Atomic bombings of Hiroshima and Nagasaki

In 1945, the Pacific War between the Empire of Japan and the Allies entered its fourth year. Most Japanese military units fought fiercely, ensuring that the Allied victory would come at an enormous cost. The 1.25 million battle casualties incurred in total by the United States in World War II included both military personnel killed in action and wounded in action. Nearly one million of the casualties occurred during the last year of the war, from June 1944 to June 1945. In December 1944, American battle casualties hit an all-time monthly high of 88,000 as a result of the German Ardennes Offensive. Worried by the losses sustained, President Franklin D. Roosevelt suggested the use of atomic bombs on Germany as soon as possible, but was informed the first usable atomic weapons were still months away. America's reserves of manpower were running out. Deferments for groups such as agricultural workers were tightened, and there was consideration of drafting women. At the same time, the public was becoming war-weary, and demanding that long-serving servicemen be sent home. In the Pacific, the Allies returned to the Philippines, recaptured Burma, and invaded Borneo. Offensives were undertaken to reduce the Japanese forces remaining in Bougainville, New Guinea and the Philippines. In April 1945, American forces landed on Okinawa, where heavy fighting continued until June. Along the way, the ratio of Japanese to American casualties dropped from five to one in the Philippines to two to one on Okinawa. Although some Japanese soldiers were taken prisoner, most fought until they were killed or committed suicide. Nearly 99 percent of the 21,000 defenders of Iwo Jima were killed. Of the 117,000 Okinawan and Japanese troops defending Okinawa in April to June 1945, 94 percent were killed; 7,401 Japanese soldiers surrendered, an unprecedentedly large number. As the Allies advanced towards Japan, conditions became steadily worse for the Japanese people. Japan's merchant fleet declined from 5,250,000 gross register tons in 1941 to 1,560,000 tons in March 1945, and 557,000 tons in August 1945. The lack of raw materials forced the Japanese war economy into a steep decline after the middle of 1944. The civilian economy, which had slowly deteriorated throughout the war, reached disastrous levels by the middle of 1945. The loss of shipping also affected the fishing fleet, and the 1945 catch was only 22 percent of that in 1941. The 1945 rice harvest was the worst since 1909, and hunger and malnutrition became widespread. U.S. industrial production was overwhelmingly superior to Japan's. By 1943, the U.S. produced almost 100,000 aircraft a year, compared to Japan's production of 70,000 for the entire war.

What date did the atomic bombing of Hiroshima occur?

The atomic bombing of Hiroshima occurred on the 6th of August 1945. The Little Boy uranium bomb detonated at 08:15 local time over Shima Surgical Clinic.

Who was the pilot of the Enola Gay during the Hiroshima mission?

Colonel Paul Tibbets piloted the B-29 bomber named Enola Gay during the first atomic bombing mission. He took off from North Field on Tinian island and released the weapon after handing control to his bombardier Major Thomas Ferebee.

When was the second atomic bomb dropped on Nagasaki?

The second atomic bomb was dropped on Nagasaki on the 9th of August 1945. The Fat Man plutonium bomb was delivered by the aircraft Bockscar flown by Major Charles Sweeney.

How many people died in Hiroshima according to modern estimates?

Modern estimates by the Radiation Effects Research Foundation suggest that between 90,000 and 166,000 people died in Hiroshima by the end of 1945. Earlier United States surveys estimated approximately 66,000 dead and 69,000 injured immediately following the attack.

Why was Kyoto removed from the target list for the atomic bombings?

President Harry S Truman agreed with Secretary of War Henry Stimson to remove Kyoto from the target list due to its historical religious and cultural significance. Although General Leslie Groves attempted to restore it in July, Stimson remained adamant about sparing the city.

