On 7 December 1941, the Imperial Japanese Navy attacked the US naval base of Pearl Harbor in Oahu, Hawaii. The bombardment was intended as a pre-emptive strike, despite the United States being a neutral country at the time. The intensity and destructiveness of the attack shocked the world, and it was later judged to be a war crime.
The attack on Pearl Harbor transformed the wars being fought in Europe and the Far East into a truly global conflict, as Britain and America subsequently declared war on Japan, while Germany and Italy declared war on America and America responded in kind. Within 48 hours, World War Two had escalated dramatically.
But how did the events of 7 December actually play out? We’ve pulled together a guide to the events that happened before, during and after the infamous attack on Pearl Harbor.
5 November: Emperor Hirohito approves plans for an attack on Pearl Harbor
Relations between Japan and America had been growing increasingly strained throughout the late 1930s, and by 1940, things were tense. President Franklin D. Roosevelt moved the US Pacific Fleet to Hawaii from San Diego and ordered an increased US military presence in the Philippines, provoking fears in Japan of an attack.
In early 1941, as the US ceased oil exports to Japan, preliminary planning for an attack on Pearl Harbor began, and over the subsequent months, Japan focused on gaining intelligence, training up relevant personnel, studying plans and adapting equipment. Pearl Harbor was an important US naval base in the Pacific, making it one of the biggest threats to Japan as a result.
On 5 November 1941, Emperor Hirohito finally approved the plans, and subsequently went on to authorise the attack on 1 December, just under a week before it finally took place.
20 November: Japan’s final proposal for peace delivered to Allied forces
Despite difficult relations, Japan and the United States were working to achieve some form of peace: negotiations were somewhat fraught, however, and the two sides struggled to agree on particular aspects of trade and military action.
Japan delivered its final peace proposal to Allied forces on 20 November, which the Allies subsequently countered, deeming the terms proposed by Japan insufficient.
25 November: a small fleet of submarines is dispatched from Japan
Before receiving the Allied response to the final peace proposal, the Imperial Japanese Navy dispatched 5 I-boat submarines across the Pacific, heading for Pearl Harbor. Whilst nothing was certain at this point, Japan certainly saw war as the only option if these terms were rejected.
6:10 am, 7 December: Japanese aircraft take off, 200 miles north of Oahu
The first wave was comprised of 171 planes (6 failed to launch), split into 3 groups. Launching north of Oahu, they were detected by US radar systems as they arrived at the northern tip of Oahu at 7:02 am, and this news was passed on to other US officials.
In a stroke of bad luck, it was presumed that this was the scheduled arrival of B-17 bombers from California: because of the close formation of the planes, they appeared in an unusual way on the radar. At 7:20 am, the warnings received were disregarded.
7:55 am, 7 December: the first wave of co-ordinated attacks on Pearl Harbor begins
Taking advantage of the confusion and lack of transmission of warnings, 49 800kg bombs were dropped in the first wave: around 8 of these hit their intended targets, with the remaining bombs hitting surrounding areas.
US forces were completely unprepared for such an attack: guns were unmanned, ammunition lockers locked and aircraft parked wingtip to wingtip, making them tricky to launch. Military personnel responded surprisingly quickly given the circumstances, but could do little to stop the barrage of attacks.
8:52 am, 7 December: the White House Press Secretary announces the attack
At 2:22 pm EST (8:52 am in Hawaii), the White House Press Secretary first announced “the Japanese have attacked Pearl Harbor from the air and all naval and military activities on the island of Oahu, principal American base in the Hawaiian islands”, bringing news of the attack to the attention of not only America, but also the world.
Most American citizens learnt about the attack from a CBS radio broadcast a few minutes later.
8:54 am, 7 December: the second wave of attacks begins
The second wave consisted of 167 planes (an extra 4 failed to launch because of technical difficulties), armed with huge quantities of bombs and explosives. Divided into 3 groups, 1 attacked Kāneʻohe whilst the other two aimed for Pearl Harbor itself. They arrived at their attack points almost simultaneously, coming from different directions.
The second wave inflicted further damage, including the destruction of the USS Shaw, one of the US navy’s destroyers, which exploded in dry dock following several hits.
10 am, 7 December: the attack is over
By 10 am, the attack was over: Japanese aircraft headed back to the carriers, and then ultimately returned to Japan. The attack on Pearl Harbor had devastated parts of the US Navy, damaging all of the battleships present and sinking half of them.
Over 188 US aircraft were destroyed, and 2,403 Americans were killed in the attack. Japanese forces, on the other hand, suffered only 64 personnel killed and light losses to their aircraft and submarines.
8 December: War
Pearl Harbor was not the only attack carried out by the Japanese that day. British and American territories across the Pacific region were targeted, including Guam, British Malaya, Singapore and Hong Kong. Japan declared war on Britain and America several hours after these attacks were launched.
Britain declared war with Japan 9 hours before America did, mainly due to the fact that the Cabinet did not require permission from Parliament to declare war, whereas America required the consent of the national legislature.
By the evening of 8 December 1941, Britain and America were at war with Japan, meaning the United States had entered World War Two, scaling up the conflict.
Just 3 days later, Germany and Italy declared war on America: by Christmas 1941, what would become all of the major theatres of war were in play.