Nine Harrowing Eyewitness Accounts of the Bombings of Hiroshima and Nagasaki

Senior Associate Digital Editor, History

When photographer Haruka Sakaguchi first tried to connect with survivors of the atomic bombings of Hiroshima and Nagasaki, her cold calls and emails went unanswered. Then, in 2017, the Brooklyn-based artist decided to visit Japan herself in hopes of meeting someone who knew a hibakusha—the Japanese word for those affected by the August 1945 attacks.

“I sat at the Nagasaki Peace Park for hours trying to differentiate between tourists and locals who were visiting to pray for a loved one—they often wore juzu, or prayer beads,” says Sakaguchi, who immigrated to the U.S. from Japan as an infant in the 1990s. After five hours of people watching, she struck up a conversation with the daughter of a survivor, who agreed to introduce her to eight hibakusha.

Elizabeth Chappell, an oral historian at the Open University in the United Kingdom, encountered similar difficulties after setting out to catalog atomic bomb survivors’ testimony. “When you have a silenced group like that, they have a very internal culture,” she explains. “They’re very protective of their stories. I was told I wouldn’t get interviews.”

Survivors’ reluctance to discuss their experiences stems in large part from the stigma surrounding Japan’s hibakusha community. Due to a limited understanding of radiation poisoning’s long-term effects, many Japanese avoided (or outright abused) those affected out of fear that their ailments were contagious. This misconception, coupled with a widespread unwillingness to revisit the bombings and Japan’s subsequent surrender, led most hibakusha to keep their trauma to themselves. But in the past decade or so, documentary efforts like Sakaguchi’s 1945 Project and Chappell’s The Last Survivors of Hiroshima have become increasingly common—a testament to both survivors’ willingness to defy the long-standing culture of silence and the pressing need to preserve these stories as hibakusha’s numbers dwindle.

Aerial views of Hiroshima before and after the bombing — Aerial views of Hiroshima before (left) and after (right) the bombing Public domain via Wikimedia Commons

When planning for the war in the Pacific's next phase, the U.S. invasion of mainland Japan, the Truman administration estimated that American casualties would be between 1.7 and 4 million, while Japanese casualties could number up to 10 million. Per the National WWII Museum, U.S. intelligence officers warned that “there are no civilians in Japan,” as the imperial government had strategically made newly mobilized combatants’ attire indistinguishable from civilians. They also predicted that Japanese soldiers and civilians alike would choose to fight to the death rather than surrender.

Throughout World War II, the Japanese code of bushido, or “way of the warrior,” guided much of Emperor Hirohito’s strategy. With its actions in China, the Philippines, the surprise attack on Pearl Harbor and elsewhere in Asia, the Imperial Japanese army waged a brutal, indiscriminate campaign against enemy combatants, civilians and prisoners of war. Prizing sacrifice, patriotism and loyalty above all else, the bushido mindset led Japanese soldiers to view their lives as expendable in service of the emperor and consider suicide more honorable than yielding to the enemy. Later in the war, as American troops advanced on the Japanese mainland, civilians indoctrinated to believe that U.S. soldiers would torture and kill those who surrendered also started engaging in mass suicides. The Battle of Okinawa was a particularly bloody example of this practice, with Japanese soldiers even distributing hand grenades to civilians caught in the crossfire.

The accuracy of the U.S. government’s projections, and the question of whether Emperor Hirohito would have surrendered without the use of atomic weapons, is the subject of great historical debate. But the facts remain: When the bombing of Hiroshima failed to produce Japan’s immediate surrender, the U.S. moved forward with plans to drop a second atomic bomb on Nagasaki. That same week, the Soviet Union officially declared war on Japan after years of adhering to a 1941 neutrality pact.

In total, the August 6 and 9 bombings of Hiroshima and Nagasaki, respectively, killed more than 200,000 people. Six days after the second attack, Hirohito announced Japan’s unconditional surrender. The American occupation of Japan, which set out to demilitarize the country and transform it into a democracy, began soon after.

Nagasaki, as seen in the aftermath of the August 9 bombing Photo by Roger Viollet via Getty Images

An estimated 650,000 people survived the atomic blasts, only to find their post-war lives marred by health issues and marginalization. Hibakusha received little official aid from the temporary occupying government, as American scientists’ understanding of radiation’s effects was only “marginally better” than that of the Japanese, according to the Atomic Heritage Foundation. In September 1945, the New York Times reported that the number of Japanese people who’d died of radiation “was very small.”

