Copyright

Atomic Bombings of Hiroshima and Nagasaki

Amanda Knapp, Alexandra Lutz
  • Author
    Amanda Knapp

    Amanda Knapp has taught and tutored English at the college level for over ten years. She taught English to Chinese children for over two years. She has a Master of Arts degree in English from Northern Illinois University and a Bachelor of Arts degree in advertising from Marquette University where she also minored in marketing and psychology. She has numerous articles and essays published.

  • Instructor
    Alexandra Lutz

    Alexandra has taught students at every age level from pre-school through adult. She has a BSEd in English Education.

Review the atomic bombings of Hiroshima and Nagasaki. Learn the background and development of the atomic weapon and study the aftermath of the bomb blast. Updated: 04/09/2022

Atomic Bombings of Hiroshima and Nagasaki

The only two times nuclear bombs were detonated in acts of war were by the United States in Japan, shortly before the end of World War II. These bombs landed on the cities of Hiroshima and Nagasaki and precipitated the end of the war. Proponents of the bombs claim they saved countless American lives by hastening Japanese surrender while opponents say the Japanese may have surrendered without the destruction that the bombs caused. This lesson will explore the two bombings in detail.

War in the Pacific Drags On

Following the attack on Pearl Harbor, Hawaii, on December 7, 1941, it took six months for the United States to stem the tide of Japanese aggression. And for most of the next two years, Allied troops in the Pacific pushed Japan back in a series of difficult conflicts. The worst fighting started in 1944 as Japan became increasingly concerned about protecting its homeland.

In March 1945, American troops conquered Iwo Jima. Just 350 miles from Japan, the island's defenders fought nearly to the last man. A third of all U.S. Marine casualties in the entire war were at Iwo Jima. Meanwhile, American bombers were raining destruction on Japan, targeting airfields and ports and cities. After just two days, miles of city streets were leveled, a million people were left homeless and 100,000 people were dead - and that was just in Tokyo. But Japan refused to surrender. When American troops invaded Okinawa, they met even stiffer resistance. The Japanese defenders and civilians fought desperately for nearly three months, and sent in a rain of kamikaze attacks. Before it was over, they had inflicted nearly 50,000 U.S. casualties while losing as many as 200,000 of their own, but they still refused to surrender.

Meanwhile in the U.S., its wartime leader Franklin Roosevelt died, Harry Truman became president, and Germany was defeated. In July 1945, Truman met with other Allied leaders at Potsdam to discuss next steps, including an invasion of Japan itself.

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Who Dropped the Atomic Bomb?

The dropping of the bombs by the United States took part in the context of World War II. On December 7, 1941, Japan invaded Pearl Harbor. America joined the war, and what followed was years of fighting Japan in the Pacific. Rather than lessening, the fighting became more deadly as time wore on and the Japanese became more desperate to avoid surrender.

In March of 1945, the battle of Iwo Jima occurred. Almost one-third of the United States Marine casualties during the entire war occurred in Iwo Jima, while the islanders of Iwo Jima fought nearly to the last man.

At the same time, America was targeting Japan, bombing both airfields and cities. In Tokyo alone, 100,000 people were killed and over a million were left homeless in the attacks. The fighting was even more brutal in Okinawa. During the three months of fighting there, Americans sustained nearly 50,000 casualties and inflicted nearly 200,000 more. Still, Japan refused to surrender.


The billowing cloud of smoke after Hiroshima

Black and white photo of smoke billowing from the Earth after the Hiroshima bomb date


Development of the Atomic Bomb

The development of the atomic bomb began in America before the United States entered World War II. Scientists in America, including ex–German Jewish scientist Albert Einstein, discovered that Adolf Hitler’s Germany was attempting to split the uranium atom.

