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Kids learn about the history of the Atomic Bomb during World War II. Dropped on Hiroshima and Nagasaki of Japan to end WW2.

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While Germany had surrendered, the continued. One of the most significant events of World War Two happened in 1945. This was the dropping of on the Japanese cities of Hiroshima and Nagasaki by American forces.

The decision to drop the atom bomb was taken by President Harry S. Truman, who had replaced Franklin Roosevelt following his death in April 1945. On 6 August 1945, Truman ordered an atom bomb to be dropped on the city of Hiroshima. It was dropped by a bomber plane named the Enola Gay. It is thought that at least 140,000 people were killed, of a total population of around 350,000.

When the atom bomb was dropped:

The temperature at the centre of the explosion reached 3000ºC - 4000ºC - three times hotter than volcanic lava.

Everything within a mile of the centre of the blast was flattened.

Fires spread and around 67 per cent of Hiroshima's buildings were destroyed.

Three days after the atom bomb was dropped on Hiroshima, a second one was dropped on the city of Nagasaki by a bomber plane called Bockscar. A further 74,000 people, at least, were killed. The Japanese Emperor, Hirohito, announced that Japan would surrender on 15 August. They formally signed a surrender agreement on 2 September.

This brought World War Two to an end.

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Find out about World War Two with BBC Bitesize History. For students between the ages of 11 and 14.

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"Kerry's Visit to Hiroshima Bomb Site could Pave the Way for Obama's Trip" by Bloomberg News

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"Kerry's Visit to Hiroshima Bomb Site could Pave the Way for Obama's Trip" by Bloomberg News

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Newsela | Instructional Content Platform

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Newsela is an Instructional Content Platform that supercharges reading engagement and learning in every subject.

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DK Find Out! | Fun Facts for Kids on Animals, Earth, History and more!

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Visit DK Find Out! to learn about dinosaurs, space, animals, nature & more. Fun learning activities for kids with videos, quizzes & galleries at DKFindOut.com

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"Ingeniously Charting the Horrifying Power of Today's Nuclear Bombs" by Mark Wilson

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"Ingeniously Charting the Horrifying Power of Today's Nuclear Bombs" by Mark Wilson

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"Revealed: The Most Powerful Nuclear Bomb Ever" by Paul Richard Huard

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"Revealed: The Most Powerful Nuclear Bomb Ever" by Paul Richard Huard

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China's military is rising. Russia is resurgent and developing weapons platforms that keep U.S. military planners up at night. North Korea's nuclear weapons and missile arsenal is getting more powerful by the day. Here in the Buzz, we plan to cover the most important national security, military, and defense topics of the day.

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"What You Need to Know About North Korea and its Nuclear Program" by History.com

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"What You Need to Know About North Korea and its Nuclear Program" by History.com

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What You Need to Know About North Korea & Its Nuclear Program | HISTORY

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Get a primer on the enigmatic nation and why it’s fueling international fears with its aggressive nuclear program.

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Animation shows the Deadly Evolution of Nuclear Weapons

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Animation shows the Deadly Evolution of Nuclear Weapons

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Animation shows the deadly evolution of nuclear weapons

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"Explaining Nuclear Energy for Kids" by The Washington Post

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"Explaining Nuclear Energy for Kids" by The Washington Post

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The earthquake and tsunami that hit Japan last week killed thousands of people and caused incredible damage to homes, schools, roads and office buildings. But the damage to the Fukushima Daiichi nuclear power plant and another nearby plant has put words such as radiation, nuclear reactors and fuel rods on the front page of the newspaper and all over the Internet and television. KidsPost answers some questions you might have about nuclear energy and what's happening in Japan.

What is nuclear energy?

It's the energy in the center (or nucleus) of an atom. Atoms make up everything in the universe and are held together with great force. In a process called fission, atoms are broken apart, and the energy released can be used to generate electricity at power plants, including the one in Japan that was damaged. Atoms of uranium, a common element that can be mined from the Earth, are used in nuclear reactions. In fission, a tiny particle called a neutron hits a uranium atom; the atom splits, releasing more neutrons and generating a chain reaction. That reaction releases huge amounts of energy. That energy can boil water to create steam, which in turn causes turbines to spin, generating electricity in a power plant.

What is a nuclear reactor?

A nuclear reactor is the device in a power plant where fission takes place. Pieces of uranium about the size of your fingertip get stacked up in 12-foot-long metal tubes, called rods. Bunches of rods form the core of the reactor.

So what happened in Japan?

Rods are normally kept under water, which keeps the reactor core cool. When the earthquake hit last Friday, the entire electrical grid went down, just as it can here when we have an ice storm. The nuclear plant switched to a backup system of generators. But an hour after the earthquake, the tsunami hit the plant, knocking out the generators. Backup batteries lasted only eight hours. Without power, the water couldn't circulate and began to boil away, allowing the rods to get hot. The inability to keep cooling water on the fuel rods led to explosions and fires. Those events have sent radioactive elements into the air. High levels of radiation can be dangerous, even deadly. Close to the reactors, the radition levels have gone up and down. About 50 workers trying to fix the problem are risking their lives to save their fellow citizens.

Are people getting sick now?

No. People within 19 miles of the plant have been told to stay indoors. There is medicine that can treat the effects of radiation sickness, but it has not been given to people yet.

What will happen next?

Nobody knows for sure. If there isn't water available to keep the fuel rods cool, the fingertip-size pellets can melt, like candles. This melting damages the core, which could lead to the release of more radioactive gases.

Is nuclear power safe?

That question has been asked for many years, and you will hear much more debate about it now because of the events in Japan. Nuclear power is very efficient. For example, one of those small uranium pellets can produce as much electricity as 150 gallons of oil. Many people see nuclear power as an alternative energy source. The situation at the Japanese reactors will have people talking about developing other power sources, including solar and wind.

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The earthquake and tsunami that hit Japan killed thousands of people and caused incredible damage. But the damage to the Fukushima Daiichi nuclear power plant has put words like radiation, nuclear reactors and fuel rods on the front page of the newspaper KidsPost answers some questions you might have about nuclear energy and what's happening in Japan.

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The U.S. had been at war with Japan since the Japanese air attack on Pearl Harbor on December 7, 1941, the day Japan also bombed Manila and took control of the Philippines. By mid-1942, Japanese forces had gained control of all East Asia, most of Southeast Asia, and half the Pacific area-altogether, approximately 1/6 of the earth's surface.

Thus, no offensive bombing of Japan proper could be launched until Japanese island bases in the Pacific could be taken and airfields built to accommodate the large B-29s. Except for a daring raid from China on western Japan in April 1942, Japan's skies remained free of U.S. bombers until June 1944. And Japan's major cities-Tokyo, Nagoya, Osaka, etc.-were still out of range from the Pacific-based bombers.

Meanwhile, from 1942 the U.S. pursued a radically new wartime course: development of a bomb using radioactive materials with explosive force and long-term effects far beyond anything yet known or experienced. The overall effort was named the Manhattan Project.

This project for developing the world's first atomic weapons began on a $2 million budget, with a twin project to build 2,000 of the B-29 superfortress bombers at an eventual cost of $3 billion-at the time, the largest-ever U.S. military budgets.