Target Selection Process

In April 1945, Marshall asked Groves to nominate specific targets for bombing for final approval by himself and Stimson. Groves formed a Target Committee, chaired by himself, that included Farrell, Major John A. Derry, Colonel William P. Fisher, Joyce C. Stearns and David M. Dennison from the USAAF; and scientists John von Neumann, Robert R. Wilson and William Penney from the Manhattan Project. The Target Committee met in Washington on the 27th of April; at Los Alamos on the 10th of May, where it was able to talk to the scientists and technicians there; and finally in Washington on the 28th of May, where it was briefed by Tibbets and Commander Frederick Ashworth from Project Alberta, and the Manhattan Project's scientific advisor, Richard C. Tolman. The Target Committee nominated five targets: Kokura (now Kitakyushu), the site of one of Japan's largest munitions plants; Hiroshima, an embarkation port and industrial center that was the site of a major military headquarters; Yokohama, an urban center for aircraft manufacture, machine tools, docks, electrical equipment and oil refineries; Niigata, a port with industrial facilities including steel and aluminum plants and an oil refinery; and Kyoto, a major industrial center. The target selection was subject to the following criteria: The target was larger than in diameter and was an important target in a large city. The blast wave would create effective damage. The target was unlikely to be attacked by August 1945. These cities were largely untouched during the nightly bombing raids, and the Army Air Forces agreed to leave them off the target list so accurate assessment of the damage caused by the atomic bombs could be made. Hiroshima was described as "an important army depot and port of embarkation in the middle of an urban industrial area. It is a good radar target and it is such a size that a large part of the city could be extensively damaged. There are adjacent hills which are likely to produce a focusing effect which would considerably increase the blast damage. Due to rivers it is not a good incendiary target." The Target Committee stated that "It was agreed that psychological factors in the target selection were of great importance. Two aspects of this are (1) obtaining the greatest psychological effect against Japan and (2) making the initial use sufficiently spectacular for the importance of the weapon to be internationally recognized when publicity on it is released.... Kyoto has the advantage of the people being more highly intelligent and hence better able to appreciate the significance of the weapon. Hiroshima has the advantage of being such a size and with possible focussing from nearby mountains that a large fraction of the city may be destroyed. The Emperor's palace in Tokyo has a greater fame than any other target but is of least strategic value." Edwin O. Reischauer, a Japan expert for the U.S. Army Intelligence Service, was incorrectly said to have prevented the bombing of Kyoto. In his autobiography, Reischauer specifically refuted this claim: Extant sources show that while Stimson was personally familiar with Kyoto, this was the result of a visit decades after his marriage when he was governor-general of the Philippines, not because he honeymooned there. On the 30th of May, Stimson asked Groves to remove Kyoto from the target list due to its historical, religious and cultural significance, but Groves pointed to its military and industrial significance. Stimson then approached President Harry S. Truman about the matter. Truman agreed with Stimson, and Kyoto was temporarily removed from the target list. Groves attempted to restore Kyoto to the target list in July, but Stimson remained adamant. On the 25th of July, Nagasaki was put on the target list in place of Kyoto. It was a major military port, one of Japan's largest shipbuilding and repair centers, and an important producer of naval ordnance.