Survivors faced numerous forms of discrimination. Survivor Shosho Kawamoto, for instance, proposed to his girlfriend more than a decade after the bombing, but her father forbade the marriage out of fear that their children would bear the brunt of his radiation exposure. Heartbroken, Kawamoto vowed to remain unmarried for the rest of his life.

“Widespread fears that hibakusha are physically or psychologically impaired and that their children might inherit genetic defects stigmatize first- and second-generation hibakusha to this day, especially female survivors,” Sakaguchi says. (Scientists who monitored almost all pregnancies in Hiroshima and Nagasaki between 1948 and 1954 found no “statistically significant” increase in birth defects.)

Sakaguchi also cites accounts of workplace discrimination: Women with visible scars were told to stay home and avoid “front-facing work,” while those issued pink booklets identifying them as hibakusha—and indicating their eligibility for healthcare subsidies—were often refused work due to fears of future health complications. Many hibakusha interviewed for the 1945 Project avoided obtaining this paperwork until their children were “gainfully employed [and] married or they themselves became very sick” in order to protect their loved ones from being ostracized.

Hiroshima Peace Memorial Park — This building, now preserved as the Hiroshima Peace Memorial, was the only structure left standing near the bomb’s hypocenter. Photo by Eric Lafforgue / Art in All of Us / Corbis via Getty Images

Perhaps the most jarring aspect of hibakusha’s experiences was the lack of recognition afforded to survivors. As Chappell explains, far from reversing the empire’s decades-long policy of strict censorship, U.S. officials in charge of the postwar occupation continued to wield control of the press, even limiting use of the Japanese word for atomic bomb: genbaku. After the Americans left in 1952, Japan’s government further discounted hibakusha, perpetuating what the historian deems “global collective amnesia.” Even the 1957 passage of legislation providing benefits for hibakusha failed to spark meaningful discussion—and understanding—of survivors’ plight.

Writing in 2018, Chappell added, “[T]he hibakusha were the unwelcome reminder of an unknown, unclassifiable event, something so unimaginable society tried to ignore it.”

More recently, aging hibakusha have grown more vocal about their wartime experiences. They share their stories in hopes of helping the next “generations imagine a different kind of future,” according to Chappell, and to plead for nuclear disarmament, says Sakaguchi. Many organizations dedicated to preserving survivors’ testimony—the Hiroshima Peace Memorial Museum, the Nagasaki Atomic Bomb Museum and the Hiroshima Peace Culture Foundation, among others—were actually founded by hibakusha: “They had to be the first researchers, [and] they had to be their own researchers,” Chappell notes.

Today, hibakusha still face widespread discrimination. Several individuals who agreed to participate in Sakaguchi’s 1945 Project later withdrew, citing fears that friends and colleagues would see their portraits. Still, despite fear of retaliation, survivors continue to speak out. Below, find nine such firsthand accounts of the bombings of Hiroshima and Nagasaki, collected here to mark the 75th anniversary of the attacks.

This article contains graphic depictions of the atomic bombings’ aftermath. The survivor quotes chosen from interviews with Sakaguchi were spoken in Japanese and translated by the photographer.

Taeko Teramae

Hiroshima survivor Taeko Teramae didn’t realize the full extent of her injuries until her younger brothers started making fun of her appearance. Confused, the 15-year-old asked her parents for a mirror—a request they denied, leading her to surreptitiously track one down on a day they’d left the house.

“I was so surprised I found my left eye looked just like a pomegranate, and I also found cuts on my right eye and on my nose and on my lower jaw,” she recalled. “It was horrible. I was very shocked to find myself looking like a monster.”

On the day of the bombing, Teramae was one of thousands of students mobilized to help fill Hiroshima’s wartime labor shortages. Assigned to the city’s Telephone Bureau, she was on the building’s second floor when she heard a “tremendous noise.” The walls collapsed, momentarily blanketing the workers in darkness. “I began to choke on the consequent smoke— poisonous gas, it seemed like—and vomited uncontrollably,” wrote Teramae in a 1985 article for Heiwa Bunka magazine.

