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Atomic Bomb: Nuclear Bomb, Hiroshima & Nagasaki - HISTORY

ic Bomb: Nuclear Bomb, Hiroshima & Nagasaki - HISTORYShowsThis Day In HistoryScheduleTopicsStoriesHistory ClassicsLive TVYour ProfileYour ProfileHistoryFind History on Facebook (Opens in a new window)Find History on Twitter (Opens in a new window)Find History on YouTube (Opens in a new window)Find History on Instagram (Opens in a new window)Find History on TikTok (Opens in a new window)Email UpdatesLive TVHistory ClassicsShowsThis Day In HistoryScheduleTopicsStoriesVideosHistory PodcastsHistory VaultShopHomeTopicsWorld War IIAtomic Bomb HistoryAtomic Bomb HistoryBy: History.com EditorsUpdated: November 9, 2022 | Original: September 6, 2017copy page linkPrint PageThermonuclear explosion at Bikini Atoll, March 1954. (Ann Ronan Pictures/Print Collector/Getty Images)Table of ContentsNuclear Bombs and Hydrogen BombsManhattan ProjectWho Invented the Atomic Bomb?Hiroshima And Nagasaki Bombings The Cold War Cuban Missile Crisis Three Mile Island Nuclear Non-Proliferation Treaty (NPT) Illegal Nuclear Weapon StatesNorth KoreaSourcesThe atomic bomb and nuclear bombs are powerful weapons that use nuclear reactions as their source of explosive energy. Scientists first developed nuclear weapons technology during World War II. Atomic bombs have been used only twice in war—both times by the United States against Japan at the end of World War II, in Hiroshima and Nagasaki. A period of nuclear proliferation followed that war, and during the Cold War, the United States and the Soviet Union vied for supremacy in a global nuclear arms race.Nuclear Bombs and Hydrogen BombsA discovery by nuclear physicists in a laboratory in Berlin, Germany, in 1938 made the first atomic bomb possible, after Otto Hahn, Lise Meitner and Fritz Strassman discovered nuclear fission.In nuclear fission, the nucleus of an atom of radioactive material splits into two or more smaller nuclei, which causes a sudden, powerful release of energy. The discovery of nuclear fission opened up the possibility of nuclear technologies, including weapons.Atomic bombs get their energy from fission reactions. Thermonuclear weapons, or hydrogen bombs, rely on a combination of nuclear fission and nuclear fusion. Nuclear fusion is another type of reaction in which two lighter atoms combine to release energy.History Shorts: How the Atomic Bomb Was Used in WWIIManhattan ProjectOn December 28, 1942, President Franklin D. Roosevelt authorized the formation of the Manhattan Project to bring together various scientists and military officials working on nuclear research.The Manhattan Project was the code name for the American-led effort to develop a functional atomic bomb during World War II. The project was started in response to fears that German scientists had been working on a weapon using nuclear technology since the 1930s.Who Invented the Atomic Bomb?Much of the work in the Manhattan Project was performed in Los Alamos, New Mexico, under the direction of theoretical physicist J. Robert Oppenheimer, the “father of the atomic bomb.” On July 16, 1945, in a remote desert location near Alamogordo, New Mexico, the first atomic bomb was successfully detonated—the Trinity Test. It created an enormous mushroom cloud some 40,000 feet high and ushered in the Atomic Age.Hiroshima And Nagasaki Bombings An atomic bomb, codenamed "Little Boy," was dropped over Hiroshima Japan on August 6, 1945. The bomb, which detonated with an energy of around 15 kilotons of TNT, was the first nuclear weapon deployed in wartime. The crew of the Boeing B-29 bomber, Enola Gay, which made the flight over Hiroshima to drop the first atomic bomb. Left to right kneeling; Staff Sergeant George R. Caron; Sergeant Joe Stiborik; Staff Sergeant Wyatt E. Duzenbury; Private first class Richard H. Nelson; Sergeant Robert H. Shurard. Left to right standing; Major Thomas W. Ferebee, Group Bombardier; Major Theodore Van Kirk, Navigator; Colonel Paul W. Tibbetts, 509th Group Commander and Pilot; Captain Robert A. Lewis, Airplane Commander. A view of the atomic bomb as it is hoisted into the bay of the Enola Gay on the North Field of Tinian airbase, North Marianas Islands, early August, 1945. Hiroshima in ruins after the dropping of the atomic bomb on August 6, 1945. The circle indicates the target of the bomb. The bomb directly killed an estimated 80,000 people. By the end of the year, injury and radiation brought the total number of deaths to between 90,000 and 166,000. The plutonium bomb, nicknamed "Fat Man," is shown in transport. It would be the second nuclear bomb dropped by U.S. forces in World War II.An Allied correspondent stands in rubble on September 7, 1945, looking to the ruins of a cinema after the atomic bomb attack on Hiroshima.Children in Hiroshima, Japan are shown wearing masks to combat the odor of death after the city was destroyed two months earlier.Survivors hospitalized in Hiroshima show their bodies covered with keloids caused by the atomic bomb.1 / 8: MPI/Getty ImagesScientists at Los Alamos had developed two distinct types of atomic bombs by 1945—a uranium-based design called “the Little Boy” and a plutonium-based weapon called “the Fat Man.” (Uranium and plutonium are both radioactive elements.)While the war in Europe had ended in April, fighting in the Pacific continued between Japanese forces and U.S. troops. In late July, President Harry Truman called for Japan’s surrender with the Potsdam Declaration. The declaration promised “prompt and utter destruction” if Japan did not surrender.On August 6, 1945, the United States dropped its first atomic bomb from a B-29 bomber plane called the Enola Gay over the city of Hiroshima, Japan. The “Little Boy” exploded with about 13 kilotons of force, leveling five square miles of the city and killing 80,000 people instantly. Tens of thousands more would later die from radiation exposure.When the Japanese did not immediately surrender, the United States dropped a second atomic bomb three days later on the city of Nagasaki. The “Fat Man” killed an estimated 40,000 people on impact.Nagasaki had not been the primary target for the second bomb. American bombers initially had targeted the city of Kokura, where Japan had one of its largest munitions plants, but smoke from firebombing raids obscured the sky over Kokura. American planes then turned toward their secondary target, Nagasaki.Citing the devastating power of “a new and most cruel bomb,” Japanese Emperor Hirohito announced his country’s surrender on August 15—a day that became known as ‘V-J Day’—ending World War II.The Cold War On August 29, 1949, the Soviet Union detonated its first nuclear device, signaling a new and terrifying phase in the Cold War. By the early 1950s, school children began practicing "Duck and Cover" air-raid drills in schools, as in this 1955 photo. Read more: How 'Duck-and-Cover' Drills Channeled America's Cold War AnxietyThe drills were part of President Harry S. Truman’s Federal Civil Defense Administration program and aimed to educate the public about what ordinary people could do to protect themselves.In 1951, the FCDA hired Archer Productions, a New York City ad agency, to create a film to educate schoolchildren about how to protect themselves in the case of atomic attack. The resulting film, Duck and Cover, was filmed at a school in Astoria, Queens, and alternated animation with images of students and adults practicing the recommended safety techniques.Two sisters sit together in their home after an atomic war drill with their family. They're holding up identification tags they wear around their necks in the March 1954 photo. A family during an atomic war drill. The drills were easy to mock—how could ducking and covering really protect you from a nuclear bomb? However, some historians argue the drills could have offered some protection if a blast (of a smaller scale) occurred a distance away.In 1961, the Soviets exploded a 58-megaton bomb dubbed “Tsar Bomba,” which had a force equivalent to more than 50 million tons of TNT—more than all the explosives used in World War II. In response, the focus of U.S. civil defense had moved on to the construction of fallout shelters. Here, a mother and her children make a practice run for their $5,000 steel backyard fallout shelter in Sacramento, California, on Oct. 5, 1961This fiberglass-reinforced plastic portable shelter was unveiled on Bolling Field in Washington, D.C. on June 13, 1950. Designed for both military personnel and equipment, it was made up of 12 separated sections, each interchangeable with any other. According to its manufacturer, the shelter could be erected or dismantled by three men in 30 to 45 minutes and could comfortably accommodate 12 men barracks-style, or 20 in field conditions. In this Sept. 12, 1958 file picture, Beverly Wysocki, top, and Marie Graskamp, right, Two women emerge from a family-type bomb shelter on display in Milwaukee, Wisconsin on September 12, 1958. This is an interior view of 4,500-lb. steel underground radiation fallout shelter where a couple with three children relax amidst bunk beds and shelves of provisions. Their backyard shelter also included a radio and crates of canned food and water. During the Cold War arms race, Americans were bombarded with contradictory images and messages that frightened even as they tried to reassure. 1 / 9: American Stock/Getty ImagesThe United States was the only country with nuclear weaponry in the years immediately following World War II. The Soviet Union initially lacked the knowledge and raw materials to build nuclear warheads.Within just a few years, however, the U.S.S.R. had obtained—through a network of spies engaging in international espionage—blueprints of a fission-style bomb and discovered regional sources of uranium in Eastern Europe. On August 29, 1949, the Soviets tested their first nuclear bomb.The United States responded by launching a program in 1950 to develop more advanced thermonuclear weapons. The Cold War arms race had begun, and nuclear testing and research became high-profile goals for several countries, especially the United States and the Soviet Union.Cuban Missile Crisis Over the next few decades, each world superpower would stockpile tens of thousands of nuclear warheads. Other countries, including Great Britain, France, and China, developed nuclear weapons during this time, too.To many observers, the world appeared on the brink of nuclear war in October of 1962. The Soviet Union had installed nuclear-armed missiles on Cuba, just 90 miles from U.S. shores. This resulted in a 13-day military and political standoff known as the Cuban Missile Crisis.President John F. Kennedy enacted a naval blockade around Cuba and made it clear the United States was prepared to use military force if necessary to neutralize the perceived threat.Disaster was avoided when the United States agreed to an offer made by Soviet leader Nikita Khrushchev to remove the Cuban missiles in exchange for the United States promising not to invade Cuba.Three Mile Island Many Americans became concerned about the health and environmental effects of nuclear fallout—the radiation left in the environment after a nuclear blast—in the wake of World War II and after extensive nuclear weapons testing in the Pacific during the 1940s and 1950s.The antinuclear movement emerged as a social movement in 1961 at the height of the Cold War. During Women Strike for Peace demonstrations on November 1, 1961 co-organized by activist Bella Abzug, roughly 50,000 women marched in 60 cities in the United States to demonstrate against nuclear weapons.The antinuclear movement captured national attention again in the 1970s and 1980s with high profile protests against nuclear reactors after the Three Mile Island accident—a nuclear meltdown at a Pennsylvania power plant in 1979.In 1982, a million people marched in New York City protesting nuclear weapons and urging an end to the Cold War nuclear arms race. It was one of the largest political protests in United States history.Nuclear Non-Proliferation Treaty (NPT) The United States and Soviet Union took the lead in negotiating an international agreement to halt the further spread of nuclear weapons in 1968.The Treaty on the Non-Proliferation of Nuclear Weapons (also called the Non-Proliferation Treaty or NPT) went into effect in 1970. It separated the world’s countries into two groups—nuclear weapons states and non-nuclear weapons states.Nuclear weapons states included the five countries that were known to possess nuclear weapons at the time—the United States, the U.S.S.R., Great Britain, France and China.According to the treaty, nuclear weapons states agreed not to use nuclear weapons or help non-nuclear states acquire nuclear weapons. They also agreed to gradually reduce their stockpiles of nuclear weapons with the eventual goal of total disarmament. Non-nuclear weapons states agreed not to acquire or develop nuclear weapons.When the Soviet Union collapsed in the early 1990s, there were still thousands of nuclear weapons scattered across Eastern Europe and Central Asia. Many of the weapons were located in Belarus, Kazakhstan and Ukraine. These weapons were deactivated and returned to Russia.The Interstate System...and Atomic Bombs?Illegal Nuclear Weapon StatesSome countries wanted the option of developing their own nuclear weapons arsenal and never signed the NPT. India was the first country outside of the NPT to test a nuclear weapon in 1974.Other non-signatories to the NTP include: Pakistan, Israel and South Sudan. Pakistan has a known nuclear weapons program. Israel is widely believed to possess nuclear weapons, though has never officially confirmed or denied the existence of a nuclear weapons program. South Sudan is not known or believed to possess nuclear weapons.North KoreaNorth Korea initially signed the NPT treaty, but announced its withdrawal from the agreement in 2003. Since 2006, North Korea has openly tested nuclear weapons, drawing sanctions from various nations and international bodies.North Korea tested two long-range intercontinental ballistic missiles in 2017—one reportedly capable of reaching the United States mainland. In September 2017, North Korea claimed it had tested a hydrogen bomb that could fit on top an intercontinental ballistic missile.Iran, while a signatory of the NPT, has said it has the capability to initiate production of nuclear weapons at short notice.SourcesPioneering Nuclear Science: The Discovery of Nuclear Fission. International Atomic Energy Agency. The Development and Proliferation of Nuclear Weapons. NobelPrize.org. Here are the facts about North Korea’s nuclear test. NPR.By: History.com EditorsHISTORY.com works with a wide range of writers and editors to create accurate and informative content. All articles are regularly reviewed and updated by the HISTORY.com team. Articles with the “HISTORY.com Editors” byline have been written or edited by the HISTORY.com editors, including Amanda Onion, Missy Sullivan, Matt Mullen and Christian Zapata.