By early 1945, however, a major U.S. naval victory at Midway Island opened the way to U.S. control of the Marianna Islands of Guam, Saipan, and Tinian, only 1,300 miles from Tokyo-that is, close enough for the B-29s to reach Japan proper and return. Soon the largest-ever military airfields were constructed on these islands.

The B-29 was first used for day-time, high-altitude precision bombing of Germany's munitions industries. But for Japan, Gen. Curtis Le May changed from daytime, high-altitude precision raids with high-explosive bombs to low-altitude, nighttime, carpet-bombing with thousands of incendiary (fire) bombs.

Opening round: Tokyo, Nagoya, Osaka, Kobe

Throughout the night of March 9-10, 1945, flying in streams 400-miles long, a fleet of 334 B-29s fire-bombed central Tokyo for nearly three hours. Within 30 minutes of the first bomb, fires were burning out of control, embroiling the city's center in a firestorm with temperatures reaching 1,000° C (1,899° F), hot enough to cause water to boil in canals and fire-safety cisterns. Over 100,000 people-men, women, and children-perished and a million were injured, 41,000 seriously. Another million were made homeless in the scorched capital wasteland.

The Tokyo raid was followed by similar bombings of Nagoya (March 11), Osaka (March 13), and Kobe (March 16). Thus, in eight days, with 1,600 sorties, LeMay's air force burned out 32 square miles of the centers of Japan four largest cities, killing at least 150,000 people, though probably tens of thousands more. In April, LeMay wrote privately to his commanding general, "I consider that for the first time, strategic air bombardment (shows) that destruction of Japan's ability to wage war lies within the capability of this command." LeMay had found, says historian Richard Rhodes, a method "whereby the Air Force might end the Pacific War without (an) invasion."

These four raids initiated a five-month bombing of Japan's main islands. Waves of B-29s destroyed over half the total area of 66 urban centers, reducing 178 square miles to ashes. This March-July fire-bombing campaign is estimated to have taken more civilian lives than the half-million killed during five years of Allied bombing of Germany.

Meantime, by spring of 1945, U.S. submarines had destroyed Japan's merchant marine, and isolated the country by mining its harbors and coastal waters. Thus, by early summer, virtually all shipping, manufacturing, transportation, and food distribution had ground to a halt.

In such dire circumstances, one faction of Japan's central war council pushed for surrender, while a "fight to the finish" faction resisted. Meantime, the U.S. was readying a knockout punch with a new weapon of unprecedented power. Just one such bomb would surpass all the incendiary bombing of Tokyo.

TIMETABLE: Fire-bombing of Japan, March 9-10 and July 1 to August 14, 1945

B-29s (no.)

Cities bombed (I = incendiaries; HE = high explosives; M = mines)

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The U.S. had been at war with Japan since the Japanese air attack on Pearl Harbor on December 7, 1941, the day Japan also bombed Manila and took control of the Philippines. By mid-1942, Japanese forces had gained control of all East Asia, most of Southeast Asia, and half the Pacific area-altogether, approximately 1/6 of the earth's surface.

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The First Atomic Bombs: "Little Boy" and "Fat Man"

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The First Atomic Bombs: "Little Boy" and "Fat Man"

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THE FIRST ATOMIC BOMBS: "Little Boy"and "Fat Man"

There were actually two new bombs, one using uranium, the other plutonium, with different triggering devices for each. The main research and production sites were Los Alamos, New Mexico; Hanford, Washington; and Oak Ridge, Tennessee. The entire project operated under top secrecy, mobilizing top scientists and engineers, and at unprecedented high costs.

The Hiroshima bomb

Nicknamed "Little Boy"(for President Franklin Roosevelt), the bomb's size was 3 meters in length by 0.7 meter in diameter, using uranium 235 as its critical material. Inside a shortened smooth-bore 76.2 mm (3 in.) naval gun, a subcritical projectile of U-235 was fired at a subcritical target of U-235. At the moment of impact, a supercritical mass was formed, triggering a nuclear chain reaction, or atomic explosion. The gun barrel and heavy casing gave it a weight of over four metric tons (8,900 lbs). The subcritical material was an alloy called Oralloy, a code named derived from the secret laboratory at Oak Ridge, Tennessee, where it was fabricated.

For use in the gun device, the fissile materials had to be made into geometric shapes capable of withstanding the violence of being shot down the gun's tube, then stoipped abruptly at the target, and held together long enough to detonate.

The Nagasaki bomb

Nicknamed "Fat Man" (for England's Prime Minister Winston Churchill), this bomb had a core of plutonium 239, was 3.5 meters in length by 1.5 meters in diameter, and it weighed 4.5 tons. Its plutonium core was surrounded by 64 explosive charges arranged in an inner and outer shell. The explosive charges were fabricated in geometrical shapes in a configuration similar to a soccer ball-an extremely difficult and demanding procedure. When the two shells were detonated, the shockwave slammed into a tamper surrounding the plutonium nucleus, causing a rapid increase in density that compressed the slightly sub-critical plutonium core, rapidly increasing its density, making it supercritical, thus exploding in a nuclear chain reaction.

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There were actually two new bombs, one using uranium, the other plutonium, with different triggering devices for each. The main research and production sites were Los Alamos, New Mexico; Hanford, Washington; and Oak Ridge, Tennessee. The entire project operated under top secrecy, mobilizing top scientists and engineers, and at unprecedented high costs.

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Major energy forms

The major explosive energy forms that dominate research and reports on the atomic bombings are three:

Fireball: air absorbs heat, swells to a fireball with a 50-ft. radius and a temperature of 300,000 degrees C.

Shock Wave + Air Blast: 50% of total energy

Radioactivity: two kinds. initial radiation (explained above), andinduced radiation (also called "residual radiation").

Of these three energy forms, the most radically different, and most deadly over time, was the high level of radioactivity.

A deadly new threat: radioactivity

1. "Black rain"

The Hiroshima and Nagasaki explosions yielded some 200 different kinds of radioactive isotopes, that is, nuclear fission particles of uranium and plutonium that escaped fission. Following the explosions, these and other materials irradiated by neutrons from the bomb, were carried high into the atmosphere.

The mixing of enormous amounts of airborne irradiated materials combined with heat and thermal currents from the firestorms led to rainfall in both cities within 30-40 minutes of the bombings. As the fallout particles were mixed with carbon residue from citywide fires, the result was the awesome-and injurious-"black rain."

This "black rain" reached ground level as sticky, dark, dangerously radioactive water. It not only stained skin, clothing, and buildings, but also was ingested by breathing and by consumption of contaminated food or water, causing radiation poisoning.

2. Initial radiation from the bombs

About 3% of the Hiroshima and Nagasaki bombs' energy was spent in generating ionizing radiation -high-energy particles and rays with enough energy to "ionize" neutral atoms, i.e., strip electrons away from them. Some of this ionized radiation was absorbed by the air, but neutrons (electrically neutral sub-atomic particles) and gamma and X-rays (extremely high energy forms of light) did reach the ground, and these rays damaged exposed living tissues. Close to ground zero of both explosions, dosages were high enough to be immediately lethal for persons not already killed by flash, blast, or fire.

3. Induced radioactivity

Initial bursts of radiation from the two bombs also created induced or residual radioactivity. Soil and other materials were irradiated in the blast areas. Absorption of "slow neutrons" by all kinds of substances caused the creation of new isotopes that then emitted ionizing radiation.

