World Facts

When Was Pearl Harbor Attacked?

Pearl Harbor, Hawaii was attacked on December 7, 1941.


The attack on Pearl Harbor was a surprise bombardment of the United States naval base at Pearl Harbor, Hawaii Territory (Hawaii had not yet become a US state), by the Imperial Japanese Navy Air Service. The attack occurred at dawn on December 7, 1941, and was intended as a preventive measure to keep the United States from interfering in Japan's military activities in Southeast Asia. However, instead, the attack caused the US to enter the Second World War. The Japanese military named the attack "Operation Z" during its planning phase, and then "Hawaii Operation" thereafter. For more than seven hours, the Japanese navy conducted coordinated attacks on US bases in Pearl Harbor, the Philippines, Wake Island, Guam, as well as the British Empire in Hong Kong, Singapore, and Malaysia.

The Attack

The attack on Pearl Harbor began at 7:48 a.m. Hawaiian Time (HAST), and was executed by 353 aircraft, including dive bombers, torpedo bombers, and fighters launched from aircraft carriers. The eight American battleships in the harbor were damaged, and four were sunk. All sunken ships, except the USS Arizona, were raised, and six were later repaired and rejoined the war. The attack also damaged or sunk three destroyers, three cruisers, a minelayer, and a training ship. In total, 188 American aircraft were destroyed, 2,403 Americans were killed, and a further 1,178 were wounded. However, the attack failed to destroy vital installations including the shipyard, dry dock, power station, torpedo and fuel storage facilities, submarine piers, and the headquarters building. Only one Japanese sailor was captured. A day after the attack on Pearl Harbor, Japan declared war against the United States.


The attack shocked US citizens and propelled the United States to enter the Second World War in both the Pacific and European fronts. On December 8, 1941, a day after the attack, the United States and Japan declared war on each other. Three days later, Germany and Italy also declared war on the United States. In response, the US declared war against both countries. American citizens, who had largely supported non-interventionism until that point, did not object to the declarations of war following the assault on Pearl Harbor. The Tokyo Trials, which were conducted after the war in 1946, concluded that the attack on Pearl Harbor constituted a war crime because it occurred without a declaration of war or any formal warning, and at a time when peace negotiations were ongoing.

Why Was the Attack Successful?

The Japanese navy was able to successfully conduct an attack on Pearl Harbor because of communication breakdowns between various branches of the US government and the armed services. The island was poorly defended against air attacks, as American military commanders underestimated Japan's ability to conduct a raid of such a large scale. Additionally, it is unclear how much intelligence had been collected about a possible Japanese attack on American installations, and if so, whether such information was taken seriously. Shortly after the attack, two of the base's military commanders, Admiral Husband E. Kimmel and Lieutenant General Walter Short, were demoted.


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