Citation InformationArticle TitleAtomic Bomb HistoryAuthorHistory.com EditorsWebsite NameHISTORYURLhttps://www.history.com/topics/world-war-ii/atomic-bomb-historyDate AccessedMarch 9, 2024PublisherA&E Television NetworksLast UpdatedNovember 9, 2022Original Published DateSeptember 6, 2017Fact CheckWe strive for accuracy and fairness. But if you see something that doesn't look right, click here to contact us! HISTORY reviews and updates its content regularly to ensure it is complete and accurate.Print PageSign up for Inside HistoryGet HISTORY’s most fascinating stories delivered to your inbox three times a week.Sign UpBy submitting your information, you agree to receive emails from HISTORY and A+E Networks. You can opt out at any time. You must be 16 years or older and a resident of the United States.More details: Privacy Notice | Terms of Use | Contact UsA+E NetworksOur Family of BrandsHistory EducationHistory VaultMobile/AppsNewsShopShare Your OpinionFollow Historydepm+BiographyCrime and InvestigationHistory en EspanolLRWMilitary HistoryAd ChoicesAdvertise With UsAccessibility SupportCopyright PolicyCorporate InformationEmployment OpportunitiesFAQ/Contact UsPrivacy NoticeCookie NoticeTerms Of UseTV Parental GuidelinesContact UsCopyright PolicyPrivacy PolicyTerms of UseAd ChoicesAccessibility Support© 2024, A&E Television Networks, LLC. All Rights Reserv

Atomic bombings of Hiroshima and Nagasaki | Date, Significance, Timeline, Deaths, & Aftermath | Britannica

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atomic bombings of Hiroshima and Nagasaki

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atomic bombings of Hiroshima and Nagasaki

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Introduction & Top QuestionsEarly atomic researchThe Manhattan ProjectThe American atomic program takes shapeFrom Stagg Field to Los AlamosThe Trinity testThe bombing of HiroshimaThe bombing of NagasakiThe Japanese surrenderCasualties, damage, and the legacy of Hiroshima and Nagasaki