Japanese physicists examining the areas near ground zero in Hiroshima found unusually high levels of radioactivity in the soil, in the bones of a horse, and even in the sulphur content of electrical insulators on telephone poles. Eventually, a variety of unusual radioactive elements were found in soil, roofing tiles, asphalt, and concrete near ground zero in the two cities. There were many instances of radiation effects on animals and plants.

4. Radioactivity and living tissue

Living tissue may be exposed to ionizing radiation directly (emitted by explosion) or by exposure to, or ingestion of, fallout matter that emits residual radiation. The danger is the same either way.

Key: Ionizing radiation transforms a neutral atom into a charged atom that may bond to another atom, altering (i) the structure of the original molecule, (ii) the way it reacts chemically, and (iii) the function it performs when part of a living organism. The altered molecules may act as poisons, hindering the normal functions of the cells of which they are a part.

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The major explosive energy forms that dominate research and reports on the atomic bombings are three: Fireball: air absorbs heat, swells to a fireball with a 50-ft. radius and a temperature of 300,000 degrees C. Shock Wave + Air Blast: 50% of total energy Radioactivity: two kinds.

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Major population groupings

1. Persons present in Hiroshima or Nagasaki at bombing time. Of the regular resident population, many children and older persons had been previously evacuated, while certain outsiders were working in the cities on their specific bombing days. Overall, the estimated "physically present" population of Hiroshima on August 6 was 340,000-350,000. Nagasaki's estimated "physically present" population on August 9 was 90,000-120,000.

2. Early entrants into both cities following the bombings, mainly soldiers, firefighters, medical workers, and other helping personnel.

3. Persons who suffered radiation injuries in the areas surrounding the two bombed cities.

Almost all persons in the above groupings, young or old, also fell into one of the following groups: (1) broken families; (2) A-bomb orphans; (3) orphaned elderly.

Hiroshima

Of the city's 298 medical doctors, 270 (90%) became A-bomb victims. Casualty rates among pharmacists, nurses, and other medical professionals ranged between 80% and 93%. Eighteen emergency hospitals and 32 first-aid clinics were destroyed, and most of the workers needed to restore these health facilities were killed or injured. Nearby army medical facilities were also mostly destroyed.

In sum, approximately 90% of all medical personnel were dead or disabled, and remaining medical facilities were thrown into great disrepair and confusion.
All citizens faced desperate conditions; the young and old, all the more so.

Nagasaki

In the 2-km zone of total destruction around ground zero in Nagasaki's Urakami valley, the city's chief medical facilities were destroyed. These included Nagasaki Medical University and its related hospital, the Urakami branch of Mitsubishi Hospital, Urakami First Hospital, and some other smaller health care institutions.

Of the 70 or so doctors in private practice in the city, twenty were dead and twenty more seriously wounded; only 30 were available to help the mass of A-bomb victims.

As a major port city, Nagasaki was surrounded by various naval installations. Medical personnel from several naval hospitals (Isahaya, Sasebo, Omura, and other places) came with support personnel to give assistance, making the overall situation somewhat better than in Hiroshima.

Even so, food, clothing, medicine, and other relief supplies in Nagasaki were, as in Hiroshima, extremely scarce. Moreover, heavy rains hit both cities in September, making the struggle to survive desperately difficult and miserable.

Local ability to mobilize health care personnel and restore medical facilities was severely hampered by the overall loss of non-military economic wealth (65 billion yen nationwide). Of this total, Hiroshima (884 million yen) and Nagasaki (380 million yen) together suffered over 2% of the national total.

Political restraints on recovery

On top of the enormous physical, medical, and social damages imposed on Japan by the two atomic bombings, the Supreme Commander of the Allied Occupation (SCAP) imposed another onerous handicap: censorship. Formally termed the Press Code, officially issued by the Occupation GHQ on September 19, 1945, it prohibited the publication of all reports and studies of A-bomb damages, including medical and scientific studies of all injuries and losses suffered by A-bomb victims in both Hiroshima and Nagasaki, whether in newspapers, magazines, scholarly journals, books, or other public means. Thus the A-bombed citizens struggled with ignorance of the many medical and social aspects of the decimated lives.

There were minor exceptions. The Hiroshima-based magazine, Chugoku Bunka, devoted its initial issue (March 10, 1946) to A-bomb damages. A Manhattan Project team published its report, The Atomic Bombings of Hiroshima and Nagasaki on June 29, 1946. And the U.S. Strategic Bombing Survey Team completed its report, The Effects of the Air Attack on the Cities of Hiroshima and Nagasaki the following day. These official documents, however, were printed in English and, in any case, did not touch deeply on the sufferings of the two A-bombed cities.

Most importantly, serious research on the extent and gravity of A-bomb damages and injuries could not be publicly printed and distributed by any Japanese persons or organizations, thus handicapping the surviving medical personnel trying to heal and assuage the thousands of A-bomb victims. The most revealing item, perhaps, is that the Japanese characters for "atomic bomb" ( genshi bakudan, or the short form, genbaku) could not even be used in public print. This applied to all forms: newspapers, magazines, books, public bulletins, and of course, movies.

Cameramen of the Japanese movie firm Nippon Eiga-sha were arrested by American MPs in Nagasaki on October 17, 1945, and two days later the photographing of A-bomb scenes was prohibited. A formal prohibition was issued by GHQ on December 12. It would be almost seven years later until, after the Occupation ended, the weekly magazine Asahi Gurafu ( Asahi Graph) filled an entire issue with heretofore unpublicized photographs of A-bomb damages and victims-the first A-bomb-related photos to be published in the postwar era.

One of the most moving instances of resistance to the Press Code was a small volume of tanka (a Japanese verse form of 31 syllables), penned by a hibakusha poet named Shinoe Shoda in Hiroshima. Titled Sange, it decried the cruelty of the bomb. As publication of all A-bomb-related materials was strictly banned, she took her manuscript to Tadao Nakamura, a clerk in the printing shop of a Hiroshima prison, who mimeographed 150 copies in December 1947. Shoda distributed copies to other hibakusha, all at her own expense and, of course, without SCAP permission. A hand-written copy of Sange was later donated to the Hiroshima Peace Cultural Foundation.

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Persons present in Hiroshima or Nagasaki at bombing time. Of the regular resident population, many children and older persons had been previously evacuated, while certain outsiders were working in the cities on their specific bombing days. Overall, the estimated "physically present" population of Hiroshima on August 6 was 340,000-350,000.

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AtomicBombMuseum.org - The Pursuit of Peace

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The postwar Japanese experience has been a counterpoint struggle between the persistent advocacy of a peaceful world, as evident in huge public rallies and in the many levels of personal involvement in peace studies and promotion, on the one hand, and the reckless increase in…

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Conflict with North Korea: "Nuclear Weapons" from Grolier's The New Book of Knowledge

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Conflict with North Korea: "Nuclear Weapons" from Grolier's The New Book of Knowledge

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Dannen.com > Leo Szilard Online > Atomic Bomb: Decision

On August 6 and 9, 1945, the cities of Hiroshima and Nagasaki were destroyed by the first atomic bombs used in warfare.

Documents on the decision to use the atomic bomb are reproduced here in full-text form, and many also as images. All transcriptions are by Gene Dannen. In most cases, the original documents are in the U.S. National Archives. Other aspects of the decision are shown from accounts by the participants. This page was new May 29, 1995, and it was last updated January 25, 2018.