Hiroshima Mission Execution

Hiroshima was the primary target of the first atomic bombing mission on the 6th of August, with Kokura and Nagasaki as alternative targets. The 393rd Bombardment Squadron B-29 Enola Gay, named after Tibbets's mother and piloted by Tibbets, took off from North Field, Tinian, about six hours' flight time from Japan, at 02:45 local time. Enola Gay was accompanied by two other B-29s: The Great Artiste, commanded by Major Charles Sweeney, which carried instrumentation, and a then-nameless aircraft later called Necessary Evil, commanded by Captain George Marquardt. Necessary Evil was the photography aircraft. After leaving Tinian, the aircraft made their way separately to Iwo Jima to rendezvous with Sweeney and Marquardt at 05:55 at , and set course for Japan. The aircraft arrived over Hiroshima in clear visibility at . Parsons, who was in command of the mission, armed the bomb in flight to minimize the risks during takeoff. He had witnessed four B-29s crash and burn at takeoff, and feared that a nuclear explosion would occur if a B-29 crashed with an armed Little Boy on board. His assistant, Second Lieutenant Morris R. Jeppson, removed the safety devices 30 minutes before reaching the target area. During the night of 5, the 6th of August, Japanese early warning radar detected the approach of numerous American aircraft headed for the southern part of Japan. Radar detected 65 bombers headed for Saga, 102 bound for Maebashi, 261 en route to Nishinomiya, 111 headed for Ube and 66 bound for Imabari. An alert was given and radio broadcasting stopped in many cities, among them Hiroshima. The all-clear was sounded in Hiroshima at 00:05. About an hour before the bombing, the air raid alert was sounded again, as Straight Flush flew over the city. It broadcast a short message, which was picked up by Enola Gay. It read: "Cloud cover less than 3/10th at all altitudes. Advice: bomb primary." The all-clear was sounded over Hiroshima again at 07:09. At 08:09, Tibbets started his bomb run and handed control over to his bombardier, Major Thomas Ferebee. The release at 08:15 (Hiroshima time) went as planned, and the Little Boy containing about of uranium-235 took 44.4 seconds to fall from the aircraft flying at about to a detonation height of about above the city. describes how various values were recorded for the B-29's altitude at the moment of bomb release over Hiroshima. The strike report said , the official history said , Parson's log entry was , and the navigator's log was , the latter possibly an error transposing two digits. A later calculation using the indicated atmospheric pressure arrived at the figure of . Similarly, several values have been reported as the altitude of the Little Boy bomb at the moment of detonation. Published sources vary in the range of above the city. The device was set to explode at , but this was approximate. Malik uses the figure of plus or minus , determined after data review by . Radar returns from the tops of multistory buildings near the hypocenter may have triggered the detonation at a somewhat higher altitude than planned. Kerr et al. (2005) found that a detonation altitude of , plus or minus , gave the best fit for all the measurement discrepancies. Enola Gay was away before it felt the shock waves from the blast. Due to crosswind, the bomb missed the aiming point, the Aioi Bridge, by approximately and detonated directly over Shima Surgical Clinic. It released energy equivalent to , four times the tonnage of conventional bombs that had wiped out the city of Dresden in Germany. The weapon was very inefficient, with only 1.7 percent of its material fissioning. The radius of total destruction was about , with resulting fires across . Enola Gay stayed over the target area for two minutes and was away when the bomb detonated. Only Tibbets, Parsons, and Ferebee knew of the nature of the weapon; the others on the bomber were only told to expect a blinding flash and given protective goggles. "It was hard to believe what we saw", Tibbets told reporters, while Parsons said "the whole thing was tremendous and awe-inspiring... the men aboard with me gasped 'My God'." He and Tibbets compared the shockwave to "a close burst of ack-ack fire". Necessary Evils cameras all failed; the only film of the attack was made by a 16mm cine camera smuggled onto the aircraft by a crew member. Enola Gays crew received a heroes' welcome on landing at Tinian, with hundreds of cheering welcomers and "more generals than I'd ever seen in my life. We wondered what the hell they were doing there" according to navigator Theodore "Dutch" Van Kirk. When Tibbets stepped from his B-29 the Distinguished Service Cross was unexpectedly pinned to his chest while he was still holding his pipe.