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What were the atomic bombings of Hiroshima and Nagasaki? The atomic bombings of Hiroshima and Nagasaki were American bombing raids on the Japanese cities of Hiroshima and Nagasaki during World War II, which marked the first use of atomic weapons in war. Little Boy, the bomb dropped on Hiroshima, was a gun-assembly fission bomb using uranium, whereas Fat Man, the bomb dropped on Nagasaki, was an implosion fission bomb utilizing plutonium. When were the atomic bombs dropped on Hiroshima and Nagasaki? The first atomic bomb, named Little Boy, was dropped on Hiroshima from the Enola Gay, a B-29 bomber, at 8:15 AM on August 6, 1945. The second bomb, named Fat Man, was dropped on Nagasaki from the Bockscar, also a B-29 bomber, at 11:02 AM on August 9, 1945. Who was involved in the atomic bombings of Hiroshima and Nagasaki? American physicist J. Robert Oppenheimer headed the Manhattan Project to develop atomic bombs for the United States, and Edward Teller was among the first scientists recruited for the project. Leo Szilard and Enrico Fermi built the first nuclear reactor. Ernest Orlando Lawrence was program chief in charge of the development of the electromagnetic process of separating uranium-235. The person who oversaw the project, however, was not a scientist. He was U.S. Army Brigadier General Leslie R. Groves. In all, more than one hundred thousand people were employed for the Manhattan Project. The bombings themselves were carried out by the pilot of the Enola Gay Colonel Paul Warfield Tibbets, Jr., and pilot of the Bockscar Major Charles W. Sweeney and their respective crews. Why did the atomic bombings of Hiroshima and Nagasaki happen? A number of factors contributed to the United States’ decision to drop atomic bombs on Japan. One reason was Japan’s unwillingness to surrender unconditionally. Japan wanted to keep their emperor and conduct their own war trials and did not want to be occupied by U.S. forces. However, the United States wanted unconditional surrender, which thus meant the continuation of the war. Japan refused to surrender after multiple firebombing campaigns such as the Bombing of Tokyo on March 9–10, 1945. The Bombing of Tokyo alone claimed tens of thousands of lives and is often cited as one of the most destructive acts of war in history. Although the precise death toll is unknown, conservative estimates suggest that the firestorm caused by incendiary bombs killed at least 80,000 people, likely more than 100,000, in a single night; some one million people were left homeless. It looked increasingly likely that the United States would have to commit itself to a land invasion, which could have claimed many American lives. Instead, the atomic bomb served as a tool to bring the war in the Pacific to a close sooner.Another reason why the United States dropped the atomic bombs—and, specifically, the second one on Nagasaki—has to do with the Soviet Union. On August 8, 1945, two days after the Hiroshima bombing, as agreed to by Joseph Stalin during the Tehrān and Yalta conferences in 1943 and 1945, respectively, the Soviet Union declared war on Japan. It is possible that U.S. President Harry Truman ordered the atomic bomb to be dropped on Nagasaki not only to further force Japan to surrender but also to keep the Soviets out of Japan by displaying American military power. Distrust and a sense of rivalry had been built up between the two superpowers that ultimately culminated in the Cold War. What were the results of the atomic bombings of Hiroshima and Nagasaki? The atomic bombings of Hiroshima and Nagasaki produced effects in Japan and around the world that changed the course of history. Tens of thousands of people were killed in the initial explosions (an estimated 70,000 in Hiroshima and 40,000 in Nagasaki), and many more later succumbed to burns, injuries, and radiation poisoning. On August 10, 1945, one day after the bombing of Nagasaki, the Japanese government issued a statement agreeing to accept the Allied surrender terms that had been dictated in the Potsdam Declaration. The United States gained wide-reaching influence in Japan during its occupation and as a result of its installation of the Supreme Commander for the Allied Powers, a title held by the American general Douglas MacArthur. The U.S. occupation of Japan had long and lasting effects on daily life in Japan as well as on Japan’s economy, military, and government.The atomic bombings of Hiroshima and Nagasaki also caused global effects such as the Cold War and the proliferation of nuclear weapons around the world. The Cold War was a rivalry that saw the world’s two remaining superpowers after World War II—the United States and the Soviet Union, as well as their respective allies—fight for political, economic, and nuclear superiority. Today, more countries possess nuclear weapons, but such weapons have not been used in warfare since the bombings of Hiroshima and Nagasaki. Discover more about the first atomic bombs, tested and used during World War IIThe first atomic bomb was detonated on July 16, 1945, in New Mexico as part of the U.S. government program called the Manhattan Project. The United States then used atomic bombs on Hiroshima and Nagasaki in Japan on August 6 and 9, respectively, killing about 210,000 people. This infographic describes these early bombs, how they worked, and how they were used.(more)atomic bombings of Hiroshima and Nagasaki, during World War II, American bombing raids on the Japanese cities of Hiroshima (August 6, 1945) and Nagasaki (August 9, 1945) that marked the first use of atomic weapons in war. Tens of thousands were killed in the initial explosions and many more would later succumb to radiation poisoning. On August 10, one day after the bombing of Nagasaki, the Japanese government issued a statement agreeing to accept the Allied surrender terms that had been dictated in the Potsdam Declaration. Early atomic research nuclear fissionThe impact of a slow (low-energy) neutron splitting the nucleus of the uranium isotope U-235 into two new nuclei. These can be nuclei of any of 30 or more elements ranging in atomic number from 30 to 64. Krypton and barium are examples. Energy and neutrons (2 or 3 for an average of about 2.5) are also produced.(more)Otto HahnThe turning point in the quest for atomic energy came in January 1939, eight months before the start of World War II. German scientists Otto Hahn and Fritz Strassmann, following a clue provided by Irène Joliot-Curie and Pavle Savić in France (1938), proved definitely that the bombardment of uranium with neutrons produced radioisotopes of barium, lanthanum, and other elements from the middle of the periodic table. Lise Meitner and Otto HahnPhysicist Lise Meitner and chemist Otto Hahn at the Kaiser Wilhelm Institute of Chemistry, Berlin-Dahlem, Germany, 1913.(more)Neils BohrNiels Bohr.(more)Observe an animation of sequential events in the fission of a uranium nucleus by a neutronSequence of events in the fission of a uranium nucleus by a neutron.(more)See all videos for this articleThe significance of this discovery was communicated by Lise Meitner and Otto Frisch, two Jewish scientists who had fled Germany, to Niels Bohr in Copenhagen. Bohr had been preparing to journey to the United States, and he arrived in New York on January 16, 1939. He discussed the matter with Albert Einstein, John Archibald Wheeler, and others before announcing to the world on January 26 the discovery of a process that Meitner and Frisch had termed fission. Enrico Fermi proposed to Bohr that neutrons might be released during the fission process, thus raising the possibility of a sustained nuclear chain reaction. These revolutionary suggestions triggered a flurry of activity in the world of physics. Subsequent studies by Bohr and Wheeler indicated that fission did not occur in uranium-238, the isotope of uranium most commonly found in nature, but that fission could take place in uranium-235. Gradually many of the riddles surrounding fission were resolved, and by June 1940 the basic facts concerning the release of atomic energy were known throughout the scientific world. The Manhattan Project The American atomic program takes shape The true story of Oppenheimer and the atomic bombDr. J. Robert Oppenheimer became involved in nuclear research in 1941. His biopic, Oppenheimer, was released in 2023.(more)See all videos for this articleWhile engaged in one war in Europe and another in the Pacific, the United States would launch the largest scientific effort undertaken to that time. It would involve 37 installations throughout the country, more than a dozen university laboratories, and 100,000 people, including the Nobel Prize-winning physicists Arthur Holly Compton, Enrico Fermi, Richard Feynman, Ernest Lawrence, and Harold Urey.

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The first contact between the scientific community and the U.S. government regarding atomic research was made by George B. Pegram of Columbia University. Pegram arranged a conference between Fermi and officers of the U.S. Navy in March 1939. In July Leo Szilard and Eugene Wigner conferred with Einstein, and the three later went to New York to meet with National Recovery Administration economist Alexander Sachs. Supported by a letter from Einstein, Sachs approached Pres. Franklin D. Roosevelt and explained the significance of nuclear fission to him. Roosevelt formed the Advisory Committee on Uranium, appointing Lyman Briggs, director of the National Bureau of Standards, to serve as its chair. In February 1940 a fund of $6,000 was made available to begin research; by the time of its completion, the project’s budget would exceed $2 billion. U.S. officials were now well aware of Adolf Hitler’s atomic ambitions. In his letter to Roosevelt, Einstein explicitly called attention to uranium reserves in Czechoslovakia that had fallen under the control of the Third Reich in March 1939. The British had also begun studying fission, and Urey and Pegram visited the United Kingdom to see what was being done there. By August 1943 a combined policy committee had been established with the United Kingdom and Canada. Later that year a number of scientists of those countries moved to the United States to join the project that by then was well underway.