International Law - Bombing of Civilians - At the beginning of World War II, the bombing of civilians was regarded as a barbaric act. As the war continued, however, all sides abandoned previous restraints. But international law has always distinguished between civilians and combatants. Legal context to the decision, from a variety of international treaties and the 1996 World Court opinion.
Target Committee, Los Alamos, May 10-11, 1945 - Minutes of the Target Committee, meeting in the office of J. Robert Oppenheimer, as they decided the best use of the "gadget."
The Franck Report, June 11, 1945 - The Franck Report, written by a seven-man panel of scientists at the University of Chicago, urged that the bomb be demonstrated "before the eyes of representatives of all United Nations, on the desert or a barren island."
Scientific Panel, June 16, 1945 - Despite the arguments against using the bomb made by the Franck Report, a panel composed of Oppenheimer, Fermi, Compton, and Lawrence found "no acceptable alternative to direct military use."
Bard Memorandum, June 27, 1945 - Undersecretary of the Navy Ralph A. Bard wrote that use of the bomb without warning was contrary to "the position of the United States as a great humanitarian nation," especially since Japan seemed close to surrender.
Setting the Test Date, July 2, 1945 - President Truman had delayed his meeting with Stalin until the atomic bomb could be tested. On July 2, General Groves told Robert Oppenheimer that the test date was being set by "the upper crust."
Szilard Petition, first version, July 3, 1945 - The first version of Leo Szilard's petition called atomic bombs "a means for the ruthless annihilation of cities." It asked the President "to rule that the United States shall not, in the present phase of the war, resort to the use of atomic bombs."
Petition cover letter, July 4, 1945 - Szilard sent copies of the July 3 version of his petition to colleagues at Oak Ridge and Los Alamos. This cover letter discussed the need for scientists to take a moral stand on the use of the bomb.
Groves Seeks Evidence, July 4, 1945 - As Szilard circulated his petition, General Groves sought ways to take action against him. On July 4, 1945, Groves wrote to Lord Cherwell, Winston Churchill's science advisor.
Oak Ridge petition, July 13, 1945 - The first version of Szilard's petition inspired a similar petition at the Manhattan Project laboratory at Oak Ridge, Tennessee. The names of the 18 signers are included.
Oak Ridge petition, mid-July 1945 - Another petition at Oak Ridge called for the power of the bomb to be "adequately described and demonstrated" before use. The names of the 67 signers are included.
Trinity Test, July 16, 1945 - Radiation Monitoring - The test of the atomic bomb in the New Mexico desert on July 16 was a spectacular success. This report by Manhattan Project Chief of Medical Section Stafford Warren shows that radioactive fallout from the test was an important concern.
Trinity Test, July 16, 1945 - Eyewitness Accounts - Even 32 kilometers (20 miles) away, scientists felt the heat of the explosion on exposed skin. Declassified eyewitness accounts of the Trinity test by Luis Alvarez, Enrico Fermi, Philip Morrison, Robert Serber, Victor Weisskopf, and others.
Szilard Petition, July 17, 1945 - Leo Szilard, and 69 co-signers at the Manhattan Project "Metallurgical Laboratory" in Chicago, petitioned the President of the United States. The names and positions of the signers are included.
Szilard Petition, July 17, 1945 - Full-color Image - See Szilard's petition. Though it contained no secret information, the petition was not declassified until 1957.
Truman Tells Stalin, July 24, 1945 - At the Potsdam Conference in defeated Germany, President Truman told Stalin only that the U.S. "had a new weapon of unusual destructive force." What did Truman say, and what did Stalin understand? Seven eyewitness accounts.
Truman Diary, July 25, 1945 - President Truman told his diary that he had ordered the bomb dropped on a "purely military" target, so that "military objectives and soldiers and sailors are the target and not women and children."
Official Bombing Order, July 25, 1945 - The bombing order issued to General Spaatz made no mention of targeting military objectives or sparing civilians. The cities themselves were the targets.
Bomb Production Schedule, July 30, 1945 - The Manhattan Project was designed to make far more than a few bombs. The production rate of 3 bombs per month in August was expected to rise to 5 bombs/month in November, and 7 bombs/month in December.
Groves-Oppenheimer transcript, August 6, 1945 - General Groves informed Robert Oppenheimer of the Hiroshima bombing. Transcript of telephone conversation.
Truman radio speech, August 9, 1945 (excerpt) - In his radio speech to the nation on August 9, President Truman called Hiroshima "a military base." This is an audio file. Hear Truman say it. Or read the full text of that paragraph.
Truman Revokes Bombing Order, August 10, 1945 - Horrified by reports of the enormous casualties in Hiroshima and Nagasaki, Truman ordered the atomic bombing stopped.
Leo Szilard, Interview: "President Truman Did Not Understand" - A 1960 interview with Leo Szilard about the use of the bomb, reprinted by permission from U.S. News & World Report.

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Cool Central Site of the Day - August 6, 1998

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Copyright © 1995-2018 Gene Dannen
Created May 29, 1995 Last modified January 25, 2018
URL: http://www.dannen.com/decision/index.html
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Dannen.com > Leo Szilard Online > Atomic Bomb: Decision On August 6 and 9, 1945, the cities of Hiroshima and Nagasaki were destroyed by the first atomic bombs used in warfare. Documents on the decision to use the atomic bomb are reproduced here in full-text form, and many also as images.

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On August 6, 1945, after 44 months of increasingly brutal fighting in the Pacific, an American B-29 bomber loaded with a devastating new weapon appeared in the sky over Hiroshima, Japan. Minutes later, that new weapon-a bomb that released its enormous destructive energy by splitting uranium atoms to create a chain reaction-detonated in the sky, killing some 70,000 Japanese civilians instantly and leveling the city. Three days later, the U.S. dropped a second atomic bomb over the city of Nagasaki, with similarly devastating results. The following week, Japan's emperor addressed his country over the radio to announce the decision to surrender. World War II had finally come to its dramatic conclusion. The decision to employ atomic weapons against Japan remains a controversial chapter in American history. Even before the new President Harry S. Truman finalized his decision to use the bombs, members of the President's inner circle grappled with the specifics of the decision to drop the new weapon. Their concerns revolved around a cluster of related issues: whether the use of the technology was necessary to defeat an already crippled Japan; whether a similar outcome could be effected without using the bomb against civilian targets; whether the detonation of a second bomb days after the first, before Japan had time to formulate its response, was justified; and what effect the demonstration of the bomb's devastating power would have on postwar diplomacy, particularly on America's uneasy wartime alliance with the Soviet Union.

Controversy is Alive and Well

The ongoing struggle to present the history of the atomic bombings in a balanced and accurate manner is an interesting story in its own right, and one that has occasionally generated an enormous amount of controversy. In 1995, anticipating the 50th anniversary of the end of World War II, the Smithsonian's National Air and Space Museum planned a display around the fuselage of the Enola Gay, the aircraft that dropped the first bomb, for its museum on the National Mall. That exhibit would place the invention of atomic weapons and the decision to use them against civilian targets in the context of World War II and the Cold War, provoking broader questions about the morality of strategic bombing and nuclear arms in general.

The ongoing struggle to present the history of the atomic bombings in a balanced and accurate manner is an interesting story in its own right. . . .