The United States, under President Franklin D. Roosevelt, responded with the Manhattan Project, a project so secret that even Vice Present Harry S Truman did not know about it. What started with $6,000 and three university labs grew into a $2 billion project with thirty locations in the United States, Canada, and Great Britain, employing over 130,000 people. The project's goal was to develop a nuclear weapon

The project, under the direction of J. Robert Oppenheimer, attempted explosion and implosion weapons with both uranium and plutonium. The world’s first nuclear bomb was detonated at the Trinity Site in a southern desert in New Mexico on July 16, 1945. The resultant mushroom cloud stretched 40,000 feet, the flash was visible for 200 miles, and windows were blown out 100 miles away.

The Potsdam Declaration

After Germany’s surrender in Europe, the war continued in the Pacific against the Japanese. Three leaders, Harry S Truman (United States), Winston Churchill (Great Britain), and Chiang Kai–shek (China), met in Potsdam, Germany. On July 26, 1945, they issued a statement to Japan outlining terms of surrender and threatening ''prompt and utter destruction'' should Japan fail to surrender. Japanese Emperor Hirohito refused to surrender despite Japan’s increasing casualties. The Potsdam Declaration went unheeded.

Attack on Hiroshima and Nagasaki

On August 6, 1945, American bomber ''Enola Gray'' dropped the first atomic bomb ever to be used in war on Hiroshima. The bomb dropped that date was nicknamed ''Little Boy.'' Hiroshima was known as a center of war industries and military operations.

On August 9, the American bomber ''Bockscar'' dropped the second atomic bomb, nicknamed ''Fat Man'' on Nagasaki. This location was chosen because thick clouds made dropping the bomb on the chosen city of Kokura less than ideal.

Hiroshima Nagasaki
Nickname Little Boy Fat Man
Bomber Name Enola Gray Bockscar
Type Uranium Plutonium
Weight 9,000lb 10,000lb
Land Destroyed 5 square miles 2.6 square miles
Immediate Deaths 80,000 40,000

On the same day, as the bomb at Nagasaki was dropped, Chinese troops invaded Japanese–held Manchuria in China. This cut off crucial coal and strategic resources to Japan.

On August 15, 1945, the Japanese surrendered. August 14th (different from the aforementioned August 15 because of time zone differences) is known as VJ Day, or Victory in Japan Day, in the United States.

How Many People Died in Hiroshima and Nagasaki?

Definitive casualties able to be attributed to the bombs cannot be known because residents of the two cities remained at high risk of cancer for decades after the blasts. The immediate death toll at Hiroshima was about 80,000 while the immediate death toll at Nagasaki was about 40,000. Most of the dead were Japanese civilians. Long-term, it is believed that a total of 70,000 to 135,000 people died as a result of the bomb in Hiroshima, and between 60,000 and 80,000 people died as a result of the bomb dropped on Nagasaki.

Manhattan Project

While he deliberated the planned invasion, President Truman learned about the Manhattan Project, a secret program to develop a powerful new weapon: the atomic bomb.

It began, in some ways, before America even entered the war. Upon Adolf Hitler's rise to power, Albert Einstein, the famous German Jewish physicist, had fled to the United States. And then in 1939, Einstein and other leading scientists learned that Germany was working to split a uranium atom. They quickly contacted President Roosevelt to urge him to begin a nuclear program, and thus began America's Advisory Committee on Uranium. From very humble beginnings with just $6,000 and three university labs, the program grew to include 30 sites in the U.S., Canada and Britain, with more than $2 billion in funding. In 1941, it was code-named the Manhattan Project, though its main facility was high in the mountains of Los Alamos, New Mexico. In addition to developing an atomic weapon, the program also gathered intelligence on Germany's project from behind enemy lines. Ultimately, the Manhattan Project employed over 130,000 people. Under the direction of J. Robert Oppenheimer, the massive research project was kept secret from even the vice-president. Ironically, the Soviet Union had learned about it from a well-placed spy.

After experimenting with both uranium and plutonium, as well as trying both explosion- and implosion-type weapons, the world's first nuclear bomb was detonated at the Trinity Site, in the desert of southern New Mexico. Even the scientists who had developed the bomb were shocked by its power. A mushroom cloud stretched 40,000 feet into the sky. The blinding flash was visible for 200 miles, and a shock wave blew out windows 100 miles away. The desert for half a mile was turned into glass. Civilian witnesses to the destruction were assured that an ammunition dump had exploded.