Amid the din of cries for help, a single voice called out: “We must endure this, like the proud scholars that we are!” It was Teramae’s homeroom teacher, Chiyoko Wakita, who was herself not much older than her students. Comforted by Wakita’s words, the children gradually quieted down.

Teramae managed to escape by jumping out of a second-story window and climbing down a telephone pole. But when she tried to cross the Kyobashi River to safety, she found its only bridge in flames and the city she’d left behind “engulfed in a sea of fire.” Once again, Wakita came to her charge’s rescue, accompanying her on the swim across the river and offering encouragement throughout the arduous journey. After dropping Teramae off at an evacuation center, the young teacher returned to Hiroshima to help her other students. She died of her injuries on August 30.

“[Wakita] saved my life, yet I was not able to tell her a simple ‘thank you,’” Teramae later said. “I deeply regret this, to this day.”

Sachiko Matsuo

Sometime before the bombing of Nagasaki, 11-year-old Sachiko Matsuo’s father happened upon a leaflet dropped by American pilots to warn the city’s residents of an imminent attack. Taking the message seriously, he constructed a makeshift cabin high up on a mountain overlooking Nagasaki and, in the days leading up to the scheduled bombing, implored his extended family to take shelter there from morning until evening. But when August 8—the supposed day of the attack—passed without incident, Matsuo’s mother and aunt told him they wanted to stay home.

Reflecting on the argument that followed in an interview with Sakaguchi, Matsuo said her father demanded that the pair return to the barracks, pointing out that the United States’ time zone was one day behind Japan’s. “When they opposed, he got very upset and stormed out to go to work,” she added. Meanwhile, his remaining family members “changed our minds and decided to hide out in the barrack for one more day.” The bomb struck just hours later. All those hidden in the cabin survived the initial impact, albeit with a number of severe burns and lacerations.

“After a while, we became worried about our house, so I walked to a place from where I would be able to see the house, but there was something like a big cloud covering the whole city, and the cloud was growing and climbing up toward us,” Matsuo explained in 2017. “I could see nothing below. My grandmother started to cry, ‘Everybody is dead. This is the end of the world.’”

Matsuo’s father, who’d been stationed outside of an arms factory with his civil defense unit when the bomb struck, returned to the cabin that afternoon. He’d sustained several injuries, including wounds to the head, hands and legs, and required a cane to walk. His eldest son, who’d also been out with a civil defense unit, died in the blast. The family later spotted his corpse resting on a rooftop, but by the time they returned to retrieve it, the body was gone.

In the weeks after the bombing, Matsuo’s father began suffering from the effects of radiation. “He soon came down with diarrhea and a high fever,” she told Sakaguchi. “His hair began to fall out and dark spots formed on his skin. My father passed away—suffering greatly—on August 28.”

Norimitsu Tosu

Every morning, Norimitsu Tosu’s mother took him and his twin brother on a walk around their Hiroshima neighborhood. August 6 was no different: The trio had just returned from their daily walk, and the 3-year-olds were in the bathroom washing their hands. Then, the walls collapsed, trapping the brothers under a pile of debris. Their mother, who’d briefly lost consciousness, awoke to the sound of her sons’ cries. Bleeding “all over,” Tosu told the National Catholic Reporter’s David E. DeCosse in 2016, she pulled them from the rubble and brought them to a relative’s house.

Five of Tosu’s seven immediate family members survived the bombing. His father, temporarily jailed over an accusation of bribery, was shielded by the prison’s strong walls, but two siblings—an older brother named Yoshihiro and a sister named Hiroko—died. The family was only able to learn of Yoshihiro’s fate: According to Tosu, “We didn't know what happened to [Hiroko], and we never located her body. Nothing. We didn't even know where exactly she was when the bomb exploded.”

Given his age at the time of the attack, Tosu doesn’t remember much of the actual aftermath. But as he explained to grandson Justin Hsieh in 2019, one memory stands out:

When we were evacuating, there were dead horses, dogs, animals and people everywhere. And the smells I remember. There was this terrible smell. It smelled like canned salmon. So for a long time after that, I couldn’t eat canned salmon because the smell reminded me of that. It was sickening. So more than anything I saw or heard, it was the smell that I remember the most.