The design for the exhibit quickly triggered an avalanche of controversy. Critics charged that it offered a too-sympathetic portrayal of the Japanese enemy, and that its focus on the children and elderly victims of the bombings at Hiroshima and Nagasaki encouraged visitors to question the necessity and morality of the weapons. As originally written, those critics alleged, the exhibit forwarded an anti-American interpretation of events surrounding the bombs' use. That such a message was to appear in a national museum amplified the frustrations of critics (especially veterans' groups), who believed that the exhibit should not lead museumgoers to question the decision to drop the bomb or to portray the Pacific war in morally neutral terms. In place of the original exhibit, veterans' organizations offered a replacement exhibit with a very different message. Their proposed exhibit portrayed the development of the atomic weapons as a triumph of American technical ingenuity, and the use of both bombs as an act that saved lives-the lives of American soldiers who would otherwise have had to invade the Japanese home islands, and the lives of thousands of Japanese who would, it was assumed, have fought and died with fanatic determination opposing such an invasion. The revised exhibit removed the questioning tone of the original, replacing it with more certainty: the use of the bombs, it argued, was both necessary and justified.

When the controversy died down, the Smithsonian elected not to stage any exhibit of the aircraft fuselage.

The historians who produced the original exhibit stood accused of historical revisionism by their critics, of needlessly complicating patriotic consensus with moral concerns. The fallout from the controversy led to loud, public debate in the halls of Congress and, ultimately, to the resignation of several leaders at the museum. When the controversy died down, the Smithsonian elected not to stage any exhibit of the aircraft fuselage. Years later, the plane went on display at the Smithsonian's Udvar-Hazy Center outside Washington, DC, where it resides now, accompanied by a brief placard detailing its technical specifications.

Because the use of the atomic weapons evokes such passionate responses from Americans-from those who believe that the use of the bombs was wholly justified to those who believe that their use was criminal, and the many people who fall somewhere in between-it is a particularly difficult topic for textbooks to discuss. In order to avoid a potentially treacherous debate, textbooks have often adopted a set of compromises that describe the end of the war but avoid or omit some of the most difficult parts of the conversation. A 1947 history textbook, produced just two years after the bombings did just this, sidestepping the controversy by presenting the story at a distance and refraining from interpretation or discussion of civilian casualties: "The United States unveiled its newest weapon, demonstrating twice-first at Hiroshima and then at Nagasaki-that a good-sized city could almost be erased from the map in one blinding flash. Confronted by this combination of forces, Japan surrendered August 14."

"If the war dragged on and Americans had to invade Japan, it might cost a million lives...life for life, the odds were that [the atomic bomb] would cost less."

Later textbooks made other compromises. The 2005 textbook A History of the United States adopts a familiar tone, arguing that President Truman based his decision to drop the bomb mainly on a complex calculus of the cost in human lives if the war were to continue: "Should the United States use the atomic bomb? No one knew how long Japan would hold out." That uncertainty forced American planners to assume the worst: "If the war dragged on and Americans had to invade Japan, it might cost a million lives. The atomic bomb, President Truman knew, might kill many thousands of innocent Japanese. But life for life, the odds were that it would cost less." A 2006 textbook, The Americans, suggests that the decision to drop the bomb occurred largely outside moral concerns: "Should the Allies use the bomb to bring an end to the war? Truman did not hesitate. On July 25, 1945, he ordered the military to make final plans for dropping two atomic bombs on Japan." The paragraph on the decision concludes with a compelling quote from the President himself: "Let there be no mistake about it. I regarded the bomb as a military weapon and never had any doubt it should be used." Other recent textbooks have labored to present this often-contentious topic in a more nuanced manner. The 2007 textbook American Anthem describes the decision-making process as an involved one, observing "Truman formed a group to advise him about using the bomb. This group debated where the bomb should be used and whether the Japanese should be warned. After carefully considering all the options, Truman decided to drop the bomb on a Japanese city. There would be no warning." The carefully written passage does not suggest that the question of whether to use the bomb against civilian targets was part of the debate; it describes the inquiry as focused on where to drop the bomb and whether a warning would precede its use. More recent textbooks often offer viewpoints from other perspectives-including Japanese civilians, who suffered the legacy of atomic fallout for decades after the original explosion-from a morally neutral stance, inviting (or directly asking) readers to make their own judgments. Besides offering a description of Truman's decision-making process, the American Anthem textbook includes a passage of equivalent length that describes the destruction on the ground, anchored by a quote from a survivor of the Hiroshima bomb. It also features a "Counterpoints" section that contrasts a quote from Secretary of War Henry Stimson supporting the bomb's use with one from Leo Szilard, an atomic physicist, characterizing the use of the bombs against Japan as "one of the greatest blunders of history."

What the Documents Reveal

A discussion that focuses primarily on the need to employ the bomb in order to save lives-the lives of Japanese civilians as well as those of American soldiers-is incomplete. In fact, as the documentary record shows, there was a good deal of debate over the use of the weapons during the summer of 1945, much of which focused on more complex issues than the lives that would be saved or lost in ending the war.

A discussion that focuses primarily on the need to employ the bomb in order to save lives-the lives of Japanese civilians as well as those of American soldiers-is incomplete.

Dwight D. Eisenhower, the Supreme Commander of the Allied forces in Europe and one of the architects of the successful campaign against Germany, was one of the dissenters. After the war, Eisenhower recalled his position in 1945, asserting that "Japan was defeated and... dropping the bomb was completely unnecessary." Eisenhower's objection was, in part, a moral one; as he noted, "I thought our country should avoid shocking world opinion by the use of a weapon whose employment was, I thought, no longer mandatory as a measure to save American lives. It was my belief that Japan was, at that very moment, seeking some way to surrender with a minimum loss of 'face.'" Eisenhower recalled that his objection found an unreceptive audience with Secretary of War Henry Stimson. In Eisenhower's own words, Stimson was "deeply perturbed by my attitude, almost angrily refuting the reasons I gave for my quick conclusions." (In a separate document, Stimson himself concurred with Eisenhower's conclusion that there was little active American attempt to respond to Japan's peace feelers to prevent the use of the atomic weapons: "No effort was made, and none was seriously considered, to achieve surrender merely in order not to have to use the bomb.") The year after the Japanese surrender, the U.S. government released its own Strategic Bombing Survey, an effort to assess the effectiveness of dropping bombs on civilian populations, including the firebombs used in Europe and the Pacific, and the atomic weapons detonated over Hiroshima and Tokyo (see Primary Source U.S. Strategic Bombing Survey [1946]). Its findings suggested that the bombs were largely superfluous, and that Japan's surrender was all but guaranteed even without the threat of invasion. "Based on a detailed investigation of all the facts," the SBS concluded, "and supported by the testimony of the surviving Japanese leaders involved, it is the Survey's opinion that . . . Japan would have surrendered even if the atomic bombs had not been dropped, even if Russia had not entered the war, and even if no invasion had been planned or contemplated." Though firm in its assertions, the SBS received widespread criticism from many quarters for drawing conclusions far beyond the available evidence. (Many critics noted, rightly, that the SBS was itself hardly a disinterested document, since it was produced by an organization with an interest in emphasizing the effectiveness of conventional airpower.)

The compromises 21st-century textbooks have struck appear understandable if not necessary.