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James B. ConantJames B. Conant, 1933.(more)Vannevar Bush with Differential AnalyzerVannevar Bush with his Differential Analyzer, c. 1935.(more)On December 6, 1941, one day before the Japanese attack on Pearl Harbor, the project was placed under the direction of Vannevar Bush and the Office of Scientific Research and Development (OSRD). Bush’s staff included Harvard University Pres. James B. Conant, Pegram, Urey, and Lawrence, among others. Alongside this scientific body was created the “Top Policy Group,” consisting of Bush, Conant, Roosevelt, U.S. Vice Pres. Henry Wallace, U.S. Secretary of War Henry Stimson, and U.S. Army Chief of Staff George C. Marshall. Because there was no way of knowing in advance what technique would succeed in creating a functional bomb, it was decided to work simultaneously on several methods of isolating uranium-235 while also researching reactor development. The goal was twofold: to learn more about the chain reaction for bomb design and to develop a method of producing a new element, plutonium, which was expected to be fissile and could be isolated from uranium chemically. Lawrence and his team developed an electromagnetic separation process at the University of California, Berkeley, while Urey’s group at Columbia University experimented with the conversion of uranium into a gaseous compound that was then permitted to diffuse through porous barriers. Both of these processes, particularly the diffusion method, required large complex facilities and huge amounts of electric power to produce even small amounts of separated uranium-235. It soon became clear that an enormous physical infrastructure would have to be built to support the project. From Stagg Field to Los Alamos Leslie GrovesOn June 18, 1942, the War Department assigned management of construction work related to the project to the U.S. Army Corps of Engineers’ Manhattan District (much early atomic research—most notably Urey’s group—was based at Manhattan’s Columbia University). On September 17, 1942, Brig. Gen. Leslie R. Groves was placed in charge of all Army activities relating to the project. “Manhattan Project” became the code name applied to this body of atomic research that would extend across the country. first self-sustaining nuclear chain reactionScientists observing the world's first self-sustaining nuclear chain reaction, in the Chicago Pile No. 1, December 2, 1942. Photograph of an original painting by Gary Sheehan, 1957.(more)The first experimental reactor—a graphite cube about 8 feet (2.4 metres) on edge and containing about seven tons of uranium oxide—had been set up at Columbia University in July 1941. By the end of that year, reactor work had been transferred to the University of Chicago, where Arthur Holly Compton and his cryptically named “Metallurgical Laboratory” were considering related problems. On December 2, 1942, the first self-sustaining nuclear chain reaction was carried out under Fermi’s supervision in Chicago Pile No. 1, a reactor that Fermi had constructed in a squash court under the bleachers of Stagg Field, the university’s football stadium. It had now been proven that the controlled release of atomic energy was feasible for the production of power and the manufacture of plutonium. Oak Ridge National LaboratoryWorkers using a long rod to push uranium slugs into the concrete loading face of the graphite reactor at Oak Ridge National Laboratory, Oak Ridge, Tennessee.(more)In February 1943 construction began on a pilot uranium enrichment plant located on the Clinch River in the Tennessee Valley, about 15 miles (about 24 km) west of Knoxville, Tennessee. The Clinton Engineer Works (later known as Oak Ridge) occupied a 70-square-mile (180-square-km) tract of land and came to employ roughly 5,000 technicians and maintenance personnel. For the project’s full-sized reactors, however, a more isolated site would be necessary. Groves had expressed concern about the pilot reactor’s proximity to Knoxville, and the larger reactors would have significantly greater power needs than could be accommodated in the Tennessee Valley. Columbia River basinIn January 1943 Groves had selected a 580-square-mile (1,500-square-km) tract in south-central Washington for the project’s plutonium production facilities. The location was desirable for its relative isolation and for the availability, in large quantities, of cooling water from the Columbia River and electric power from the Grand Coulee Dam and Bonneville Dam hydroelectric installations. The creation of what came to be known as the Hanford Engineer Works required a significant displacement of the local population. Residents of the towns of Hanford, Richland, and White Bluffs were given just 90 days to vacate their homes, and the Wanapum Native American people were forced to relocate to Priest Rapids, losing access to their traditional fishing grounds on the Columbia. At its peak in the summer of 1944, the huge complex at Hanford employed more than 50,000 people. J. Robert OppenheimerJ. Robert Oppenheimer, c. 1944.(more)For the final stages of the project, it was necessary to find a location that was even more remote than Hanford for the purposes of both security and safety. A site was chosen by the Manhattan Project’s scientific director, J. Robert Oppenheimer, on an isolated mesa at Los Alamos, New Mexico, 34 miles (55 km) north of Santa Fe. Beginning in April 1943, scientists and engineers began arriving at the Los Alamos Laboratory, as it was then called. Under Oppenheimer’s direction, this team was tasked with developing methods of reducing the fissionable products of the Clinton and Hanford production plants to pure metal and fabricating that metal into the components of a deliverable weapon. The weapon had to be small enough that it could be dropped from a plane and simple enough that it could be fused to detonate at the proper moment in the air above the target. Most of these issues had to be addressed before any significant stores of fissionable material had been produced, so that the first adequate amounts could be used in a functional bomb. At its peak in 1945 more than 5,000 scientists, engineers, technicians, and their families lived at the Los Alamos site. The Trinity test Pacific WarThe Allied approach to the Japanese home islands during the final phase of the Pacific War, 1945.(more)Roosevelt died on April 12, 1945, and within 24 hours Pres. Harry S. Truman had been briefed about the atomic bomb program by Stimson. Germany surrendered in May 1945, thus ending the war in Europe, but combat raged on in the Pacific. Sanguinary battles at Iwo Jima (February–March 1945) and Okinawa (April–June 1945) offered a preview of what an invasion of the Japanese home islands might look like, and there remained a strong impetus to see the Manhattan Project through to its conclusion. By the summer of 1945, the production plants had delivered a sufficient amount of fissionable material to produce a nuclear explosion, and bomb development had advanced to a point that an actual field test of a nuclear weapon could be conducted. Such a test would obviously be no simple affair. A vast array of complex equipment had to be assembled so that the success or failure of the test could be analyzed. fission bombThe three most common fission bomb designs, which vary considerably in material and arrangement.(more)The bomb development teams at Los Alamos had settled on two possible designs. One, fueled by uranium-235, would utilize a “gun assembly” that used high explosives to shoot two subcritical slugs of fissionable material together in a hollow tube. The violent collision of the two slugs would cause the uranium-235 to reach critical mass, thus triggering a chain reaction and explosion. Engineers were confident that this comparatively simple design would work, but a sufficient quantity of uranium-235 would not be available until about August 1, 1945. The Hanford site would be able to deliver enough plutonium-239 for testing by early July, but Los Alamos scientists had determined that the gun assembly model would not be compatible with plutonium as a fuel source. An alternative design had been proposed, one that would use concentric layers of high explosives to implode the fissionable material under enormous pressures into a denser mass that would immediately achieve criticality. It was believed that this “implosion” design would be the most efficient way to weaponize the meagre amount of plutonium that had been produced thus far. J. Robert Oppenheimer and Leslie R. GrovesJ. Robert Oppenheimer (left) and Gen. Leslie R. Groves examining the remains of a steel tower at the Trinity test site in Alamogordo, New Mexico, September 1945.(more)For the test, Oppenheimer selected a location on the Alamogordo Bombing Range (now White Sands Missile Range), 120 miles (193 km) south of Albuquerque, New Mexico. He called the site “Trinity” in reference to one of John Donne’s Holy Sonnets. The first atomic bomb—a plutonium implosion device called “Gadget”—was raised to the top of a 100-foot (30-metre) steel tower that was designated “Zero.” The area at the base of the tower was marked as “Ground Zero,” a term that would pass into common parlance to describe the centre of an (often catastrophic) event. Military officials and scientists occupied observation posts at distances ranging from 10,000 to 17,000 yards (9 to 15.5 km). They had been instructed to lie down with their feet toward the tower and to protect their eyes from the blinding flash of the explosion. atomic bombThe first atomic bomb test, near Alamogordo, New Mexico, July 16, 1945.(more)trinitite; Manhattan ProjectTrinitite, also known as atomsite or Alamogordo glass, produced by the intense heat released from the Trinity nuclear bomb test on July 16, 1945, near Alamogordo, New Mexico.(more)On the morning of the test, the skies were dark and it was raining, with occasional lightning. “Gadget” was detonated at 5:29:45 am on July 16, 1945. The explosion caused a flash that illuminated the mountain peaks 10 miles (16 km) away. Soon there followed a tremendous sustained roar accompanied by a tornado-like burst of wind. Where the tower had stood, there was a great surging ball of fire, followed by a mushroom cloud that rose some 40,000 feet (12,200 metres) into the sky. The heat of the explosion had completely vaporized the tower; in its place was a saucer-shaped crater about a half mile (800 metres) in diameter and 25 feet (almost 8 metres) deep. The floor of the crater was fused into a glassy jade-coloured mineral subsequently dubbed trinitite. The bomb had generated an explosive power equivalent to approximately 21,000 tons of trinitrotoluene (TNT). The blast was visible from a distance of 50 miles (80 km), and it shattered windows 125 miles (200 km) away. Residents of Gallup, New Mexico, more than 180 miles (290 km) from Ground Zero, reported feeling the ground shake. In an attempt to head off questions about the world-changing event that had occurred at Trinity, the army issued a brief statement to the press: “A remotely located ammunition magazine containing a considerable amount of high explosives and pyrotechnics exploded, but there was no loss of life or limb to anyone.” Winston Churchill, Harry Truman, and Joseph StalinBritish Prime Minister Winston Churchill, U.S. Pres. Harry S. Truman, and Soviet Premier Joseph Stalin meeting at Potsdam, Germany, in July 1945 to discuss the postwar order in Europe.