Nagasaki Mission Execution

According to a crew member, Hiroshima had been "the perfect mission" where everything went right, whereas in the Nagasaki mission, almost everything would go wrong. Responsibility for the timing of the second bombing was delegated to Tibbets. Scheduled for the 11th of August, the raid was moved earlier by two days to avoid a five-day period of bad weather forecast to begin on the 10th of August. Three bomb pre-assemblies had been transported to Tinian, labeled F-31, F-32, and F-33 on their exteriors. On the 8th of August, a dress rehearsal was conducted off Tinian by Sweeney using Bockscar as the drop airplane. Assembly F-33 was expended testing the components and F-31 was designated for the 9th of August mission. At 03:47 Tinian time (GMT+10), 02:47 Japanese time, on the morning of the 9th of August 1945, Bockscar, flown by Sweeney's crew, lifted off from Tinian island with the Fat Man, with Kokura as the primary target and Nagasaki the secondary target. The mission plan for the second attack was nearly identical to that of the Hiroshima mission, with two B-29s flying an hour ahead as weather scouts and two additional B-29s in Sweeney's flight for instrumentation and photographic support of the mission. Sweeney took off with his weapon partially armed, but with the electrical safety plugs still engaged; arming was completed a few minutes after takeoff. During pre-flight inspection of Bockscar, the flight engineer notified Sweeney that an inoperative fuel transfer pump made it impossible to use of fuel carried in a reserve tank. This fuel would still have to be carried all the way to Japan and back, consuming still more fuel. Replacing the pump would take hours; moving the Fat Man to another aircraft might take just as long and was dangerous as well, as the bomb was live. Tibbets and Sweeney therefore elected to have Bockscar continue the mission as the reserve fuel was not expected to be needed. This time Penney and Cheshire were allowed to accompany the mission, flying as observers on the third plane, Big Stink, flown by the group's operations officer, Major James I. Hopkins, Jr. Observers aboard the weather planes reported both targets clear. The aircraft ran into thunderstorms, with the fully armed bomb on board. Unexpectedly a white light on the bomb control panel came on that normally illuminates when the bomb is about to.