Yoshiro Yamawaki

The day after the U.S. dropped an atomic bomb on Nagasaki, 11-year-old Yoshiro Yamawaki went out in search of his father, who had failed to return from a shift at the local power station. On the way to the factory, Yamawaki and two of his brothers saw unspeakable horrors, including corpses whose “skin would come peeling off just like that of an over-ripe peach, exposing the white fat underneath”; a young woman whose intestines dragged behind her in what the trio at first thought was a long white cloth belt; and a 6- or 7-year-old boy whose parasitic roundworms had come “shooting out” of his mouth post-mortem.

The boys soon arrived at the power station, which was situated near the bomb’s hypocenter and had been reduced to little more than a pile of scorched metal. Spotting three men with shovels, they called out, “Our name is Yamawaki. Where is our father?” In response, one of the men pointed toward a demolished building across the street and simply said, “Your father is over there.”

Joy quickly turned to anguish as the brothers spotted their father’s corpse, “swollen and scorched just like all the others.” After consulting with the older men, they realized that they’d need to either cremate his remains to bring home to their mother or bury his body onsite. Unsure what else to do, they gathered smoldering pieces of wood and built a makeshift funeral pyre.

The men advised the brothers to come back for their father’s ashes the following day. Too overcome with emotion to remain, they agreed. But upon returning to the factory the following morning, they found their father’s half-cremated body abandoned and coated in ash.

“My brother looked at our father's body for a while longer, and then said, ‘We can't do anything more. We’ll just take his skull home and that will be the end,’” Yamawaki recalled at age 75.

When the young boy went to retrieve the skull with a pair of tongs brought from home, however, “it crumbled apart like a plaster model and the half-burned brains came flowing out.”

“Letting out a scream, my brother threw down the tongs, and darted away,” said Yamawaki. “The two of us ran after him. [These] were the circumstances under which we forsook our father's body.”

Sakaguchi, who photographed Yamawaki for the 1945 Project, offers another perspective on the incident, saying, “Aside from the traumatic experience of having to cremate your own father, I was awestruck by Mr. Yamawaki and his brothers’ persistence—at a young age, no less—to send their father off with quietude and dignity under such devastating circumstances.”

Kikue Shiota

August 6 was “an unimaginably beautiful day” punctuated by a “blinding light that flashed as if a thousand magnesium bulbs had been turned on all at once,” Hiroshima survivor Kikue Shiota later recalled. The blast trapped 21-year-old Shiota and her 16-year-old sister beneath the remains of their razed house, more than a mile from the bomb’s hypocenter.

After Shiota’s father rescued his daughters from the rubble, they set out in search of their remaining family members. Burned bodies were scattered everywhere, making it impossible to walk without stepping on someone. The sisters saw a newborn baby still attached to its dead mother’s umbilical cord lying on the side of the road.

As the pair walked the streets of Hiroshima, their 10-year-old brother conducted a similar search. When Shiota finally spotted him standing among a crowd of people, she was horrified: “All the skin on his face was peeling off and dangling,” she said. “He was limping feebly, all the skin from his legs burned and dragging behind him like a heap of rags.”

The young boy survived his injuries. His 14-year-old sister, Mitsue, did not. Though the family never recovered her body, they were forced to face the worst after finding a scrap of Mitsue’s school uniform burned into the asphalt.

“I thought my heart would surely stop because the very cloth I found was my sister’s, Mitsue, my little sister,” Shiota remembered. “‘Mi-chan!’ I called out to her. ‘It must have been terribly hot. The pain must have been unbearable. You must have screamed for help.’ … My tears falling, I searched for my sister in vain.”

One month after the bombing, the family lost another loved one: Shiota’s mother, who had appeared to be in good health up until the day before her passing, died of acute leukemia caused by the blast’s radioactive rays. She was cremated in a pit dug by a neighbor as her grief-stricken daughter looked on.

Akiko Takakura

Decades after the bombing of Hiroshima, the image of a man whose charred fingertips had been engulfed in blue flames remained imprinted in Akiko Takakura’s memory. “With those fingers, the man had probably picked up his children and turned the pages of books,” the then-88-year-old told the Chugoku Shimbun in 2014. The vision so haunted Takakura that she immortalized it in a 1974 drawing and recounted it to the many schoolchildren she spoke to as a survivor of the August 6 attack. “More than 50 years later, / I remember that blue flame, / and my heart nearly bursts / with sorrow,” she wrote in a poem titled “To Children Who Don’t Know the Atomic Bomb.”