Three years of intense work had paid off. It was July 16, 1945, the day before the Potsdam Conference convened.

Dropping Atomic Bombs on Hiroshima and Nagasaki

By most accounts from the period, the decision to use the new weapon against Japan was fairly simple. The slow progress of the island invasions and Japan's refusal to surrender were becoming expensive, both in terms of dollars and human casualties. The war had been a bloody grind that laid waste to large swaths of Asia and Europe. If the goal was to end the war as soon as possible, why wouldn't America and its allies use every weapon at its disposal to do just that? Keep in mind that the conventional bombings in Germany and Japan up to that point were already deadly and destructive to civilian targets. Truman also justified the attack as retribution for Pearl Harbor, saying, 'When you have to deal with a beast, you have to treat him as a beast.' Finally, using this impressive new weapon was a way to project an image of power to Josef Stalin and the Soviet Union, with whom tensions were increasing quickly. There was potential for the new weapon to improve the American position in the negotiations to follow the conclusion to the fighting.

Truman approved the bombing of selected Japanese targets. Before they were dropped, the Potsdam Declaration of July 26 sent an ultimatum to Japan: surrender unconditionally or face prompt and utter destruction. The Emperor never responded.

On August 6, 1945, the American bomber Enola Gay dropped a bomb nicknamed 'Little Boy' on Hiroshima, a center of war industries and military operations. Temperatures reached tens of millions of degrees, and the flash was ten times brighter than the sun. Within minutes, two-thirds of the city's buildings disappeared and up to 80,000 people died. But Japan did not surrender. Three days later, August 9, the United States dropped a second nuclear weapon, called 'Fat Man,' on Nagasaki. A third of the city and roughly 40,000 people were destroyed. That same day the Soviet Union, with whom Japan had tried to make peace, invaded Japanese-occupied Manchuria in northeastern China, an area which was vital for Japan's access to coal and other strategic resources. Finally, with almost no ability to wage war and unwilling to endure more destruction and loss of life, Emperor Hirohito decided to surrender, without knowing Truman had called off any further atomic strikes. Although a few Japanese generals attempted a military coup, preferring to fight to the death rather than surrender, they were defeated.

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Video Transcript

War in the Pacific Drags On

Following the attack on Pearl Harbor, Hawaii, on December 7, 1941, it took six months for the United States to stem the tide of Japanese aggression. And for most of the next two years, Allied troops in the Pacific pushed Japan back in a series of difficult conflicts. The worst fighting started in 1944 as Japan became increasingly concerned about protecting its homeland.

In March 1945, American troops conquered Iwo Jima. Just 350 miles from Japan, the island's defenders fought nearly to the last man. A third of all U.S. Marine casualties in the entire war were at Iwo Jima. Meanwhile, American bombers were raining destruction on Japan, targeting airfields and ports and cities. After just two days, miles of city streets were leveled, a million people were left homeless and 100,000 people were dead - and that was just in Tokyo. But Japan refused to surrender. When American troops invaded Okinawa, they met even stiffer resistance. The Japanese defenders and civilians fought desperately for nearly three months, and sent in a rain of kamikaze attacks. Before it was over, they had inflicted nearly 50,000 U.S. casualties while losing as many as 200,000 of their own, but they still refused to surrender.

Meanwhile in the U.S., its wartime leader Franklin Roosevelt died, Harry Truman became president, and Germany was defeated. In July 1945, Truman met with other Allied leaders at Potsdam to discuss next steps, including an invasion of Japan itself.

Manhattan Project

While he deliberated the planned invasion, President Truman learned about the Manhattan Project, a secret program to develop a powerful new weapon: the atomic bomb.