Human Cost And Aftermath

Events on the ground People on the ground reported a , a brilliant flash of light, followed by a , a loud booming sound. The experiences of survivors in the city varied depending on their location and circumstances, but a common factor in survivor accounts was a sense that a conventional weapon (sometimes cited as a magnesium bomb, which has a distinctively bright white flash) had happened to go off immediately in their vicinity, causing tremendous damage (throwing people across rooms, breaking glass, crushing buildings). After emerging from the ruins, the survivors gradually understood that the entire city had been attacked at the same instant. Survivor accounts frequently feature walking through the ruins of the city without a clear sense of where to go, and encountering the cries of people trapped within crushed structures, or people with horrific burns. As the numerous small fires created by the blast began to grow, they merged into a firestorm that moved quickly throughout the ruins, killing many who had been trapped, and causing people to jump into Hiroshima's rivers in search of sanctuary (many of whom drowned). The photographer Yoshito Matsushige took the only photographs of Hiroshima immediately after the bombing. He described in a later interview that, immediately after the bombing, "everywhere there was dust; it made a grayish darkness over everything." He took five photographs in total before he could not continue: "It was really a terrible scene. It was just like something out of hell." Survivor accounts also prominently feature cases of survivors who appeared uninjured, but who would succumb within hours or days to what would later be identified as radiation sickness. Estimating the number of people killed by the blast, firestorm, and radiation effects of the bombing has been hampered by imprecise record-keeping during the war, the chaos caused by the attack, uncertainty about the number of people in the city on the morning of the attack, and variations in methodology. Reports by the Manhattan Project in 1946 and the U.S. occupation, led Joint Commission for the Investigation of the Atomic Bomb in Japan in 1951 estimated 66,000 dead and 69,000 injured, and 64,500 dead and 72,000 injured, respectively, while Japanese-led reconsiderations of the death toll in the 1970s estimated 140,000 dead in Hiroshima by the end of the year. Estimates also vary on the number of Japanese military personnel killed. The United States Strategic Bombing Survey estimated in 1946 that there were 24,158 soldiers present in Hiroshima at the time of the attack, and that 6,789 were killed or missing as a result; the 1970s reconsiderations estimated about 10,000 military dead. A modern estimate by the Radiation Effects Research Foundation (RERF) estimates a city population of 340,000 to 350,000 at the time of the bombing, of which 90,000 to 166,000 died by the end of the year. U.S. surveys estimated that of the city were destroyed. Japanese officials determined that 69 percent of Hiroshima's buildings were destroyed and another 6 to 7 percent damaged. Some of the reinforced concrete buildings in Hiroshima had been very strongly constructed because of the earthquake danger in Japan, and their framework did not collapse even though they were fairly close to the blast center. Since the bomb detonated in the air, the blast was directed more downward than sideways, which was largely responsible for the survival of the Prefectural Industrial Promotional Hall, now commonly known as the Genbaku (A-bomb) dome, which was only from ground zero (the hypocenter). The ruin was named Hiroshima Peace Memorial and was made a UNESCO World Heritage Site in 1996 over the objections of the United States and China, which expressed reservations on the grounds that other Asian nations were the ones who suffered the greatest loss of life and property, and a focus on Japan lacked historical perspective. For decades this photo was misidentified as the mushroom cloud of the bomb that formed at c. 08:16. However, due to its much greater height, the scene was identified in March 2016 as the firestorm-cloud that engulfed the city, some three hours after the bombing. The air raid warning had been cleared at 07:31, and many people were outside, going about their activities. Eizō Nomura was the closest known survivor, being in the basement of a reinforced concrete building (it remained as the Rest House after the war) only from ground zero at the time of the attack. He died in 1982, aged 84. Akiko Takakura was among the closest survivors to the hypocenter of the blast. She was in the solidly-built Bank of Hiroshima only from ground-zero at the time of the attack. Over 90 percent of the doctors and 93 percent of the nurses in Hiroshima were killed or injured, most had been in the downtown area which received the greatest damage. The hospitals were destroyed or heavily damaged. Only one doctor, Terufumi Sasaki, remained on duty at the Red Cross Hospital. Nonetheless, by early afternoon the police and volunteers had established evacuation center at hospitals, schools and tram stations, and a morgue was established in the Asano library. Survivors of the blast gathered for medical treatment, but many would die before receiving any help, leaving behind rings of corpses around hospitals. Most elements of the Japanese Second General Army headquarters were undergoing physical training on the grounds of Hiroshima Castle, barely from the hypocenter. The attack killed 3,243 troops on the parade ground. The communications room of Chugoku Military District Headquarters that was responsible for issuing and lifting air raid warnings was located in a semi-basement in the castle. Yoshie Oka, a Hijiyama Girls High School student who had been mobilized to serve as a communications officer, had just sent a message that the alarm had been issued for Hiroshima and neighboring Yamaguchi when the bomb exploded. She used a special phone to inform Fukuyama Headquarters (some away) that "Hiroshima has been attacked by a new type of bomb. The city is in a state of near-total destruction." Since Mayor Senkichi Awaya had been killed at the mayoral residence, Field Marshal Shunroku Hata, who was only slightly wounded, took over the administration of the city and coordinated relief efforts. Many of his staff had been killed or fatally wounded, including Lieutenant Colonel Yi U, a prince of the Korean imperial family who was serving as a General Staff Officer. Hata's senior surviving staff officer was the wounded Colonel Kumao Imoto, who acted as his chief of staff. Soldiers from the undamaged Hiroshima Ujina Harbor used s, intended to repel the American invasion, to collect the wounded and take them down the rivers to the military hospital at Ujina. Trucks and trains brought in relief supplies and evacuated survivors from the city. Twelve American airmen were imprisoned at the Chugoku Military Police Headquarters, about from the hypocenter of the blast. Most died instantly, although two were reported to have been executed by their captors, and two prisoners badly injured by the bombing were left next to the Aioi Bridge by the Kempeitai, where they were stoned to death. Eight U.S. prisoners of war killed as part of the medical experiments program at Kyushu University were falsely reported by Japanese authorities as having been killed in the atomic blast as part of an attempted cover up. The fires created by the atomic bomb detonation carried large amounts of ash into the clouds in the atmosphere. One to two hours after the explosion, a "black rain" fell as a tarry combination of ash, radioactive fallout, and water, causing severe radiation burns in some cases.