The Strategic Bombing Survey's conclusions highlight another important factor in the decision to employ the bombs against Japan: the message such a display would send to Josef Stalin. Uneasy allies in the war against Germany, Russian forces joined the war in Japan in August 1945. Contemporary observers noted that the demonstration of the deadly new weapon's considerable might had the additional effect of warning Stalin that the U.S. would exercise considerable power in the postwar period. Furthermore, dropping two bombs only days apart had the added benefit of convincing the Russians that the U.S. possessed a formidable supply of the new weapons; when in fact, the U.S. nuclear arsenal was entirely depleted after the two attacks on Japan. A survey of primary sources from the summer of 1945 and the months afterward reveals a variety of opinions, arguments, and justifications regarding the use of atomic weapons. Embracing the variety of opinions while also presenting a narrative that depicts the decision and its effects from multiple perspectives is a near-impossible task. Given how controversial the story of Hiroshima and Nagasaki has proved to be, the compromises 21st-century textbooks have struck appear understandable if not necessary.

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On August 6, 1945, after 44 months of increasingly brutal fighting in the Pacific, an American B-29 bomber loaded with a devastating new weapon appeared in the sky over Hiroshima, Japan. Minutes later, that new weapon-a bomb that released its enormous destructive energy by splitting uranium atoms to create a chain reaction-detonated in the sky, killing some 70,000 Japanese civilians instantly and leveling the city.

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The Decision to Drop the Atomic Bomb | Harry S. Truman

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The Bombing of Hiroshima and Nagasaki | Historical Documents

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This collection of documents chronicles the atomic bombings of Hiroshima and Nagasaki. Available documents include: White House Press Release on Hiroshima, Eyewitness Account of Atomic Bomb Over Nagasaki, Conversations at Farm Hall, Eyewitness Account of Hiroshima By Father John A. Siemes, The Voice…

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The detonation of the first atomic bomb in July 1945 started the Atomic Age, an era in which the fear of nuclear attack and the promise of nuclear power pervaded American culture. Less than a month later, two atomic bombs were dropped on Japan, killing at least 129,000 Japanese, and precipitating the end of World War II in the Pacific. The bombs caused some to see the possibilities for harnessing the power of atomic energy for good, while many feared the further development of atomic energy for war. The Cold War of the 1950s and 1960s between the US and the Soviet Union was largely forged by this fear of nuclear war. Each nation raced to develop more and more powerful bombs pointed at one another's shores. The resources here, including letters, photographs, official documents, and film, represent various aspects and visions of the Atomic Age.

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The detonation of the first atomic bomb in July 1945 started the Atomic Age, an era in which the fear of nuclear attack and the promise of nuclear power pervaded American culture. Less than a month later, two atomic bombs were dropped on Japan, killing at least 129,000 Japanese, and precipitating the end of World War II in the Pacific.

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A film showing the destruction of the atomic bomb in Hiroshima

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A film showing the destruction of the atomic bomb in Hiroshima

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Citation Information

"Effect of Atomic Bomb on Hiroshima and Nagasaki," Digital Public Library of America, http://dp.la/item/1a7102b3eea481f5496a2268aa6957e8.

Note: These citations are programmatically generated and may be incomplete.

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A film showing the destruction of the atomic bomb in Hiroshima.

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Citation Information "Effect of Atomic Bomb on Hiroshima and Nagasaki," Digital Public Library of America, http://dp.la/item/1a7102b3eea481f5496a2268aa6957e8. Note: These citations are programmatically generated and may be incomplete.

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"Japanese doctors said that those who had been killed by the blast itself died instantly. But presently, according to these doctors, those who had suffered only small burns found their appetite failing, their hair falling out, their gums bleeding. They developed temperatures of 104, vomited blood, and died. It was discovered that they had lost 86 percent of their white blood corpuscles. Last week the Japanese announced that the count of Hiroshima's dead had risen to 125,000." - From the article "What Ended the War," LIFE magazine, 9/17/1945

This article published in LIFE magazine was the first eye-witness account of the bombing that the American public was exposed to. The graphic description could only instill fear in the American public. This account made the public fully aware of the power and consequences of nuclear weaponry, and they became afraid about the future use of nuclear weaponry. This account could only cover the short-term effects of the atomic bomb and nuclear fallout, so the immediate fear quickly vanished and became passionate nationalism. However, once the long-term impact of dropping the atomic bomb over Japan became evident, ethical debates concerning the atomic bomb became prevalent in American politics and lay-person conversations. The public began to question governmental motives and science as a whole. Controversy swirled, and continues to swirl, around whether or not detonating the atomic bomb was a necessity in ending the war, or if it was simply a display of scientific power to set the United States apart from its enemies as a superior nation. Ultimately, first-hand accounts, such as this one, brought fear and distrust into the public sphere. This distrust and fear set the stage for cultural shifts, especially with the approach of the Cold War and scientific advancements concerning nuclear fallout.
Fallout Informational Documentary - 1955

This documentary aired in 1955, in the midst of the Cold War, as a precautionary informational video informing the general public on how to stay safe and avoid the harmful effects of nuclear fallout. As described in the video, fallout was not localized to the test site in which the nuclear weapon had been detonated, so anyone within a few hundred miles radius of the test site had to be careful to avoid nuclear fallout. Some of the safety steps explained include listening to the local radio for any updates on nearby nuclear fallout, avoiding windows and doors, using sandbags to prevent fallout from entering windows and small openings, and stocking up on supplies such as food and water in the event that nuclear fallout prevents leaving the home for extended periods of time. However, as the Cold War progressed, fears about nuclear fallout and radiation were not limited to only nuclear weapons testing as the public concern of a nuclear war grew as well. This documentary is an attempt to calm and inform the American public through small safety steps. However, nuclear fallout cannot be avoided simply by following the steps outlined in this documentary, but it gave the public a sense of control over a dangerous and scary situation. It also failed to acknowledge the true dangers that nuclear fallout can cause to people and the environment. Essentially, this documentary is nothing more than an attempt to use media to calm the fears of the American public as the Cold War waged on and the threat of nuclear war was deeply present in American culture.
Newspaper Article - 1995