It began, in some ways, before America even entered the war. Upon Adolf Hitler's rise to power, Albert Einstein, the famous German Jewish physicist, had fled to the United States. And then in 1939, Einstein and other leading scientists learned that Germany was working to split a uranium atom. They quickly contacted President Roosevelt to urge him to begin a nuclear program, and thus began America's Advisory Committee on Uranium. From very humble beginnings with just $6,000 and three university labs, the program grew to include 30 sites in the U.S., Canada and Britain, with more than $2 billion in funding. In 1941, it was code-named the Manhattan Project, though its main facility was high in the mountains of Los Alamos, New Mexico. In addition to developing an atomic weapon, the program also gathered intelligence on Germany's project from behind enemy lines. Ultimately, the Manhattan Project employed over 130,000 people. Under the direction of J. Robert Oppenheimer, the massive research project was kept secret from even the vice-president. Ironically, the Soviet Union had learned about it from a well-placed spy.

After experimenting with both uranium and plutonium, as well as trying both explosion- and implosion-type weapons, the world's first nuclear bomb was detonated at the Trinity Site, in the desert of southern New Mexico. Even the scientists who had developed the bomb were shocked by its power. A mushroom cloud stretched 40,000 feet into the sky. The blinding flash was visible for 200 miles, and a shock wave blew out windows 100 miles away. The desert for half a mile was turned into glass. Civilian witnesses to the destruction were assured that an ammunition dump had exploded.

Three years of intense work had paid off. It was July 16, 1945, the day before the Potsdam Conference convened.

Dropping Atomic Bombs on Hiroshima and Nagasaki

By most accounts from the period, the decision to use the new weapon against Japan was fairly simple. The slow progress of the island invasions and Japan's refusal to surrender were becoming expensive, both in terms of dollars and human casualties. The war had been a bloody grind that laid waste to large swaths of Asia and Europe. If the goal was to end the war as soon as possible, why wouldn't America and its allies use every weapon at its disposal to do just that? Keep in mind that the conventional bombings in Germany and Japan up to that point were already deadly and destructive to civilian targets. Truman also justified the attack as retribution for Pearl Harbor, saying, 'When you have to deal with a beast, you have to treat him as a beast.' Finally, using this impressive new weapon was a way to project an image of power to Josef Stalin and the Soviet Union, with whom tensions were increasing quickly. There was potential for the new weapon to improve the American position in the negotiations to follow the conclusion to the fighting.

Truman approved the bombing of selected Japanese targets. Before they were dropped, the Potsdam Declaration of July 26 sent an ultimatum to Japan: surrender unconditionally or face prompt and utter destruction. The Emperor never responded.

On August 6, 1945, the American bomber Enola Gay dropped a bomb nicknamed 'Little Boy' on Hiroshima, a center of war industries and military operations. Temperatures reached tens of millions of degrees, and the flash was ten times brighter than the sun. Within minutes, two-thirds of the city's buildings disappeared and up to 80,000 people died. But Japan did not surrender. Three days later, August 9, the United States dropped a second nuclear weapon, called 'Fat Man,' on Nagasaki. A third of the city and roughly 40,000 people were destroyed. That same day the Soviet Union, with whom Japan had tried to make peace, invaded Japanese-occupied Manchuria in northeastern China, an area which was vital for Japan's access to coal and other strategic resources. Finally, with almost no ability to wage war and unwilling to endure more destruction and loss of life, Emperor Hirohito decided to surrender, without knowing Truman had called off any further atomic strikes. Although a few Japanese generals attempted a military coup, preferring to fight to the death rather than surrender, they were defeated.

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Frequently Asked Questions

How did the atomic bomb affect Japan?

The atomic bombs killed tens of thousands of Japanese people instantly. Many more died in the months to come from burns and illnesses related to the bombs. Citizens of Hiroshima and Nagasaki remained at increased risk for cancer for the remainder of their lives.

Why did the US drop the atomic bomb?

The United States dropped the atomic bomb for multiple reasons. President Truman wanted to save American lives that would be lost should an invasion of Japan become necessary. He was also looking to make a statement of strength to the Soviet Union.

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