(more)Northern Mariana IslandsNews of the successful test reached Truman, who was attending the final meeting of the “Big Three” Allied powers at Potsdam, Germany. Truman informed Soviet leader Joseph Stalin that the United States possessed “a new weapon of unusual destructive force.” On July 26 the Big Three issued an ultimatum, calling on Japan to surrender unconditionally or face “prompt and utter destruction.” When it became clear that no surrender was imminent, plans to use the bomb went into effect. Some within the Manhattan Project had argued for a demonstration explosion on an uninhabited site in the Pacific. This was considered but soon discarded, largely because of concerns that the demonstration bomb might not prompt sufficient reaction from the Japanese government. By this time, several dozen B-29 bombers had been modified to carry the weapons, and a staging base at Tinian, in the Mariana Islands, 1,500 miles (2,400 km) south of Japan, had been expanded into the largest airfield in the world. The bombing of Hiroshima Learn about the sinking of the USS IndianapolisThe USS Indianapolis delivered components of the atomic bombs dropped on Hiroshima and Nagasaki just days before it was sunk by a Japanese submarine on July 30, 1945. This infographic provides a timeline of the USS Indianapolis's role in World War II, a diagram showing the ship's dimensions, a map of the location of its sinking, and a graph summarizing American casualties that resulted from the sinking and delayed rescue. (more)USS IndianapolisUSS Indianapolis, July 1945.(more)The impact of the atomic bomb on HiroshimaHear Encyclopædia Britannica editor Michael Ray talk about the atomic bombing of Hiroshima by the United States on August 6, 1945.(more)See all videos for this articleOn July 16, just hours after the successful completion of the Trinity test, the heavy cruiser USS Indianapolis left port at San Francisco with the gun assembly mechanism, roughly half of the U.S. supply of uranium-235, and several Los Alamos technicians. The remainder of the U.S. uranium-235 stockpile was flown to Tinian on transport planes. Upon the arrival of the Indianapolis at Tinian on July 26, assembly began on the bomb, dubbed Little Boy. The Indianapolis departed Tinian after the delivery, but it was sunk en route to the Philippines by the Japanese submarine I-58 on July 30. Hundreds of crew members who survived the torpedo attack died in the water while awaiting a rescue. The components of a second bomb, a plutonium device nicknamed Fat Man, were transported to Tinian by air. By August 2, 1945, both bombs had arrived at Tinian, and U.S. commanders were waiting only for a break in the weather to order the execution of Special Bombing Mission 13—an atomic attack on the Japanese home islands. Hiroshima, JapanGroves had chaired the committee responsible for target selection, and by the end of May 1945 the list had been narrowed to Kokura, Hiroshima, Niigata, and Kyōto, all cities that had not yet been subjected to Gen. Curtis LeMay’s strategic bombing campaign. Kyōto, Japan’s ancient capital, was consistently placed at the top of the list, but Stimson appealed directly to Truman to remove it from consideration because of its cultural importance. Nagasaki was added in its place. Hiroshima became the primary target because of its military value—the city served as the headquarters of the Japanese Second Army—and because planners believed that the compactness of the urban centre would most vividly demonstrate the destructive power of the bomb. Paul W. Tibbets, Jr., and the Enola GayCol. Paul W. Tibbets, Jr., pilot of the Enola Gay, the plane that dropped an atomic bomb on Hiroshima, Japan, on August 6, 1945.(more)Enola GayThe B-29 Superfortress Enola Gay backed over a pit to be loaded with the first atomic bomb, which would be released on Hiroshima, Japan, on August 6, 1945.(more)The pilots, mechanics, and crews of the 509th Composite Group of the Twentieth Air Force had all trained with the specially modified B-29s that would serve as delivery vehicles for the bombs. Col. Paul W. Tibbets, Jr., the commander of the 509th, would pilot the B-29 that would drop the first bomb. His 11-man crew included Maj. Thomas Ferebee as bombardier and Manhattan Project ordnance expert Capt. William (“Deak”) Parsons as weaponeer. Tibbets personally selected plane number 82 for the mission, and, shortly before taking off at approximately 2:45 am on August 6, 1945, Tibbets asked a maintenance worker to paint his mother’s name—Enola Gay—on the nose of the aircraft. Two other B-29s accompanied the Enola Gay to serve as observation and camera planes. Once the Enola Gay was airborne, Parsons added the final components to Little Boy. This was done because a number of the modified B-29s had crashed on takeoff, and there was some concern that a crash would cause a fully assembled bomb to detonate, wiping out the installation at Tinian. Discover the facts about the atomic bombing of Hiroshima, Japan, during World War IIInfographic with relevant facts about the atomic bombing of Hiroshima, Japan.(more)Watch U.S. B-29 Superfortress Enola Gay decimate Hiroshima with a nuclear bomb in the Pacific WarThe B-29 Superfortress Enola Gay took off from the Mariana Islands on August 6, 1945, bound for Hiroshima, Japan, where, by dropping an atomic bomb, it heralded a new and terrible concept of warfare. From The Second World War: Allied Victory (1963), a documentary by Encyclopædia Britannica Educational Corporation.(more)See all videos for this articleThe skies were clear, and the Enola Gay encountered no opposition while approaching the target. At 7:15 am (Tinian time) Parsons armed the weapon, and the Enola Gay ascended to an attack altitude of 31,000 feet (9,450 metres). A trio of B-29s had flown ahead of the strike force to perform weather reconnaissance over the primary (Hiroshima) and secondary (Kokura and Nagasaki) targets. The pilot of the Hiroshima mission radioed Tibbets that there was little cloud cover and that he should proceed to the primary target. Just after 8:00 am local time (9:00 am Tinian time), the crew of the Enola Gay sighted Hiroshima. At around 8:12 am Tibbets relinquished control of the aircraft to Ferebee, who began his bombing run. Ferebee’s aim point was the Aioi Bridge, a distinctive T-shaped span over the Ōta River. Tibbets ordered his crew to don their protective goggles, and at 8:15 am the bomb was released. Tibbets immediately put the Enola Gay into a sharp turn that, he hoped, would carry it beyond the bomb’s blast radius. atomic bombing of HiroshimaAerial photograph of Hiroshima after it was struck by an atomic bomb on August 6, 1945.(more)aftermath of the atomic bombing of HiroshimaRuins of Hiroshima after the detonation of a U.S. atomic bomb on August 6, 1945. The Hiroshima Prefectural Industrial Promotion Hall (now known as the Atomic Bomb Dome) is visible in the distance.(more)It took roughly 45 seconds for Little Boy to descend to an altitude of 1,900 feet (580 metres), at which point it exploded in the sky directly above Shima Hospital. Within a fraction of a second of the detonation, the temperature at ground level exceeded 7,000 °C (12,600 °F) and a powerful blast wave scoured the landscape. Out of a population of 343,000 inhabitants, some 70,000 people were killed instantly, and by the end of the year the death toll had surpassed 100,000. Two-thirds of the city area was destroyed. “Nuclear shadows” were all that remained of people who had been subjected to the intense thermal radiation. A massive mushroom cloud rose to a height of more than 40,000 feet (more than 12 km). Although less than 2 percent of the uranium-235 contained in Little Boy had achieved fission, the bomb was horrifying in its destructive power. The explosive yield was the equivalent of 15,000 tons of TNT. Sgt. Bob Caron, the Enola Gay’s tail gunner and the only member of the crew to directly observe the blast, described the scene as a “peep into hell.” A series of shockwaves rocked the Enola Gay as it departed the area, and at a distance of nearly 400 miles (640 km) the mushroom cloud was still visible. Upon returning to Tinian, after a flight of just over 12 hours, Tibbets was awarded the Distinguished Service Cross. Harry S. TrumanHarry S. Truman, 1945.(more)Later that day, Truman addressed the people of the United States: Sixteen hours ago an American airplane dropped one bomb on Hiroshima, an important Japanese Army base. That bomb had more power than 20,000 tons of TNT. It had more than 2,000 times the blast power of the British “Grand Slam,” which is the largest bomb ever yet used in the history of warfare. The Japanese began the war from the air at Pearl Harbor. They have been repaid many fold. And the end is not yet. With this bomb we have now added a new and revolutionary increase in destruction to supplement the growing power of our armed forces. In their present form these bombs are now in production, and even more powerful forms are in development. It is an atomic bomb. It is a harnessing of the basic power of the universe. The force from which the sun draws its power has been loosed against those who brought war to the Far East. Truman further noted, “We have spent two billion dollars on the greatest scientific gamble in history—and won.” Poet and author James Agee, writing in Time, offered something of a counterpoint to Truman’s speech: The race had been won, the weapon had been used by those on whom civilization could best hope to depend; but the demonstration of power against living creatures instead of dead matter created a bottomless wound in the living conscience of the race. The rational mind had won the most Promethean of its conquests over nature, and had put into the hands of common man the fire and force of the sun itself. News of Hiroshima’s destruction was only slowly understood, and some Japanese officials argued that their own stalled atomic program had demonstrated how difficult it would be to create such a weapon. It was possible, they argued, that the bomb dropped on Hiroshima was the only one in the American arsenal. Other members of the Japanese government had been arguing for months in favour of a negotiated settlement, perhaps mediated by the Soviets. That window was abruptly closed on August 8, 1945, two days after the Hiroshima bombing, when the Soviet Union declared war against Japan.