As stated, this newspaper article concerns a man protesting at the Trinity Site in New Mexico where the first atomic bomb to be created was tested. A significant part of this event is that the man protesting was from Harrisburg, Pennsylvania, where one of the worst nuclear power plant meltdowns in the United States had ever occurred. The man is enraged by his personal experience with the harmful effects of nuclear radiation, and he most likely disagrees with the military action taken in Japan using nuclear weaponry. Culturally, this article exemplifies how different the American public's perspective concerning nuclear fallout has come to be. Immediately following the bombing of Hiroshima and Nagasaki, Americans were afraid of nuclear power and how it could potentially harm them, especially as the Cold War progressed following World War II. However, the negative impacts of nuclear fallout had been discovered through various methods of scientific research over time, and the American public became frustrated with both their lack of control over nuclear weapons testing, and the carelessness with which the testing was done. This article shows the public's sentiments concerning nuclear weapon use by the United States from both past and present, and the cultural shift that came along with this changing perspective.
Genes, Development, and Cancer - Edward B. Lewis, 2004
Edward B. Lewis was an American geneticist that had performed Nobel Prize winning studies on Drosophila, which founded the field of developmental genetics. During the 1950s and 1960s, he performed studies concerning the effects of nuclear radiation and nuclear fallout by examining the medical records of the survivors in Nagasaki and Hiroshima, and discovered that "health risks from radiation had been underestimated." In a specific study done in prompted by atomic tests done in Nevada in 1958, Lewis discovered that the thyroids of young children and infants was susceptible to radioiodine released during these nuclear tests. Studies in the late 1950s showed that the milk of cows that had fed on the nuclear fallout contaminated grass near the test site in Nevada contained concentrated amounts of radioiodine. Therefore, when a young child or infant had been fed the contaminated milk, the thyroid of these individuals absorbed the beta radiation from radioiodine. A subsequent study showed a significant increase in thyroid cancer among individuals who were infants or young children during the atomic bomb testing done in 1958 in Nevada. Similarly, in 1963 Lewis performed a radiologist study which found that low doses of ionizing radiation, the type of radiation found in nuclear fallout, can induce leukemia in exposed individuals. The publication of these studies stoked the public's aversion to nuclear weapons testing and development within the United States. The American public felt that the government was careless in testing these weapons within the country, where fallout could be carried for thousands of miles by jet streams, and effectively pollute the nation. The health hazards involved in nuclear detonation also resulted in a greater public fear of nuclear war during the Cold War, which resulted in a lifestyle driven by fear and distrust.

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"Japanese doctors said that those who had been killed by the blast itself died instantly. But presently, according to these doctors, those who had suffered only small burns found their appetite failing, their hair falling out, their gums bleeding. They developed temperatures of 104, vomited blood, and died.

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Harry Truman Announcing the Atomic Bombing of Hiroshima

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Harry Truman Announcing the Atomic Bombing of Hiroshima

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Primary Source: Harry Truman Announcing the Atomic Bombing of Hiroshima (1945) | United States History II

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On August 6, 1945, Harry Truman disclosed to the American public that the United States had detonated an atomic bomb over Hiroshima, Japan.

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The Atomic Bomb and the End of World War II

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The Atomic Bomb and the End of World War II

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Washington, D.C., August 4, 2020 - To mark the 75th anniversary of the atomic bombings of Hiroshima and Nagasaki in August 1945, the National Security Archive is updating and reposting one of its most popular e-books of the past 25 years.

While U.S. leaders hailed the bombings at the time and for many years afterwards for bringing the Pacific war to an end and saving untold thousands of American lives, that interpretation has since been seriously challenged. Moreover, ethical questions have shrouded the bombings which caused terrible human losses and in succeeding decades fed a nuclear arms race with the Soviet Union and now Russia and others.

Three-quarters of a century on, Hiroshima and Nagasaki remain emblematic of the dangers and human costs of warfare, specifically the use of nuclear weapons. Since these issues will be subjects of hot debate for many more years, the Archive has once again refreshed its compilation of declassified U.S. government documents and translated Japanese records that first appeared on these pages in 2005.

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Introduction
By William Burr
The 75th anniversary of the atomic bombings of Hiroshima and Nagasaki in August 1945 is an occasion for sober reflection. In Japan and elsewhere around the world, each anniversary is observed with great solemnity. The bombings were the first time that nuclear weapons had been detonated in combat operations. They caused terrible human losses and destruction at the time and more deaths and sickness in the years ahead from the radiation effects. And the U.S. bombings hastened the Soviet Union's atomic bomb project and have fed a big-power nuclear arms race to this day. Thankfully, nuclear weapons have not been exploded in war since 1945, perhaps owing to the taboo against their use shaped by the dropping of the bombs on Japan.

Along with the ethical issues involved in the use of atomic and other mass casualty weapons, why the bombs were dropped in the first place has been the subject of sometimes heated debate. As with all events in human history, interpretations vary and readings of primary sources can lead to different conclusions. Thus, the extent to which the bombings contributed to the end of World War II or the beginning of the Cold War remain live issues. A significant contested question is whether, under the weight of a U.S. blockade and massive conventional bombing, the Japanese were ready to surrender before the bombs were dropped. Also still debated is the impact of the Soviet declaration of war and invasion of Manchuria, compared to the atomic bombings, on the Japanese decision to surrender. Counterfactual issues are also disputed, for example whether there were alternatives to the atomic bombings, or would the Japanese have surrendered had a demonstration of the bomb been used to produced shock and awe. Moreover, the role of an invasion of Japan in U.S. planning remains a matter of debate, with some arguing that the bombings spared many thousands of American lives that otherwise would have been lost in an invasion.

Those and other questions will be subjects of discussion well into the indefinite future. Interested readers will continue to absorb the fascinating historical literature on the subject. Some will want to read declassified primary sources so they can further develop their own thinking about the issues. Toward that end, in 2005, at the time of the 60th anniversary of the bombings, staff at the National Security Archive compiled and scanned a significant number of declassified U.S. government documents to make them more widely available. The documents cover multiple aspects of the bombings and their context. Also included, to give a wider perspective, were translations of Japanese documents not widely available before. Since 2005, the collection has been updated. This latest iteration of the collection includes corrections, a few minor revisions, and updated footnotes to take into account recently published secondary literature.

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2015 Update

August 4, 2015 - A few months after the atomic bombings of Hiroshima and Nagasaki, General Dwight D. Eisenhower commented during a social occasion "how he had hoped that the war might have ended without our having to use the atomic bomb." This virtually unknown evidence from the diary of Robert P. Meiklejohn, an assistant to Ambassador W. Averell Harriman, published for the first time today by the National Security Archive, confirms that the future President Eisenhower had early misgivings about the first use of atomic weapons by the United States. General George C. Marshall is the only high-level official whose contemporaneous (pre-Hiroshima) doubts about using the weapons against cities are on record.

On the 70th anniversary of the bombing of Hiroshima on August 6, 1945, the National Security Archive updates its 2005 publication of the most comprehensive on-line collection of declassified U.S. government documents on the first use of the atomic bomb and the end of the war in the Pacific. This update presents previously unpublished material and translations of difficult-to-find records. Included are documents on the early stages of the U.S. atomic bomb project, Army Air Force General Curtis LeMay's report on the firebombing of Tokyo (March 1945), Secretary of War Henry Stimson's requests for modification of unconditional surrender terms, Soviet documents relating to the events, excerpts from the Robert P. Meiklejohn diaries mentioned above, and selections from the diaries of Walter J. Brown, special assistant to Secretary of State James Byrnes.

The original 2005 posting included a wide range of material, including formerly top secret "Magic" summaries of intercepted Japanese communications and the first-ever full translations from the Japanese of accounts of high level meetings and discussions in Tokyo leading to the Emperor's decision to surrender. Also documented are U.S. decisions to target Japanese cities, pre-Hiroshima petitions by scientists questioning the military use of the A-bomb, proposals for demonstrating the effects of the bomb, debates over whether to modify unconditional surrender terms, reports from the bombing missions of Hiroshima and Nagasaki, and belated top-level awareness of the radiation effects of atomic weapons.

The documents can help readers to make up their own minds about long-standing controversies such as whether the first use of atomic weapons was justified, whether President Harry S. Truman had alternatives to atomic attacks for ending the war, and what the impact of the Soviet declaration of war on Japan was. Since the 1960s, when the declassification of important sources began, historians have engaged in vigorous debate over the bomb and the end of World War II. Drawing on sources at the National Archives and the Library of Congress as well as Japanese materials, this electronic briefing book includes key documents that historians of the events have relied upon to present their findings and advance their interpretations.

