On this day · 9 August

1945

On This Day: 9 August 1945 – Atomic Bomb Hits Nagasaki

Political event

The United States dropped an atomic bomb on Nagasaki on 9 August 1945, killing tens of thousands of people and leaving survivors with lifelong injuries and radiation-related illness.

On 9 August 1945, the United States dropped an atomic bomb on the Japanese city of Nagasaki.

At 11.02am, the plutonium weapon exploded above the Urakami Valley, releasing a blast, fire and radiation on a scale the city could scarcely comprehend.

Tens of thousands of people were killed immediately or during the months that followed. Estimates differ, but approximately 70,000 to 74,000 people are believed to have died by the end of 1945.

The attack came only three days after the atomic bombing of Hiroshima. Hiroshima and Nagasaki remain the only cities against which nuclear weapons have been used in war.

Three days after Hiroshima

By August 1945, the Second World War had ended in Europe but continued in Asia and the Pacific.

Japan’s cities had already suffered devastating conventional bombing, its navy had been largely destroyed and its supply system was collapsing. Nevertheless, its government had not accepted the Allied demand for surrender contained in the Potsdam Declaration.

On 6 August, the American B-29 Enola Gay dropped a uranium atomic bomb on Hiroshima. Much of the city was destroyed and tens of thousands of people died.

On 8 August, the Soviet Union declared war on Japan. Soviet forces then launched a huge offensive against the Japanese-controlled territory of Manchuria.

Against this rapidly changing background, the United States proceeded with a second atomic-bomb mission.

Kokura was the primary target

The B-29 bomber Bockscar, piloted by Major Charles Sweeney, took off from the Pacific island of Tinian carrying the weapon known as “Fat Man”.

Unlike the uranium device used over Hiroshima, Fat Man was an implosion-type weapon containing plutonium. Its explosive force was equivalent to approximately 21,000 tons of TNT.

The mission’s primary target was not Nagasaki but the city of Kokura, which contained a large military arsenal.

Cloud, haze and smoke obscured the aiming point. After several approaches, and with fuel becoming dangerously limited, the crew abandoned Kokura and flew towards the secondary target.

Nagasaki was also partly covered by cloud. A break appeared shortly before the aircraft would have needed to abandon the bombing, allowing the bombardier to make a visual approach.

11.02am over the Urakami Valley

The bomb was released and detonated at 11.02am, around 500 metres above the city’s Urakami district.

The explosion created an intense flash and fireball, followed by a crushing blast wave. People close to the hypocentre were killed instantly. Buildings collapsed, fires spread and fragments of glass and timber became deadly projectiles.

Temperatures near the centre of the explosion caused catastrophic burns. People farther away were injured by collapsing structures and flying debris, while many who initially appeared to have survived had received dangerous doses of radiation.

The bomb missed its intended aiming point by several kilometres. Nagasaki’s surrounding hills restricted some of the blast’s reach, but the Urakami Valley was devastated.

A city of civilians, workers and worshippers

Nagasaki was an industrial and naval centre containing Mitsubishi arms factories, shipyards and other facilities supporting Japan’s war effort.

It was also a living city filled with homes, schools, hospitals, places of worship and people going about their daily lives.

The Urakami district was home to a large Roman Catholic community. Urakami Cathedral, then one of the largest churches in Asia, stood close to the hypocentre and was destroyed. Worshippers and clergy were among those killed.

The dead included Japanese civilians, factory workers, children, medical staff, Korean forced labourers and prisoners of war. Entire families disappeared and neighbourhoods were reduced to ruins within seconds.

Hospitals overwhelmed

The survivors encountered an almost complete breakdown of medical care precisely when it was most desperately needed.

Doctors and nurses had been killed or injured, hospitals were damaged and medical supplies were buried or burned. Roads were blocked and communications failed.

People suffered severe burns, blindness, fractures and wounds contaminated by debris. In the days that followed, survivors who had escaped visible injury began developing fever, vomiting, bleeding, hair loss and profound weakness.

The nature of acute radiation sickness was not widely understood. Medical workers had few means to treat it, while continuing radiation exposure presented dangers that could not be seen or felt.

Deaths continued for weeks and months. Later studies also found increased risks of leukaemia and other cancers among those exposed.

The hibakusha

Survivors of the atomic bombings became known in Japan as hibakusha—people affected by the explosion.

They carried burns, disabilities, grief and radiation-related illness long after the war ended. Many also faced discrimination in employment and marriage because of mistaken fears that radiation sickness was contagious or would inevitably be inherited by their children.

Over subsequent decades, survivors documented what they had witnessed and campaigned for the abolition of nuclear weapons. Their testimony ensured that the bombings were remembered not merely through military calculations and political decisions, but through individual lives.

Japan moves towards surrender

News of Nagasaki reached Japan’s leaders as they were already confronting the destruction of Hiroshima and the Soviet entry into the war.

The relative importance of the atomic bombings, the Soviet offensive, the Allied blockade and Japan’s deteriorating military position in producing surrender has remained the subject of historical debate.

What is clear is that the combined crisis forced an immediate decision. Japan’s Supreme War Council and cabinet remained divided over the conditions upon which surrender might be accepted.

Emperor Hirohito intervened in favour of accepting the Potsdam terms, subject to the position of the imperial institution. On 15 August, his recorded broadcast informed the Japanese people that the country would accept surrender.

The formal surrender was signed aboard USS Missouri on 2 September 1945, bringing the Second World War to its final conclusion.

A decision still debated

Supporters of the bombing argued that it accelerated Japan’s surrender and avoided an invasion of the home islands that could have killed enormous numbers of Allied service personnel and Japanese people.

Critics have questioned whether Japan was already close to defeat, whether surrender could have been secured through different terms, whether more time should have been allowed after Hiroshima and the Soviet declaration of war, or whether the weapon could have been demonstrated away from a populated city.

Those arguments remain part of the historical and moral debate surrounding the end of the Pacific War.

No analysis, however, can erase the immediate reality in Nagasaki: a single weapon destroyed communities and killed tens of thousands of people, most of them civilians.

Remembering Nagasaki

Each year, Nagasaki observes a moment of silence at 11.02am on 9 August. The Peace Park and Atomic Bomb Museum preserve the evidence of the attack and the testimony of its survivors.

The city’s remembrance is inseparable from its appeal for peace and nuclear disarmament.

As the number of surviving hibakusha diminishes, preserving their accounts has become increasingly urgent. They describe not an abstract weapon but a city burning, desperate searches for family members and illnesses that emerged after the visible destruction had ended.

Nagasaki rebuilt, but 9 August 1945 remains an enduring warning of what nuclear warfare means for human beings.