Bombing of Hiroshima and Nagasaki - Causes, Impact & Lives Lost | HISTORY

ing of Hiroshima and Nagasaki - Causes, Impact & Lives Lost | HISTORYShowsThis Day In HistoryScheduleTopicsStoriesHistory ClassicsLive TVYour ProfileYour ProfileHistoryFind History on Facebook (Opens in a new window)Find History on Twitter (Opens in a new window)Find History on YouTube (Opens in a new window)Find History on Instagram (Opens in a new window)Find History on TikTok (Opens in a new window)Email UpdatesLive TVHistory ClassicsShowsThis Day In HistoryScheduleTopicsStoriesVideosHistory PodcastsHistory VaultShopHomeTopicsWorld War IIBombing of Hiroshima and NagasakiBombing of Hiroshima and NagasakiBy: History.com EditorsUpdated: April 18, 2023 | Original: November 18, 2009copy page linkPrint PagePrisma Bildagentur/Universal Images Group/Getty ImagesTable of ContentsThe Manhattan ProjectNo Surrender for the JapaneseWhy Did the U.S. Bomb Hiroshima and Nagasaki? Aftermath of the BombingOn August 6, 1945, during World War II (1939-45), an American B-29 bomber dropped the world’s first deployed atomic bomb over the Japanese city of Hiroshima. The explosion immediately killed an estimated 80,000 people; tens of thousands more would later die of radiation exposure. Three days later, a second B-29 dropped another A-bomb on Nagasaki, killing an estimated 40,000 people. Japan’s Emperor Hirohito announced his country’s unconditional surrender in World War II in a radio address on August 15, citing the devastating power of “a new and most cruel bomb.”The Manhattan ProjectEven before the outbreak of war in 1939, a group of American scientists—many of them refugees from fascist regimes in Europe—became concerned with nuclear weapons research being conducted in Nazi Germany. In 1940, the U.S. government began funding its own atomic weapons development program, which came under the joint responsibility of the Office of Scientific Research and Development and the War Department after the U.S. entry into World War II. The U.S. Army Corps of Engineers was tasked with spearheading the construction of the vast facilities necessary for the top-secret program, codenamed “The Manhattan Project” (for the engineering corps’ Manhattan district).Bombing of Hiroshima and NagasakiOver the next several years, the program’s scientists worked on producing the key materials for nuclear fission—uranium-235 and plutonium (Pu-239). They sent them to Los Alamos, New Mexico, where a team led by J. Robert Oppenheimer worked to turn these materials into a workable atomic bomb. Early on the morning of July 16, 1945, the Manhattan Project held its first successful test of an atomic device—a plutonium bomb—at the Trinity test site at Alamogordo, New Mexico.No Surrender for the JapaneseBy the time of the Trinity test, the Allied powers had already defeated Germany in Europe. Japan, however, vowed to fight to the bitter end in the Pacific, despite clear indications (as early as 1944) that they had little chance of winning. In fact, between mid-April 1945 (when President Harry Truman took office) and mid-July, Japanese forces inflicted Allied casualties totaling nearly half those suffered in three full years of war in the Pacific, proving that Japan had become even more deadly when faced with defeat. In late July, Japan’s militarist government rejected the Allied demand for surrender put forth in the Potsdam Declaration, which threatened the Japanese with “prompt and utter destruction” if they refused.General Douglas MacArthur and other top military commanders favored continuing the conventional bombing of Japan already in effect and following up with a massive invasion, codenamed “Operation Downfall.” They advised Truman that such an invasion would result in U.S. casualties of up to 1 million. In order to avoid such a high casualty rate, Truman decided–over the moral reservations of Secretary of War Henry Stimson, General Dwight Eisenhower and a number of the Manhattan Project scientists–to use the atomic bomb in the hopes of bringing the war to a quick end. Proponents of the A-bomb—such as James Byrnes, Truman’s secretary of state—believed that its devastating power would not only end the war, but also put the U.S. in a dominant position to determine the course of the postwar world.Why Did the U.S. Bomb Hiroshima and Nagasaki? Hiroshima, a manufacturing center of some 350,000 people located about 500 miles from Tokyo, was selected as the first target. After arriving at the U.S. base on the Pacific island of Tinian, the more than 9,000-pound uranium-235 bomb was loaded aboard a modified B-29 bomber christened Enola Gay (after the mother of its pilot, Colonel Paul Tibbets). The plane dropped the bomb—known as “Little Boy”—by parachute at 8:15 in the morning, and it exploded 2,000 feet above Hiroshima in a blast equal to 12-15,000 tons of TNT, destroying five square miles of the city.Hiroshima’s devastation failed to elicit immediate Japanese surrender, however, and on August 9 Major Charles Sweeney flew another B-29 bomber, Bockscar, from Tinian. Thick clouds over the primary target, the city of Kokura, drove Sweeney to a secondary target, Nagasaki, where the plutonium bomb “Fat Man” was dropped at 11:02 that morning. More powerful than the one used at Hiroshima, the bomb weighed nearly 10,000 pounds and was built to produce a 22-kiloton blast. The topography of Nagasaki, which was nestled in narrow valleys between mountains, reduced the bomb’s effect, limiting the destruction to 2.6 square miles.HISTORY Vault: Hiroshima - 75 Years LaterMarking the anniversary of the 1945 Hiroshima bombing, this special—told entirely from the first-person perspective of leaders, physicists, soldiers and survivors—provides a unique understanding of the most devastating experiment in human history.WATCH NOWAftermath of the BombingAt noon on August 15, 1945 (Japanese time), Emperor Hirohito announced his country’s surrender in a radio broadcast. The news spread quickly, and “Victory in Japan” or “V-J Day” celebrations broke out across the United States and other Allied nations. The formal surrender agreement was signed on September 2, aboard the U.S. battleship Missouri, anchored in Tokyo Bay.Because of the extent of the devastation and chaos—including the fact that much of the two cities' infrastructure was wiped out—exact death tolls from the bombing of Hiroshima and Nagasaki remain unknown. However, it's estimated roughly 70,000 to 135,000 people died in Hiroshima and 60,000 to 80,000 people died in Nagasaki, both from acute exposure to the blasts and from long-term side effects of radiation. A view of the atomic bomb, codenamed "Little Boy," as it is hoisted into the bay of the Enola Gay on the North Field of Tinian airbase, North Marianas Islands. The bomb was dropped over Hiroshima, Japan on August 6, 1945.The bomb detonated with an energy of around 15 kilotons of TNT and was the first nuclear weapon deployed in wartime. The crew of the Boeing B-29 bomber, Enola Gay, which made the flight over Hiroshima to drop the first atomic bomb. Left to right kneeling; Staff Sergeant George R. Caron; Sergeant Joe Stiborik; Staff Sergeant Wyatt E. Duzenbury; Private first class Richard H. Nelson; Sergeant Robert H. Shurard. Left to right standing; Major Thomas W. Ferebee, Group Bombardier; Major Theodore Van Kirk, Navigator; Colonel Paul W. Tibbetts, 509th Group Commander and Pilot; Captain Robert A. Lewis, Airplane Commander. An aerial view from a U.S. Air Force bomber of smoke rising from Hiroshima, shortly after 8:15 am. on August 6, 1945, after the atomic explosion. Hiroshima in ruins after the dropping of the atomic bomb, the circle indicating the target. The bomb directly killed an estimated 80,000 people and by the end of the year, injury and radiation brought the total number of deaths to between 90,000 and 166,000. The plutonium bomb, nicknamed "Fat Man," is shown in transport. It would be the second nuclear bomb dropped by U.S. forces in World War II.The second nuclear bomb was dropped on the city on August 9, 1945, in the last days of WWII shortly before the surrender of Japan. The attack destroyed about 30 percent of the city.Only the reinforced concrete buildings of the Nagasaki Medical College hospital remained standing after the August 9, 1945 bombing of the city. The hospital was located 800 meters from ground zero of the explosion.This area in the Nagasaki suburbs, four miles away from the city proper, was almost as badly damaged as the areas in the center of the city. Wreckage is piled high on either side of the roadway.A water soaked photo album, shards of pottery and a pair of scissors amid the devastation after the bombing on Nagasaki.An Allied correspondent stands in rubble on September 7, 1945, looking to the ruins of a cinema after the atomic bomb attack on Hiroshima.A homeless group of mostly children warm their hands over a fire on the outskirts of Hiroshima after the end of WWII. A victim of the atomic bomb blast over Hiroshima, in a makeshift hospital in a bank building, September 1945.Children in Hiroshima, Japan are shown wearing masks to combat the odor of death after the city was destroyed two months earlier.Hiroshima pictured eight months after the atomic bomb was dropped, still standing in ruins.Survivors hospitalized in Hiroshima show their bodies covered with keloids caused by the atomic bomb.1 / 16: PhotoQuest/Getty ImagesBy: History.com EditorsHISTORY.com works with a wide range of writers and editors to create accurate and informative content. All articles are regularly reviewed and updated by the HISTORY.com team. Articles with the “HISTORY.com Editors” byline have been written or edited by the HISTORY.com editors, including Amanda Onion, Missy Sullivan, Matt Mullen and Christian Zapata.

Citation InformationArticle TitleBombing of Hiroshima and NagasakiAuthorHistory.com EditorsWebsite NameHISTORYURLhttps://www.history.com/topics/world-war-ii/bombing-of-hiroshima-and-nagasakiDate AccessedMarch 9, 2024PublisherA&E Television NetworksLast UpdatedApril 18, 2023Original Published DateNovember 18, 2009Fact CheckWe strive for accuracy and fairness. But if you see something that doesn't look right, click here to contact us! HISTORY reviews and updates its content regularly to ensure it is complete and accurate.Print PageSign up for Inside HistoryGet HISTORY’s most fascinating stories delivered to your inbox three times a week.Sign UpBy submitting your information, you agree to receive emails from HISTORY and A+E Networks. You can opt out at any time. You must be 16 years or older and a resident of the United States.More details: Privacy Notice | Terms of Use | Contact UsA+E NetworksOur Family of BrandsHistory EducationHistory VaultMobile/AppsNewsShopShare Your OpinionFollow Historydepm+BiographyCrime and InvestigationHistory en EspanolLRWMilitary HistoryAd ChoicesAdvertise With UsAccessibility SupportCopyright PolicyCorporate InformationEmployment OpportunitiesFAQ/Contact UsPrivacy NoticeCookie NoticeTerms Of UseTV Parental GuidelinesContact UsCopyright PolicyPrivacy PolicyTerms of UseAd ChoicesAccessibility Support© 2024, A&E Television Networks, LLC. All Rights Reserv

The Most Fearsome Sight: The Atomic Bombing of Hiroshima | The National WWII Museum | New Orleans

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The Most Fearsome Sight: The Atomic…

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The Most Fearsome Sight: The Atomic Bombing of Hiroshima

On the morning of August 6, 1945, the American B-29 bomber Enola Gay dropped an atomic bomb on the Japanese city of Hiroshima.

