a critical mistake by firing two flares, which signaled to his aviators that they had not caught the Americans by surprise. As a result, they used more cautious tactics and inflicted far less damage than they might have.
  • The Japanese attack lasted nearly two hours.

The U.S.S. Arizona Was Struck by Several Bombs

Despite Surprise, U.S. Forces Fought Back Hard

Japan’s Attack Failed to Disarm the U.S. Fleet

  • Despite inflicting heavy casualties, the Japanese attackers failed to achieve their objective of disabling the U.S. fleet. No U.S. aircraft carriers were at Pearl Harbor that day, and the Japanese were unable to destroy vital infrastructure such as repair shops and fuel tanks.
  • In Washington, President Franklin D. Roosevelt learned of the attack during lunch, when he received a phone call from Secretary of the Navy Frank Knox.
  • Yamamoto, the architect of the attack, didn’t survive to see Japan’s eventual defeat. He was killed in 1943, when American fighters shot down his plane over the Solomon Islands.

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