Takakura was 19 years old when the bomb fell, detonating above a quiet street close to her workplace, the Hiroshima branch of the Sumitomo Bank. She lost consciousness after seeing a “white magnesium flash” but later awoke to the sound of a friend, Kimiko Usami, crying out for her mother, according to testimony preserved by the Hiroshima Peace Culture Foundation. The pair managed to escape the building, which had partially shielded those inside with its reinforced concrete walls, and venture into the street. There, they encountered a “whirlpool of fire” that burned everything it touched.

Akiko Takakura drawing of black rain — Akiko Takakura's drawing of the black rain that fell after the bombing of Hiroshima Drawn by Akiko Takakura / Collection of the Hiroshima Peace Memorial Museum

“It was just like a living hell,” Takakura recalled. “After a while, it began to rain. The fire and the smoke made us so thirsty and there was nothing to drink. … People opened their mouths and turned their faces toward the sky [to] try to drink the rain, but it wasn't easy to catch the rain drops in our mouths. It was a black rain with big drops.” (Kikue Shiota described the rain as “inky black and oily like coal tar.”)

The fire eventually died down, enabling Takakura and Usami to navigate through streets littered with the “reddish-brown corpses of those who were killed instantly.” Upon reaching a nearby drill ground, the young women settled in for the night with only a sheet of corrugated tin for warmth. On August 10, Takakura’s mother took her daughter, who had sustained more than 100 lacerations all over her body, home to begin the lengthy recovery process. Usami succumbed to her injuries less than a month later.

Hiroyasu Tagawa

In the spring of 1945, government-mandated evacuations led 12-year-old Hiroyasu Tagawa and his sister to move in with their aunt, who lived a short distance away from Nagasaki, while his parents relocated to a neighborhood close to their workplace in the city center.

On the morning of August 9, Tagawa heard what he thought might be a B-29 bomber flying overhead. Curious, he rushed outside to take a look. “Suddenly everything turned orange,” Tagawa told Forbes’ Jim Clash in 2018. “I quickly covered my eyes and ears and laid down on the ground. This was the position we practiced daily at school for times like this. Soon dust and debris and pieces of glass were flying everywhere. After that, silence.”

All those living at the aunt’s house survived the blast with minor injuries. But after three days passed with no news of his parents, Tagawa decided to go to the city center and search for them. There, he found piles of corpses and people similarly looking for missing family members. “Using long bamboo sticks, they were turning over one corpse after the other as they floated down the river,” he recalled. “There was an eerie silence and an overwhelming stench.”

Column of smoke over Nagasaki — A dense column of smoke rises more than 60,000 feet into the air over Nagasaki. Courtesy of the National Archives / Newsmakers

Tagawa’s mother found him first, calling out his name as he walked down the street. She and her husband had been staying in a shelter, too badly injured to make the trek back to their children. Mr. Tagawa was in particularly poor shape: A factory worker, he’d been handling dangerous chemicals when the bomb struck. Its impact sent the toxic materials flying, severely burning his feet.

Determined to aid his ailing father, Tagawa recruited several neighbors to help carry him to a temporary hospital, where doctors were forced to amputate with a carpenter’s saw. His father died three days later, leaving his grieving son uncertain of whether he’d done the right thing. “I wondered if I had done wrong by taking him over there,” Tagawa told the Japan Times’ Noriyuki Suzuki in 2018. “Had I not brought him to have the surgery, maybe he would’ve lived for a longer time. Those regrets felt like thorns in my heart.”

More tragedy was still to come: Shortly after Tagawa returned to his aunt’s town to deliver news of his father’s death, he received word that his mother—suffering from radiation poisoning—was now in critical condition. Bicycling back to her bedside, he arrived just in time to say goodbye:

My aunt said, “Your mother almost died last night, but she wanted to see you one last time. So she gave it her best to live one more day.” My mother looked at me and whispered, “Hiro-chan, my dear child, grow up fast, okay?” And with these words, she drew her last breath.