August 6, 2020

Top Image: The devastated downtown of Hiroshima with the dome of the Hiroshima Prefectural Industrial Promotion Hall visible in the distance. National Archives photo.By July 1945, Germany had surrendered, and the war in Europe was over. Japan, however, refused to submit to the terms outlined in the Allies’ Potsdam Declaration. It appeared to American leaders that the only way to compel Japan’s unconditional surrender was to invade and conquer the Japanese home islands. Although an estimated 300,000 Japanese civilians had already died from starvation and bombing raids, Japan’s government showed no sign of capitulation. Instead, American intelligence intercepts revealed that by August 2, Japan had already deployed more than 560,000 soldiers and thousands of suicide planes and boats on the island of Kyushu to meet the expected American invasion of Japan. Additional reports correctly surmised that the Japanese military intended to execute all American prisoners in Japan in the event of an Allied landing. These frightening figures portended a costlier battle for the United States than any previously fought during the war. By comparison, US forces suffered 49,000 casualties, including 12,000 men killed in action, when facing less than 120,000 Japanese soldiers during the battle for the island of Okinawa from April to June of 1945. At least 110,000 Japanese soldiers and more than 100,000 Okinawan civilians, a third of the island’s prewar population, also perished in the campaign. American casualties on Okinawa weighed heavily on the minds of American planners who looked ahead to the invasion of Japan. Japan’s leaders hoped to prevail, not by defeating American forces, but by inflicting massive casualties and thereby breaking the resolve of the American public.This was the situation that confronted American President Harry S. Truman in the summer of 1945 when he authorized the use of the world’s first atomic bomb. In light of intelligence reports about Japan’s commitment to continue fighting, Truman and his military advisors were determined to use every weapon at their disposal in order to bring the war to an immediate end. Consequently, neither Truman nor any of his advisors ever debated if the atomic bombs should be used, only how and where they should be used. In the spring of 1945, the American government convened a committee of scientists and military officers to determine how best to use the bombs. This group unanimously declared that there was no guarantee that demonstrating the bombs to the Japanese in a deserted area would convince Japanese leaders to surrender. It was vital that Japan be convinced to surrender as fast as possible because the United States had just two atomic bombs available in July 1945 and additional weapons would not be ready to deploy for several more weeks. Meanwhile, thousands of Chinese, American, and Japanese soldiers continued to die each day the war continued.Consequently, Truman approved the long-standing plans for the US Army Air Force to drop atomic bombs on a list of preselected Japanese cities. The list of targets excluded Tokyo and Kyoto because of their political and historic importance. Instead, the intended target of the first bomb was Hiroshima, a fan-shaped city of approximately 550,000 people that occupied the estuary of the Ota River. The city was also home to the headquarters of the Japanese army that defended the island of Kyushu as well as a number of war industries.At 2:45 a.m. on Monday August 6, 1945, three American B-29 bombers of the 509th Composite Group took off from an airfield on the Pacific island of Tinian, 1,500 miles south of Japan. Colonel Paul Tibbets piloted the lead bomber, “Enola Gay,” which carried a nuclear bomb nicknamed “Little Boy.” Despite the bomb’s moniker, it weighed nearly 10,000 pounds. As a result, the overloaded Enola Gay used more than two miles of runway to get aloft. At 7:15 a.m., the bomber crew armed the bomb, and the plane began its ascent to the bombing altitude of 31,000 feet.

The B-29 Superfortress Enola Gay on the island of Tinian. US Army Air Force photo.Meanwhile, in Hiroshima, Reverend Kiyoshi Tanimoto awoke at 5 a.m. Hiroshima time, which was an hour behind Tinian time. Tanimoto was the pastor of the Hiroshima Methodist Church, and “a small man, quick to talk, laugh, and cry.” Tanimoto was a thoughtful and cautious man who had sent his wife and baby to the relative safety of a northern suburb. Tanimoto remained in the city to remove the transportable objects in his church to the safety of a suburban estate. He had slept poorly because of several air raid warnings the previous night. Hiroshima had not yet endured an American bombing raid, but its good fortune was not expected to last. That morning, Tanimoto had agreed to help a friend move a large armoire filled with clothes out to the suburbs. As the two men trundled the piece of furniture through the streets, they heard an air raid siren go off. The alarm sounded every morning when American weather planes flew overhead, so the men were not particularly worried. They continued on with their handcart through the city streets. When the pair reached their destination, “there was no sound of planes. The morning was still; the place was cool and pleasant.”At 8:14 a.m. Hiroshima time, the Enola Gay arrived over the city. The Aioi Bridge, which bombardier Thomas Ferebee used as an aiming point, was clearly visible through the plane’s bombsight. Ferebee took control of the bomber and opened the bomb bay doors. Just after 8:15 a.m., Ferebee released Little Boy from its restraints and the bomb fell away from the Enola Gay. The plane jumped nearly 10 feet at the sudden loss in weight. Tibbets immediately resumed control of the plane and banked it sharply on a 155 degree turn. He had practiced this difficult maneuver for months because he had been instructed that he had less than 45 seconds to get his plane clear of the subsequent explosion. Not even the scientists who designed the bomb were sure if the Enola Gay would survive the shock waves from the blast.Little Boy fell almost six miles in 43 seconds before detonating at an altitude of 2,000 feet. The bomb exploded with the force of more than 15,000 tons of TNT directly over a surgical clinic, 500 feet from the Aioi Bridge. Less than two percent of the bomb’s uranium achieved fission, but the resulting reaction engulfed the city in a blinding flash of heat and light. The temperature at ground level reached 7,000 degrees Fahrenheit in less than a second. The bomb vaporized people half a mile away from ground zero. Bronze statues melted, roof tiles fused together, and the exposed skin of people miles away burned from the intense infrared energy unleashed. At least 80,000 people died instantly.

A mushroom cloud rises over Hiroshima after the atomic bomb exploded at 9:15 AM on August 6, 1945. Photo by the Library of Congress.Reverend Tanimoto saw “a tremendous flash of light cut across the sky… from east to west, from the city toward the hills. It seemed a sheet of sun.” Because Tanimoto was two miles from the epicenter of the explosion, he had a few seconds to throw himself between two large rocks in the garden of his friend’s house. “He felt a sudden pressure, and then splinters and pieces of board and fragments of tile fell on him.” The house had collapsed, along with the concrete wall surrounding the garden. The day grew darker and darker under a massive dust cloud.

A view of Hiroshima after the bombing. National Archives photo.From the Enola Gay, Tibbets and his crew saw “a giant purple mushroom” that “had already risen to a height of 45,000 feet, three miles above our altitude, and was still boiling upward like something terribly alive.” Though the plane was already miles away, the cloud looked like it would engulf the bomber that had spawned it. “Even more fearsome,” to Tibbets, “was the sight on the ground below. At the base of the cloud, fires were springing up everywhere amid a turbulent mass of smoke that had the appearance of bubbling hot tar… The city we had seen so clearly in the sunlight a few minutes before was now an ugly smudge. It had completely disappeared under this awful blanket of smoke and fire.”

Destroyed fire trucks amid the wreckage of Hiroshima. National Archives photo.In the minutes, hours, and days that followed the bombing, survivors in Hiroshima tried desperately to locate loved ones and care for the thousands of wounded. Some people exhibited horrible burns, while others who outwardly appeared unscathed later died painful deaths from radiation poisoning. Thousands of people were buried in the debris of their homes. Most structures in the city had been constructed of wood with tile roofs. All but a handful of concrete structures in the city center had been completely leveled.

A Japanese burn victim of the atomic bombings. National Archives photo.President Harry Truman was aboard the cruiser USS Augusta on his way back from the Potsdam Conference when he learned of the bomb’s successful detonation. He immediately shared the news with his advisors and the ship’s crew. As the information was broadcast around the world, Allied soldiers around the globe felt as though they had received a reprieve from a death sentence. The end of World War II finally appeared to be in sight.

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atomic bomb: first testFirst atomic bomb test, near Alamogordo, New Mexico, July 16, 1945.(more)atomic bomb, Weapon whose great explosive power results from the sudden release of energy upon the splitting, or fission, of the nuclei of heavy elements such as plutonium or uranium (see nuclear fission). With only 11–33 lb (5–15 kg) of highly enriched uranium, a modern atomic bomb could generate a 15-kiloton explosion, creating a huge fireball, a large shock wave, and lethal radioactive fallout. The first atomic bomb, developed by the Manhattan Project during World War II, was set off on July 16, 1945, in the New Mexico desert. The only atomic bombs used in war were dropped by the U.S. on Hiroshima on Aug. 6, 1945, and on Nagasaki three days later. In 1949 the Soviet Union tested its first atomic bomb, followed by Britain (1952), France (1960), China (1964), India (1974), and Pakistan (1998). Israel and South Africa were suspected of testing atomic weapons in 1979. See also hydrogen bomb; Nuclear Non-proliferation Treaty; nuclear weapon.

Nagasaki Summary

Nagasaki, capital and largest city of Nagasaki ken (prefecture), western Kyushu, Japan, located at the mouth of the Urakami-gawa (Urakami River) where it empties into Nagasaki-kō (Nagasaki Harbour). The harbour is composed of a narrow, deep-cut bay, formed at the meeting point of Nomo-saki (Cape

Manhattan Project Summary

Manhattan Project, U.S. government research project (1942–45) that produced the first atomic bombs. See Britannica’s interactive timeline of the Manhattan Project. American scientists, many of them refugees from fascist regimes in Europe, took steps in 1939 to organize a project to exploit the

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J. Robert Oppenheimer American theoretical physicist and science administrator, noted as director of the Los Alamos Laboratory (1943–45) during development of the atomic bomb and as director of the Institute for Advanced Study, Princeton (1947–66). Accusations of disloyalty led to a government

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Vannevar Bush was an American electrical engineer and administrator who developed the Differential Analyzer and oversaw government mobilization of scientific research during World War II. The son of a Universalist minister, Bush received his bachelor’s and master’s degrees in mathematics from Tufts

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How understanding nature made the atomic bomb inevitable

A chain reaction of basic discoveries preceded the bombing of Hiroshima 75 years ago

By Tom Siegfried

Contributing Correspondent

August 6, 2020 at 6:00 am

75 years ago, on August 6, 1945, the United States dropped an atomic bomb on Hiroshima, Japan (shown). Three days later, another was dropped on Nagasaki.

509th Operations Group/Wikimedia Commons

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Atomic bombs hastened the end of World War II. But they launched another kind of war, a cold one, that threatened the entire planet with nuclear annihilation. So it’s understandable that on the 75th anniversary of the atomic bomb explosion that devastated Hiroshima (August 6, 1945), reflections tend to emphasize the geopolitical dramas during the decades that followed.

But it’s also worth reflecting on the scientific story of how the bombs came to be.

