On December 7, 1941, Japanese launched a surprise attack on the US naval base at Pearl Harbor, Hawaii. The assault shocked the United States and propelled the nation into the Second World War. Today, we look back and ask: why did Japan decide to do this attack, and why was it, as US President Franklin D. Roosevelt said, “a date which will live in infamy?”
Japanese attack on Pearl Harbor
The Japanese attack began minutes before 8:00 AM. The majority of the US Pacific Fleet was anchored at Pearl Harbor, with the exception of three aircraft carriers. Appearing from enemy carriers out of sight over the horizon, 353 Japanese aircraft bombarded the naval base with bombs and torpedoes. They came in two waves, the first equipped to deal with the heavier, more important American ships. Submarines also participated in the attack.
The assault caught the Americans completely off-guard. Men were roused from their beds by alarms and explosions, rushing to take up defensive positions. The attack lasted less than 90 minutes; the third wave was canceled, in part due to the determined resistance put up against the second wave.
Over 2,400 Americans died in the assault, while 1,178 were wounded. Battleships and other vessels were lost or damaged. On top of this, 188 aircraft were destroyed and 159 damaged. In comparison, the Japanese only lost five mini submarines and 29 aircraft. One enemy combatant was captured, while 129 were killed.
Background of Japanese-American relations
The United States and Japan had been preparing for the possibility of war since the 1920s. Following the outbreak of hostilities between Japan and China in 1937, those tensions escalated at a rapid pace, especially with the massacre of Chinese civilians, which turned American opinion heavily against the Japanese. This, among other reasons, led the US to begin providing supplies to the Chinese.
When Japan invaded French Indochina in 1940, the US cut off much of the critical trade between them, further raising the stakes. With Japan increasingly expansionary and America increasingly restrictive in its trade, a war began to look inevitable. So why was it so shocking when it arrived?
Why was the Japanese attack on Pearl Harbor such a shock?
Japan and the United States had been in negotiations throughout 1941, trying to improve relations and maintain peace. The collapse of the conciliatory Konoe government made peace less likely, but talks were still in progress. As World War II was becoming global, many in America wanted to avoid involvement, and as Japan had allied with Germany and Italy, any fight against the country would draw the US into the bloody mess engulfing Europe.
The Japanese deliberately waited until the last moment to declare war. It’s likely that the surprise attack would have shocked and outraged Americans regardless, but the infamy of the assault was made worse by an error of timing. A declaration of war was meant to be handed to the US government just before the attack began, but it took longer than initially expected to transmit and transcribe.
As a result, the two weren’t formally at war when the attack began.
Why strike Pearl Harbor?
The strategic advantage for Japan in taking out the US Pacific Fleet was clear. By not trading, the United States was cutting off Japanese access to important industrial resources – in particular, oil. The Japanese response was to seize land that would give them access to these resources or to control trade. This might not force outsiders to trade with Japan, but it could prevent them from supplying China.
Many of these territories were European colonies. With Europe busy with its part of World War II, the US was the only power likely to challenge Japan’s plans, making the fleet a menace. The Two-Ocean Navy Act of 1940 created time pressure, as it set America on course to increase its naval forces by 70 percent. If Japan was going to act, it needed to do so now, before its fleets were completely outnumbered.
Tactically, the attack on Pearl Harbor came from balancing costs and benefits. Being in the harbor, the ships would be easy to find, unable to maneuver and unprepared to defend themselves. They would be sitting ducks. On the other hand, the shallow water would make them easier to salvage and mean more survivors among their crews.
Aside from the physical impact, the Japanese believed that a single shock attack would fracture American morale, making it harder for the US to commit to and maintain a war. In essence, they hoped to shock the country into a swift surrender.
Surprising the American forces on Pearl Harbor
Ironically, the decisive influence in Japanese strategy was an American: Alfred Thayer Mahan. His writings about warfare were a major influence on the Imperial Japanese Navy (IJN), leading the service to seek a single decisive action that would allow for the destruction of as many ships as possible, to gain a swift victory.
Surprise was vital to this. The Japanese needed the Americans to be unprepared, so they could catch as much of the US Pacific Fleet at anchor as possible. The surprise would minimize preparedness at Pearl Harbor, reducing both resistance and Japanese casualties. The shock value of the assault would also be accentuated by surprise.
More from us: Operation K: The Lesser-Known Japanese Attack Against the US Pacific Fleet
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Ultimately, this shock value, exaggerated by the delayed declaration of war, led to outrage and hostility from the United States, rather than surrender. As the following years showed, the war was won by a slow grind and a mass industrial process that was backed by the will to win. The date of infamy only added to that will.