The ruins of a temple in Nagasaki after the atomic bombing Photo by Universal History Archive / Universal Images Group via Getty Images

Shoso Kawamoto

Mother tends to bomb victim — A mother tends to her injured child after the bombing of Hiroshima. Photo by Keystone / Hulton Archive / Getty Images

Eleven-year-old Shoso Kawamoto was one of some 2,000 children evacuated from Hiroshima’s city center ahead of the August 6 bombing. As he told the Chugoku Shimbun in 2013, he’d been working in a field north of the city alongside other young evacuees when he noticed a white cloud rising in the sky above Hiroshima. That night, caretakers told the group of 6- to 11-year-olds that the city center—where many of the children’s families lived—had been obliterated.

Three days later, Kawamoto’s 16-year-old sister, Tokie, arrived to pick him up. She arrived with sobering news: Their mother and younger siblings had “died at home, embracing one another,” and their father and an older sister were missing. Kawamoto never learned exactly what happened to them. (According to Elizabeth Chappell, who has interviewed Kawamoto extensively, his “samurai mother and ... farmer father” came from different backgrounds and raised their children in a strict neo-Confucian household.)

After reuniting, the siblings moved into a ruined train station, where they witnessed the plight of other orphaned children. “[W]e did not have enough food to survive,” Kawamoto later explained to author Charles Pellegrino. “We were in a constant tug-of-war over food—sometimes only one dumpling. In the end, the strong survived and the weak died one after another.” Most orphans died within months, wrote Chappell for the Conversation in 2019: Though local women tried to feed them, there simply weren’t enough rations to go around.

Tokie died of an undiagnosed illness, likely leukemia, in February 1946. Following her passing, a soy sauce factory owner took Kawamoto in, feeding and sheltering him in exchange for 12 years of labor. At the end of this period, the man rewarded his surrogate son with a house.

Tsutomu Yamaguchi

To date, the Japanese government has recognized only one survivor of both the Hiroshima and Nagasaki bombings: naval engineer Tsutomu Yamaguchi, who died in 2010 at age 93. A longtime Nagasaki resident, he’d spent the summer of 1945 on temporary assignment in Hiroshima. August 6 was set to be his last day of work before returning home to his wife and infant son.

That morning, the 29-year-old was walking to the shipyard when a “great flash in the sky” rendered him unconscious. Upon waking up, Yamaguchi told the Times’ Richard Lloyd Parry, he saw “a huge mushroom-shaped pillar of fire rising up high into the sky. It was like a tornado, although it didn't move, but it rose and spread out horizontally at the top. There was prismatic light, which was changing in a complicated rhythm, like the patterns of a kaleidoscope.”

Child and mother in Nagasaki — A child with her mother in Nagasaki on the morning after the atomic bombing Photo By Galerie Bilderwelt / Getty Images

The blast ruptured Yamaguchi’s eardrums and burned his face and forearms. But after reuniting with two co-workers—Akira Iwanaga and Kuniyoshi Sato—the trio managed to retrieve their belongings from a dormitory and start making their way to the train station. On the way, “We saw a mother with a baby on her back,” Yamaguchi recalled. “She looked as if she had lost her mind. The child on her back was dead and I don’t know if she even realized.”

Sato, who along with Iwanaga also survived both bombings, lost track of his friends on the train ride back to Nagasaki. He ended up sitting across from a young man who spent the journey clasping an awkwardly covered bundle on his lap. Finally, Sato asked what was in the package. The stranger responded, “I married a month ago, but my wife died yesterday. I want to take her home to her parents.” Beneath the cloth, he revealed, rested his beloved’s severed head.

Upon reaching Nagasaki, Yamaguchi visited a hospital to receive treatment for his burns. Deeming himself fit to work, he reported for duty the next day and was in the middle of recounting the bombing when another blinding flash of light filled the room. “I thought the mushroom cloud had followed me from Hiroshima,” he explained to the Independent’s David McNeill in 2009.

Yamaguchi was relatively unhurt, and when he rushed to check on his wife and son, he found them in a similar state. But over the next several days, he started suffering from the effects of radiation poisoning: As Evan Andrews wrote for History.com in 2015, “His hair fell out, the wounds on his arms turned gangrenous, and he began vomiting incessantly.”

With time, Yamaguchi recovered and went on to live a normal life. He was, in fact, so healthy that he avoided speaking out about his experiences for fear of being “unfair to people who were really sick,” as his daughter Toshiko told the Independent. In total, an estimated 165 people survived both bombings. Yamaguchi remains the only one to receive official recognition.

Nine Eyewitness Accounts of the Bombings of Hiroshima and Nagasaki