What Happened after Pearl Harbor? (Attack + US Response)

Happened after Pearl Harbor attack

The Japanese surprise attack at Pearl Harbor on December 7, 1941 was a stunning blow to the United States. As the site of the US Pacific fleet, the garrison was completely caught off guard and unprepared for the attack. Just what happened after the attack on Pearl Harbor completely changed the course of the war.

Japan’s attack happened in a flash and was over in an instant. When the dust settled, thousands of servicemen lay dead and dozens of ships damaged or sunk.

The lead up to the attack on Pearl Harbor was decades in the making. Japan began its ascent to world power status with the Meiji Restoration in the late 20th century. After a shocking victory over the Russians in the Russo-Japanese War of 1905, Western nations were forced to reckon with the emerging Japanese power.

Tensions between the United States and Japan were inevitable. The resource-poor Japanese sought to emulate the Western powers and expand their sphere of influence with colonies in Eastern Asia.

Japan and the Western nations increasingly squabbled over their share of East Asian colonies, markets, and natural resources. This came to a head in 1931 when the Japanese attacked the Manchuria region of China.

The US responded with the Stimson Doctrine; a policy in support of Chinese sovereignty and denouncing Japanese aggression. However, the doctrine was ineffective due to the failure to enact any material consequences on Japan.

As Japan further acted upon its imperial ambitions, the US increasingly enacted more forceful economic sanctions. Japan relied on the US for about 70% of its petroleum needs, and the US total embargo on petroleum and gasoline to Japan in August 1941 proved impactful.1

The escalating moves would soon erupt into war between the two nations, beginning with the surprise attack on Pearl Harbor.

Japan’s Plan to Attack Pearl Harbor

To Japan, war with the United States was inevitable. It was also a war Japan knew it could not win in the long run. The size differences and industrial capacity of the two countries were incomparable with the US holding a major advantage.

The mastermind behind the attack on Pearl Harbor was Japanese Admiral Isoroku Yamamoto. Yamamoto was Harvard-educated, fluent in English, and had traveled extensively around the United States to learn American customs and norms.

Yamamoto had great respect for America and knew the latent power it wielded. To his superiors, he consistently warned against war with the United States, knowing on level ground they could not win. He would remark:

“Anyone who has seen the auto factories in Detroit and the oil fields in Texas knows that Japan lacks the national power for a naval race with America.”

Nevertheless, Yamamoto followed his orders and planned the eventual attack on the United States. He knew that in order to have any shot at victory over the US, Japan must cripple the US Navy, place the US on the defensive, and utilize the time it took for the US to recover to entrench themselves on the resource-rich East Asian territories held by the Western powers.2

Aerial view of Pearl Harbor just before attack via Wikimedia

Yamamoto chose to attack Pearl Harbor – the location housing the US Pacific Fleet. Better yet, a surprise attack could catch the US off-guard and potentially prove to be a “knock-out” blow and eliminate the US naval threat.

While later admitting he conceived the plan “in desperation,” Yamamoto had high hopes that success could lead to lower American morale and eventual peace terms on a more level playing field. 

When Was Pearl Harbor Attacked?

Yamamoto’s master plan to attack Pearl Harbor was to take place at dawn on December 7, 1941. The Japanese strike force consisted of 353 aircraft flying off their 4 heavy aircraft carriers. Included was a mix of torpedo, level, and dive bombers as well as fighters, each to serve their own purpose.

The Japanese intended for their declaration of war on the United States to reach them 30 minutes before the attack so as not to break articles from the Hague Convention. Due to delays, the US did not receive the declaration until after the attack was in progress.

There is scholarly debate as to whether this was the Japanese intent, so as to not ruin their element of surprise. In some interpretations, the letter did not even consist of a declaration of war, just an end to negotiations.

Explosion of the USS Shaw via LOC

Nevertheless, the attack on Pearl Harbor proceeded with the first Japanese planes arriving at 7:55am. At the same time, Japan launched invasions of Malaya which would eventually lead to the critical Battle of Singapore.

A radar operator on the Hawaiian island of Oahu actually spotted the incoming Japanese planes, though a superior mistook them for American bombers. This mistake would prove costly. The entire attack at Pearl Harbor only lasted one hour and fifteen minutes.