Surrender And War End

Japanese realization of the bombing The Tokyo control operator of the Japan Broadcasting Corporation noticed that the Hiroshima station had gone off the air. He tried to re-establish his program by using another telephone line, but it too had failed. About 20 minutes later the Tokyo railroad telegraph center realized that the main line telegraph had stopped working just north of Hiroshima. From some small railway stops within of the city came unofficial and confused reports of a terrible explosion in Hiroshima. All these reports were transmitted to the headquarters of the Imperial Japanese Army General Staff. Military bases repeatedly tried to call the Army Control Station in Hiroshima. The complete silence from that city puzzled the General Staff; they knew that no large enemy raid had occurred and that no sizable store of explosives was in Hiroshima at that time. A young officer was instructed to fly immediately to Hiroshima, to land, survey the damage, and return to Tokyo with reliable information for the staff. It was felt that nothing serious had taken place and that the explosion was just a rumor. The staff officer went to the airport and took off for the southwest. After flying for about three hours, while still nearly from Hiroshima, he and his pilot saw a great cloud of smoke from the firestorm created by the bomb. After circling the city to survey the damage they landed south of the city, where the staff officer, after reporting to Tokyo, began to organize relief measures. Tokyo learned that the city had been destroyed by a new type of bomb from President Truman's announcement of the strike, sixteen hours later. The official White House announcement was delayed by congestion on circuits from Tinian, which meant that Groves could not initially confirm the extent of the damage to Hiroshima. The first report from Hiroshima was sent on a hotline by a fourteen-year old female student volunteer communications officer Yoshie Okawa in a bunker at the Chugoku Military District Headquarters, half a mile (800m) from the epicentre. She was not believed at Fukuyama, so she found a soldier above ground who told her that Hiroshima has been attacked by a new type of bomb. The city is in a state of near-total destruction. Events of 7, the 9th of August Sixteen hours after the Hiroshima bombing, a statement was issued by the White House staff in Truman's name announcing the use of the new weapon. The speech was not written by Truman, but largely drafted by Arthur W. Page, with modifications from the members of the Interim Committee. Truman read a version of it on the to news cameras shortly afterwards. It said that the United States and its allies had "spent two billion dollars on the greatest scientific gamble in history, and won," and warned Japan: "If they do not now accept our terms, they may expect a rain of ruin from the air, the like of which has never been seen on this earth. Behind this air attack will follow sea and land forces in such numbers and power as they have not yet seen and with the fighting skill of which they are already well aware." This was a widely broadcast speech picked up by Japanese news agencies. The 50,000-watt standard wave station on Saipan, the OWI radio station, broadcast a similar message to Japan every 15 minutes about Hiroshima, stating that more Japanese cities would face a similar fate in the absence of immediate acceptance of the terms of the Potsdam Declaration and emphatically urged civilians to evacuate major cities. Radio Japan, which continued to extoll victory for Japan by never surrendering had informed the Japanese of the destruction of Hiroshima by a single bomb. Soviet Foreign Minister Vyacheslav Molotov had informed Tokyo of the Soviet Union's unilateral abrogation of the Soviet, Japanese Neutrality Pact on the 5th of April. At two minutes past midnight on the 9th of August, Tokyo time, Soviet infantry, armor, and air forces had launched the Manchurian Strategic Offensive Operation. Four hours later, word reached Tokyo of the Soviet Union's official declaration of war. The senior leadership of the Japanese Army began preparations to impose martial law on the nation, with the support of Minister of War Korechika Anami, to stop anyone attempting to make peace. On the 7th of August, a day after Hiroshima was destroyed, Yoshio Nishina and other atomic physicists arrived at the city, and carefully examined the damage. They then went back to Tokyo and told the cabinet that Hiroshima was indeed destroyed by a nuclear weapon. Admiral Soemu Toyoda, the Chief of the Naval General Staff, estimated that no more than one or two additional bombs could be readied, so they decided to endure the remaining attacks, acknowledging "there would be more destruction but the war would go on". American Magic codebreakers intercepted the cabinet's messages. Purnell, Parsons, Tibbets, Spaatz, and LeMay met on Guam that same day to discuss what should be done next. Since there was no indication of Japan surrendering, they decided to proceed with dropping another bomb. Parsons said that Project Alberta would have it ready by the 11th of August, but Tibbets pointed to weather reports indicating poor flying conditions on that day due to a storm, and asked if the bomb could be readied by the 9th of August. Parsons agreed to try to do so.