The devastating Japanese attack on Pearl Harbor on December 7, 1941, marked a dark chapter in US history, causing the loss of thousands of military personnel and civilians. This surprise attack drew the nation into World War II, strengthening the Allies’ efforts in both the European and Pacific Theaters.
Despite the event’s fame, many historians and non-historians continue to struggle to understand the complicated motivations behind Japan’s decision to strike Pearl Harbor.
Japan changed direction during the Great Depression
With the Great Depression hitting the world in the 1930s, along with the rise of authoritarian regimes in Europe and growing Chinese nationalism, Japan was forced to make a shift in its policies. The result: even more aggressive expansion.
This led the country’s military to invade Manchuria in September 1931, preluded by the staged Mukden Incident. Within half a year, Japan had secured control of the region and set up a puppet state, known as Manchukuo. While Western powers decried Japan’s invasion, little else was done, as the majority of countries didn’t want to go to war.
For the United States, in particular, the Stimson Doctrine guided decision-making during this time. While it allowed the country to speak out against the invasion, it was ineffective in that it didn’t prompt the US to impose material sanctions upon Japan. At the time, many didn’t see much wrong with this, given the isolationist stance held by the majority of Americans, and government officials were worried about intervening, given the ongoing strife between Chinese nationalists and Communists.
Japan wanted to become a global superpower
To understand why Japan initiated the attack on Pearl Harbor, one must go back to the late 19th century and the decline of the Tokugawa shogunate. Concurrently, under Emperor Meiji, efforts were underway to elevate Japan into a leading global power.
A crucial component of this involved the expansion and modernization of Japan’s economy, coupled with the need for increased access to natural resources. Given the country’s relatively small size, it faced limitations in resources that hindered its aspirations for economic and population growth.
Consequently, plans were devised to invade nations in the Indo-Pacific and neighboring regions, marking the commencement of what historians have termed an aggressive period of expansionism.
Growing Japan’s economic prospects during the early 20th century
One of the methods Japan used to expand its territory at the turn of the century was through conflict. The nation’s military engaged in wars with both China (1894-95) and Russia (1904-05) to gain control of food supplies and other resources along the Korean Peninsula and northeastern China, commonly known as Manchuria.
These victories achieved Japan’s objectives, with the country being acknowledged as a “great” power in the Treaty of Versailles following World War I, and its influence only continued to grow. During the interwar period, Japan aimed to establish peaceful relationships with other countries, negotiating agreements for various raw materials. Notably, it secured crucial supplies from the United States and Manchuria, including petroleum, steel, grains, and coal.
Things continued to get worse in Manchuria
In 1933, with no sign that Japan would be leaving Manchuria anytime soon, the League of Nations condemned the invasion, to which Japan responded by withdrawing from the international organization. Following this, Japan became more aggressive in expanding its territory and power, withdrawing from naval agreements that limited the size of its navy, and doubling the size of its armed forces within the span of five years.
By October 1937, US President Franklin D. Roosevelt had become concerned enough about what was happening in Asia, as well as the ongoing Spanish Civil War, that he made a public statement, in which he said the “very foundations of civilization” were being “seriously threatened.” He was also worried that Japan would continue its expansionist movements into both the Philippines and Hong Kong, a move that would directly threaten the United States.
Tensions only began to grow in 1937-38, following the Nanjing Massacre, the bombing of the USS Panay (PR-5) and the Allison Incident. This led the US to increase trade to China, followed by economic sanctions upon Japan, which included the banning of the export of iron ore, aircraft materials and steel.
While all this was to make Japan wary of further action, it only angered the country’s government. In September 1940, it signed the Tripartite Pact with Germany and Italy, and a Neutrality Pact was signed with the Soviet Union the following year. While the latter was an ally of the US, the move meant Japan would be focusing its attention on southeast China, where American interests lay.
On top of all this, Japan signed a third pact, this time with Vichy France, which allowed its military to move into Indochina and continue the nation’s advance into southern Asia.
The United States froze all of Japan’s assets
In 1941, when Japan invaded and occupied Indochina, the United States, in collaboration with the Dutch and British, reacted by freezing all Japanese assets. This was a significant economic setback, with the sanctions causing a 94 percent drop in oil. This is said to have led Japan to begin planning an attack on the colonial territories of the trio.
However, Japan faced a significant challenge: any attack on these Pacific territories would provoke a military response from the US, a conflict they knew they could not win. This led to the development of the “Southern Operation,” which involved attacks on the US at Pearl Harbor and the Philippines and on the British at Singapore.
Japan plans its attack on Pearl Harbor
While a number of officials were involved in the planning of the Japanese attack on Pearl Harbor, the person who did the most work was Adm. Isoroku Yamamoto, who spent months devising a way to decimate the US Pacific Fleet and strike a blow to the country’s morale.
The decision was made to obliterate America’s naval capacity in the Pacific in one fell swoop. By doing so, the belief was that the Japanese could take the Philippines and British Malaya by the time the US had rebuilt, and build enough of a defensive barrier to prevent them from launching an effective counterattack, even months down the road.
Throughout the planning stage, Japan engaged in negotiation talks with the US, to no avail. When the latter issued a 10-point statement about its position, the Imperial Japanese Navy (IJN) decided it was time to strike.
Pearl Harbor wasn’t the only place Japan attacked
On December 7, 1941, Japan did as it had planned and launched a large attack on Pearl Harbor. The naval base wasn’t believed to have been a viable target, so the United States hadn’t provided it with near enough defensive measures, giving the Japanese a bit of an edge, along with the surprise nature of the strike.
What many don’t realize, however, is that Pearl Harbor wasn’t the only place targeted by the Japanese that day. While they may have been recorded as having occurred on December 8, given the time zone difference, strikes were launched on Guam, Malaya, Hong Kong, Singapore, Wake Island and the Philippines – all British and American territories.
In the Philippines, the Japanese took out almost an entire fleet of Curtiss P-40 Warhawks and Boeing B-17 Flying Fortresses at Clark Field, prompting an immediate response from the US. Heavy combat ensued, with the Japanese ultimately securing a victory in 1942. By then, the military had also secured control of Hong Kong, the Dutch East Indies, Guam, British Malaya and Singapore.
The majority of these territories remained under Japanese control until the final year of the Second World War.
Japan’s attack on Pearl Harbor wasn’t all that damaging
While, at first, the Japanese attack on Pearl Harbor looked successful, the fact of the matter was that a good portion of the US Pacific Fleet wasn’t stationed at Ford Island. While eight battleships and hundreds of aircraft were bombarded by bombs, the bulk of America’s naval power was unscathed, including tankers, repair facilities and ammunition sites.
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Most importantly, the US Navy’s fleet of aircraft carriers wasn’t moored at Pearl Harbor. This came back to bite the Japanese in June 1942 when three carriers – the USS Yorktown (CV-5), Enterprise (CV-6) and Hornet (CV-8) – helped secure a crucial win at the Battle of Midway, which many view as the pivotal turning point of the war in the Pacific Theater.