In that time the Japanese inflicted a critical blow to the US Pacific Fleet, catching the naval base completely off guard over two separate waves of attack. The results would be shocking.

How Many People Died at Pearl Harbor?

In the attack the Japanese killed 2,335 US servicemen as well as 68 civilians, bringing the total dead at Pearl Harbor to 2,403. The US Navy bore the brunt of the carnage with 2,008 dead. The Army and Marines had 218 and 109 men killed, respectively.

In addition the United States counted another 1,178 wounded, bringing the total casualties to 3,581. The primary objective of the Japanese was to destroy as many US carriers and battleships as possible, hence the lopsided casualties by service.

The vast majority of the casualties came from the sinking of one ship: the USS Arizona. At the beginning of the attack four armor-piercing bombs hit the USS Arizona, the last of which detonated in a powder magazine, exploding the ship. It sank within 15 minutes of the attack, killing 1,177 of its crew members.

How many died in Pearl Harbor casualties chart

The USS Oklahoma was also a large loss. After taking direct hits by five torpedo bombs the ship capsized, killing 429 sailors.

A vast majority of those killed at Pearl Harbor were junior enlisted personnel. Officers lived in houses on the mainland, so primarily enlisted servicemen were present on the ships at those early hours.

In all, the Japanese sunk or severely damaged all eight battleships with numerous other naval ships such as cruisers, destroyers, and auxiliaries damaged or sunk as well. In addition, almost half the aircraft on the island (188) were destroyed, with another third critically damaged. Most never even made it off the ground.3

In the attack on Pearl Harbor, the Japanese lost only 29 aircraft and 129 men killed in action. After the second wave, the attackers considered their mission a success and returned back to Japan due to low fuel reserves.

What Happened after the Attack on Pearl Harbor?

Immediately after the attack on Pearl Harbor the United States declared war on Japan. President Franklin Delano Roosevelt called the attack a “date which will live in infamy,” and the nation transformed overnight from isolationist to over 97% of Americans supporting the war.

Japan soon dominated the Pacific as it followed Pearl Harbor with attacks on strategic southeast Asian sites like Singapore and Malaya as well as various Pacific islands like the Philippians and Guam.

The Japanese public worshiped Admiral Yamamoto for formulating the plan against the Americans. In reality, while Pearl Harbor was a significant tactical victory it would ultimately prove to be an enormous strategic mistake.

In a stroke of luck for the United States, their 3 Pacific aircraft carriers were all out at sea and not present during the attack. Carriers would ultimately be the decisive ships of the Pacific theatre and with the US carrier fleet intact they could respond more quickly.

Just six months later, the Americans utilized two of these three carriers in the critical Battle of Midway.

Date Live in Infamy Pearl Harbor
A draft of President Roosevelt’s “a date which will live in infamy” speech via archives.gov

In addition in their attempt to cripple the American fleet, the Japanese failed to destroy critical infrastructure at Pearl Harbor. With this infrastructure in place, the US was able to quickly repair nearly all the damaged ships and return them to service quicker than Japan thought possible.

Amazingly only two ships (Arizona and Oklahoma) were permanently destroyed and taken out of service.

The United States soon ramped up its wartime economy and proved Yamamoto correct that Japan stood no chance against the United States once its industry reached full capacity.

The attack on Pearl Harbor would eventually lead to the atomic bombings of Hiroshima and Nagasaki. The attack meant to secure Japan’s future ultimately led to the end of the rising sun.


To learn more about US history, check out this timeline of the history of the United States.


1) Hosoya, Chihiro. “Miscalculations in Deterrent Policy: Japanese-U. S. Relations, 1938-1941.” Journal of Peace Research, vol. 5, no. 2, 1968, pp. 97–115. JSTOR, http://www.jstor.org/stable/423231.

2) Caravaggio, Angelo N. “‘WINNING’ THE PACIFIC WAR: The Masterful Strategy of Commander Minoru Genda.” Naval War College Review, vol. 67, no. 1, 2014, pp. 85–118. JSTOR, http://www.jstor.org/stable/26397439.

3) Gompert, David C., et al. “Japan’s Attack on Pearl Harbor, 1941.” Blinders, Blunders, and Wars: What America and China Can Learn, RAND Corporation, 2014, pp. 93–106. JSTOR, http://www.jstor.org/stable/10.7249/j.ctt1287m9t.15.

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