It’s not easy to pinpoint that story’s beginning. Nuclear fission — the source of the bomb’s energy — was discovered in 1938, less than seven years before Hiroshima. But the science behind nuclear energy originated decades earlier. You could say 1905, when Einstein revealed to the world that E = mc2. Or perhaps it’s better to begin with Henri Becquerel’s discovery of radioactivity in 1896. Radioactivity revealed a new sort of energy, of vast quantity, hidden within the most minuscule components of matter — the parts that made up atoms.

In any case, once science began to comprehend the subatomic world, no force could stop the eventual revelation of the atom’s power.

But the path from basic science to the bomb was not straightforward. There was no clear clue to how subatomic energy could be tapped for any significant use, military or otherwise. Writing in Science News Bulletin (the original Science News precursor) in 1921, physicist Robert Millikan noted that a gram of radium, in the process of disintegrating into lead, emits 300,000 times as much energy as burning a gram of coal. That wasn’t scary, Millikan said, because there wasn’t even enough radium in the world to make very much popcorn. But, he warned, “it is almost a foregone conclusion that similar stores of energy are also possessed by the atoms which … are not radioactive.”

In 1923 editor Edwin Slosson of Science News-Letter (the immediate precursor to Science News) also remarked that “all the elements have similar stores of energy if we only know how to release it.” But so far, he acknowledged, “scientists have not been able to unlock the atomic energy except by the employment of greater energy from another source.”

By then, physicists realized that the atom’s wealth of energy was stored in a nucleus — discovered by Ernest Rutherford in 1911. But accessing nuclear energy for practical use seemed unfeasible — at least to Rutherford, who in 1933 said that anyone planning to exploit nuclear energy was “talking moonshine.” But just the year before, the tool for releasing nuclear power had been discovered by James Chadwick, in the form of the subatomic particle known as the neutron.

Having no electric charge, the neutron was the ideal bullet to shoot into an atom, able to penetrate the nucleus and destabilize it. Such experiments in Italy by Enrico Fermi in the 1930s did actually induce fission in uranium. But Fermi thought he had created new, heavier chemical elements. He had no idea that the uranium nucleus had split. He concluded that he had produced a new element, number 93, heavier than uranium (element 92).

Not everyone agreed. Ida Noddack, a German chemist-physicist, argued that the evidence was inconclusive, and Fermi might have produced lighter elements, fragments of the uranium nucleus. But she was defying the prevailing wisdom. As the German chemist Otto Hahn wrote years later, the idea of breaking a uranium nucleus into smaller pieces was “wholly incompatible with the laws of atomic physics. To split heavy atomic nuclei into lighter ones was then considered impossible.”

Nevertheless Hahn and Lise Meitner, an Austrian physicist, continued bombarding uranium with neutrons, producing what they too believed to be new elements. Soon Meitner had to flee Germany for Sweden to avoid Nazi persecution of Jews. Hahn continued the work with chemist Fritz Strassmann; in December 1938 they found that an element they thought was radium could not be chemically distinguished from barium — apparently because it was barium. Hahn and Strassmann couldn’t explain how that could be.

Hahn wrote of this result to Meitner, who discussed it with her nephew Otto Frisch, a physicist studying at Niels Bohr’s institute in Copenhagen. Meitner and Frisch figured out what happened — the neutron had induced the uranium nucleus to split. Barium was one of the leftover chunks. Frisch told Bohr, about to board a ship to America, who realized instantly that fission confirmed his belief that an atomic nucleus behaved analogously to a drop of liquid. Upon arrival in the United States, Bohr began collaborating with John Archibald Wheeler at Princeton to explain the fission process. They quickly found that fission occurred much more readily in uranium-235, the rare form, than in the more common uranium-238. And their analysis revealed that an as yet undiscovered element, number 94, would also be especially efficient at fissioning. Their paper appeared on September 1, 1939, the day Germany invaded Poland to begin World War II.

Niels Bohr (left) and John Archibald Wheeler (right) collaborated to explain fission, the source of the atomic bomb’s energy.From left: Photograph by Paul Ehrenfest Jr., courtesy AIP Emilio Segrè Visual Archives, Weisskopf Collection; AIP Emilio Segrè Visual Archives

Between Bohr’s arrival in America in January 1939 and the publication of his paper with Wheeler, news of fission’s reality spread, stunning physicists and chemists around the world. At the end of January, for instance, word of fission reached Berkeley, where the leading physicist was J. Robert Oppenheimer, who eventually became the scientist that led the Manhattan Project to build the bomb.

Among the attendees at the Berkeley seminar introducing fission was Glenn Seaborg, a young chemistry instructor (who in 1941 discovered the unknown element 94 predicted by Bohr and Wheeler, naming it plutonium). Seaborg recalled that at first Oppenheimer didn’t believe fission happened. But, “after a few minutes he decided it was possible,” Seaborg said in a 1997 interview. “It just caught everybody by surprise.”

After the initial surprise, physicists quickly established that fission was the key to unlocking the atom’s energy storehouse. “Lots of people verified that indeed when uranium is bombarded by neutrons, slow neutrons in particular, a process occurs which releases tremendous amounts of energy,” physicist Hans Bethe said in a 1997 interview. Soon the implications for warfare occupied everybody’s attention.

“The threat of war was getting closer and closer,” Wheeler said in an interview in 1985. “It was impossible not to think about what this business (fission) could mean in the event of war.” In early 1939, physicists meeting to discuss fission concurred that a fission bomb was thinkable. “Everybody agreed that it was perfectly possible to make a nuclear explosive,” Bethe remembered.

Concerns that Germany might develop a nuclear bomb prompted Albert Einstein’s famous letter to President Franklin Roosevelt, sent in August 1939, that eventually led to the Manhattan Project. It became clear that building a fission bomb would require generating a “chain reaction” — the fission process itself would need to release neutrons capable of inducing further fission. In December 1942, Fermi led the team at the University of Chicago that demonstrated a sustained chain reaction, after which work on the bomb proceeded in Los Alamos, N.M., under Oppenheimer’s direction.

At first some physicists thought a bomb could not be developed rapidly enough to be relevant to the war. Bethe, for instance, preferred to work on radar.

“I had considered the whole enterprise a boondoggle,” he said. “I thought this had nothing to do with the war.” But by April 1943 Oppenheimer succeeded in recruiting Bethe to Los Alamos. By that time the science was in place, and the path to designing and building a bomb was straightforward. “All we had to do was to find out that there were no unforeseen difficulties,” Bethe said.

Ultimately the prototype was exploded at Alamogordo in July 1945, about three weeks before the bomb’s use against Japan.

The prototype atomic bomb was exploded at the Trinity test site, in Alamogordo, N.M., in July 1945.United States Department of Energy

It was a weapon more horrifying than anything humankind had ever encountered or imagined. And science was responsible. But only because science succeeded in understanding nature more deeply than before. Nobody knew at first where that understanding would lead.

There was absolutely no way to foresee that the discovery of radioactivity, or the atomic nucleus, or even the neutron would eventually enable the construction of a weapon of mass destruction. Yet once it was known that a bomb was possible, it was inevitable.

After Germany’s surrender in World War II, the Allies detained several top German scientists, including Werner Heisenberg, leader of the Nazi bomb project, and eavesdropped on their conversations. It was clear that the Germans failed to build a bomb because they did not think it was practically possible. But after hearing of the bombing of Hiroshima, Heisenberg was quickly able to figure out how the bomb had, in fact, been feasible. Once scientists know for sure something is possible, it’s a lot easier to do it.

In the case of the atomic bomb, basic research seeking nature’s secrets initiated a chain reaction of new knowledge, impossible to control. So the mushroom cloud that resulted symbolizes one of science’s most disturbing successes.

Questions or comments on this article? E-mail us at feedback@sciencenews.org | Reprints FAQ

About Tom Siegfried

Tom Siegfried is a contributing correspondent. He was editor in chief of Science News from 2007 to 2012 and managing editor from 2014 to 2017.

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imtoken国际版下载|atomic bomb

imtoken国际版下载|atomic bomb

Atomic Bomb: Nuclear Bomb, Hiroshima & Nagasaki - HISTORY

Atomic bombings of Hiroshima and Nagasaki | Date, Significance, Timeline, Deaths, & Aftermath | Britannica

Bombing of Hiroshima and Nagasaki - Causes, Impact & Lives Lost | HISTORY

The Most Fearsome Sight: The Atomic Bombing of Hiroshima | The National WWII Museum | New Orleans

atomic bomb summary | Britannica

Atomic bombings of Hiroshima and Nagasaki - The bombing of Nagasaki | Britannica

How understanding nature made the atomic bomb inevitable

Hiroshima Peace Memorial (Genbaku Dome) - UNESCO World Heritage Centre

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imtoken国际版下载|atomic bomb

imtoken国际版下载|atomic bomb

Atomic Bomb: Nuclear Bomb, Hiroshima & Nagasaki - HISTORY

Atomic bombings of Hiroshima and Nagasaki | Date, Significance, Timeline, Deaths, & Aftermath | Britannica

Bombing of Hiroshima and Nagasaki - Causes, Impact & Lives Lost | HISTORY

The Most Fearsome Sight: The Atomic Bombing of Hiroshima | The National WWII Museum | New Orleans

atomic bomb summary | Britannica

Atomic bombings of Hiroshima and Nagasaki - The bombing of Nagasaki | Britannica

How understanding nature made the atomic bomb inevitable

Hiroshima Peace Memorial (Genbaku Dome) - UNESCO World Heritage Centre

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