The Atomic Bomb and the End of World War II: A Collection of Primary Sources

Seventy years ago this month, the United States dropped atomic bombs on Hiroshima and Nagasaki, the Soviet Union declared war on Japan, and the Japanese government surrendered to the United States and its allies. The nuclear age had truly begun with the first military use of atomic weapons. With the material that follows, the National Security Archive publishes the most comprehensive on-line collection to date of declassified U.S. government documents on the atomic bomb and the end of the war in the Pacific. Besides material from the files of the Manhattan Project, this collection includes formerly "Top Secret Ultra" summaries and translations of Japanese diplomatic cable traffic intercepted under the "Magic" program. Moreover, the collection includes for the first time translations from Japanese sources of high level meetings and discussions in Tokyo, including the conferences when Emperor Hirohito authorized the final decision to surrender.[1]

Ever since the atomic bombs were exploded over Japanese cities, historians, social scientists, journalists, World War II veterans, and ordinary citizens have engaged in intense controversy about the events of August 1945. John Hersey's Hiroshima, first published in the New Yorker in 1946 encouraged unsettled readers to question the bombings while church groups and some commentators, most prominently Norman Cousins, explicitly criticized them. Former Secretary of War Henry Stimson found the criticisms troubling and published an influential justification for the attacks in Harper's.[2] During the 1960s the availability of primary sources made historical research and writing possible and the debate became more vigorous. Historians Herbert Feis and Gar Alperovitz raised searching questions about the first use of nuclear weapons and their broader political and diplomatic implications. The controversy, especially the arguments made by Alperovitz and others about "atomic diplomacy" quickly became caught up in heated debates over Cold War "revisionism." The controversy simmered over the years with major contributions by Martin Sherwin and Barton J. Bernstein but it became explosive during the mid-1990s when curators at the National Air and Space Museum met the wrath of the Air Force Association over a proposed historical exhibit on the Enola Gay.[3] The NASM exhibit was drastically scaled-down but historians and journalist continued to engage in the debate. Alperovitz, Bernstein, and Sherwin made new contributions as did other historians, social scientists, and journalists including Richard B. Frank, Herbert Bix, Sadao Asada, Kai Bird, Robert James Maddox, Sean Malloy, Robert P. Newman, Robert S. Norris, Tsuyoshi Hagesawa, and J. Samuel Walker.[4]

The continued controversy has revolved around the following, among other, questions:

were the atomic strikes necessary primarily to avert an invasion of Japan in November 1945?

Did Truman authorize the use of atomic bombs for diplomatic-political reasons-- to intimidate the Soviets--or was his major goal to force Japan to surrender and bring the war to an early end?

If ending the war quickly was the most important motivation of Truman and his advisers to what extent did they see an "atomic diplomacy" capability as a "bonus"?

To what extent did subsequent justification for the atomic bomb exaggerate or misuse wartime estimates for U.S. casualties stemming from an invasion of Japan?

Were there alternatives to the use of the weapons? If there were, what were they and how plausible are they in retrospect? Why were alternatives not pursued?

How did the U.S. government plan to use the bombs? What concepts did war planners use to select targets? To what extent were senior officials interested in looking at alternatives to urban targets? How familiar was President Truman with the concepts that led target planners chose major cities as targets?

What did senior officials know about the effects of atomic bombs before they were first used. How much did top officials know about the radiation effects of the weapons?

Did President Truman make a decision, in a robust sense, to use the bomb or did he inherit a decision that had already been made?

Were the Japanese ready to surrender before the bombs were dropped? To what extent had Emperor Hirohito prolonged the war unnecessarily by not seizing opportunities for surrender?

If the United States had been more flexible about the demand for "unconditional surrender" by explicitly or implicitly guaranteeing a constitutional monarchy would Japan have surrendered earlier than it did?

How decisive was the atomic bombings to the Japanese decision to surrender?

Was the bombing of Nagasaki unnecessary? To the extent that the atomic bombing was critically important to the Japanese decision to surrender would it have been enough to destroy one city?

Would the Soviet declaration of war have been enough to compel Tokyo to admit defeat?

Was the dropping of the atomic bombs morally justifiable?

This compilation will not attempt to answer these questions or use primary sources to stake out positions on any of them. Nor is it an attempt to substitute for the extraordinary rich literature on the atomic bombings and the end of World War II. Nor does it include any of the interviews, documents prepared after the events, and post-World War II correspondence, etc. that participants in the debate have brought to bear in framing their arguments. Originally this collection did not include documents on the origins and development of the Manhattan Project, although this updated posting includes some significant records for context. By providing access to a broad range of U.S. and Japanese documents, mainly from the spring and summer of 1945, interested readers can see for themselves the crucial source material that scholars have used to shape narrative accounts of the historical developments and to frame their arguments about the questions that have provoked controversy over the years. To help readers who are less familiar with the debates, commentary on some of the documents will point out, although far from comprehensively, some of the ways in which they have been interpreted. With direct access to the documents, readers may develop their own answers to the questions raised above. The documents may even provoke new questions.

Contributors to the historical controversy have deployed the documents selected here to support their arguments about the first use of nuclear weapons and the end of World War II. The editor has closely reviewed the footnotes and endnotes in a variety of articles and books and selected documents cited by participants on the various sides of the controversy.[5] While the editor has a point of view on the issues, to the greatest extent possible he has tried to not let that influence document selection, e.g., by selectively withholding or including documents that may buttress one point of view or the other. The task of compilation involved consultation of primary sources at the National Archives, mainly in Manhattan Project files held in the records of the Army Corps of Engineers, Record Group 77, but also in the archival records of the National Security Agency. Private collections were also important, such as the Henry L. Stimson Papers held at Yale University (although available on microfilm, for example, at the Library of Congress) and the papers of W. Averell Harriman at the Library of Congress. To a great extent the documents selected for this compilation have been declassified for years, even decades; the most recent declassifications were in the 1990s.

The U.S. documents cited here will be familiar to many knowledgeable readers on the Hiroshima-Nagasaki controversy and the history of the Manhattan Project. To provide a fuller picture of the transition from U.S.-Japanese antagonism to reconciliation, the editor has done what could be done within time and resource constraints to present information on the activities and points of view of Japanese policymakers and diplomats. This includes a number of formerly top secret summaries of intercepted Japanese diplomatic communications, which enable interested readers to form their own judgments about the direction of Japanese diplomacy in the weeks before the atomic bombings. Moreover, to shed light on the considerations that induced Japan's surrender, this briefing book includes new translations of Japanese primary sources on crucial events, including accounts of the conferences on August 9 and 14, where Emperor Hirohito made decisions to accept Allied terms of surrender.
[Editor's Note: Originally prepared in July 2005 this posting has been updated, with new documents, changes in organization, and other editorial changes. As noted, some documents relating to the origins of the Manhattan Project have been included in addition to entries from the Robert P. Meiklejohn diaries and translations of a few Soviet documents, among other items. Moreover, recent significant contributions to the scholarly literature have been taken into account.]

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The Atomic Bomb and the End of World War II

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To mark the 75th anniversary of the atomic bombings of Hiroshima and Nagasaki in August 1945, the National Security Archive is updating and reposting one of its most popular e-books of the past 25 years.