The US wanted Japan, which was an enemy in the ongoing Second World War, to surrender. But it is also said that the United States wanted to test its new weapon and see its effects. The two atomic bombs were also a demonstration of the United States’ nuclear weapons capability to the Soviet Union, which was an ally at the time but soon became an enemy in the ensuing Cold War.

Hiroshima

By the end of World War II, American air raids had destroyed most Japanese cities. Hiroshima was one of the cities that remained undamaged. The city was an important port with many Japanese soldiers, military areas and military factories that had not yet been subjected to American attacks. Most adult men were at the front, so the population consisted mainly of women, the elderly, refugees and children aged 12 and above who had been mobilised to work for the armed forces. There were also slave labourers from Korea.

August 6, 1945

Early in the morning on 6 August 1945, the Enola Gay aircraft left the American-occupied Japanese island of Tinian. The Enola Gay was one of seven American aircraft flying to Hiroshima, but it was the only one carrying an atomic bomb. The bomb was over three metres long, 75 centimetres in diameter and weighed nearly 4 tonnes. It contained 60 kg of uranium-235 and was named Little Boy.

At 7 a.m., Japanese radar showed that an American aircraft was heading for Hiroshima, and warnings were broadcast on the radio. Shortly afterwards, a civilian aircraft was spotted, but there were no signs of a bomber, so the residents of Hiroshima returned to their normal morning routines. When radio stations issued another warning at 8 o’clock about incoming bombers, many ignored it as yet another false alarm.

At 8:15 a.m., Little Boy was dropped from the aircraft. It took 45 seconds for the bomb to detonate about 580 metres above Hiroshima. It created an explosion with a blast force of approximately 15 kilotons of TNT. The temperature at the moment of explosion was so high that the surrounding air formed a huge fireball measuring over 250 metres. Survivors describe the intense light that flashed and blinded them several times more intensely than the sun, closely followed by intense heat.

Catastrophic consequences

The shock wave shattered windows more than 15 kilometres from the site of the explosion and was felt up to 60 kilometres away. Within a radius of 1.6 kilometres, the destruction was total. The heat from the explosion ignited hundreds of fires, which together formed a massive firestorm. Within a radius of about ten kilometres, the fire destroyed everything it came into contact with. A small part of the settlement survived, mainly because Hiroshima is an earthquake-prone area and many important buildings had therefore been built extra strong to withstand severe earthquakes.

About half an hour after the explosion, it began to rain heavily. The ‘black rain’ was full of dirt, dust, soot and radioactive particles that had been sucked into the air by the explosion and fires. Due to the fallout, areas far from the site of the explosion were also contaminated.

The soldiers on the Enola Gay looked down over Hiroshima after dropping the bomb from the aircraft. The city had disappeared from view and all that could be seen was a huge black cloud of soot and intense flames. The co-pilot, Captain Richard Lewis, commented: ‘Oh my God, what have we done?’ But the crew returned to their camp and were welcomed as heroes.

Confusion in the military

The confusion at Japan’s military headquarters was total. Chaotic reports came in about ‘strange clouds’, ‘huge explosions’ and ‘terrible flashes of light’, and when attempts were made to contact the military station in Hiroshima, there was total silence. Military headquarters knew that no major enemy attack had taken place, as this would have been visible on the radar screens. Nor were there any large stocks of explosives in Hiroshima. A pilot was sent out to investigate what had happened and finally concluded that something terrible had occurred. The Japanese military leadership was shocked: no one had believed that the United States had come so far in the development of nuclear weapons.

In total, up to 140,000 people in Hiroshima had died by the end of World War II as a result of the immediate and long-term damage of the bomb.

Nagasaki

The bombing of Nagasaki has always been overshadowed by Hiroshima. The bombing of Hiroshima on 6 August 1945 went exactly according to the plans of the American military leadership. However, the United States had decided to drop two atomic bombs on Japan, a uranium bomb and a plutonium bomb, a few days apart. The second bomb was to be dropped on 11 August on the Japanese city of Kokura, with Nagasaki as the alternative target. But the American military leadership saw that bad weather was on its way and decided to drop the second atomic bomb, called Fat Man, on 9 August.

Low Fuel Supply

While the crew of the Enola Gay was still being celebrated for their success after Hiroshima, the crew on the second mission ran into problem after problem. A typhoon threatened the island of Iwo Jima, which was to be the starting point, so they had to move the starting point to the island of Yakushima. When the atomic bomb was to be loaded onto the plane Bock’s Car, the crew discovered that only one of the fuel pumps on board was working.

This limited the aircraft’s fuel supply, and the crew realised that they might not be able to land safely after completing the mission before running out of fuel. But there was no time to lose; if the Japanese were to be convinced that America’s second atomic bomb was not just an empty threat, they had to act quickly.

Fat Man was built with a core of plutonium surrounded by high-explosive material which, when ignited, created a powerful nuclear reaction. Fat Man weighed over 4.5 tonnes, was 3.25 metres high and had a diameter of over one and a half metres.

When the bomber reached Kokura, where the bomb was to be dropped, the city was covered in thick fog. The crew had no choice but to head for alternative target number two, Nagasaki. Nagasaki was chosen as the target mainly because of Mitsubishi’s two large steel and weapons factories located there.

Here too, the cloud cover was thick, but the plane was running out of fuel and the decision was made to drop the bomb. At the last second, a gap opened up in the cloud cover. At 11:02 a.m., Fat Man fell on Nagasaki.

Fat Man exploded 43 seconds later, 469 metres above the ground. The bomb detonated with a force equivalent to 21 kilotons of TNT and missed its target by almost 3 kilometres. The explosion in Nagasaki did not create as massive a firestorm as in Hiroshima, but due to the bomb’s explosive power and the fact that it was dropped over a valley, the explosion itself was still more destructive to the immediate surroundings.

An obliterated city

The destruction in the rest of Nagasaki was somewhat limited by the city’s many mountains and valleys.

However, this did not mean that the city was spared in any way. Three days after the atomic bomb was dropped on the city, an aerial photograph shows Nagasaki as a flat, desolate landscape, a city wiped out.

The area within a kilometre radius of the epicentre was completely destroyed by the heat and shock wave created by the explosion. Buildings, plants and living creatures were pulverised. Within a further kilometre radius, nearly 80 per cent of all buildings collapsed.

Unlike the more modern Hiroshima, Nagasaki consisted largely of older wooden houses and generally weaker structures. Windows and doors were shattered as far as 15 kilometres from the bomb site.

In total, over 90,000 people were killed in Nagasaki, and many of those who survived the bombing suffered from cancer and other genetic diseases for years after the bombing.

No tributes

One minute after the bomb was dropped, the crew of the crew in the American plane Bock’s Car and the accompanying reconnaissance plane saw a huge fireball. The pilots had to tilt the plane sharply backwards to avoid being hit. Five closely following shock waves shook the plane and a radioactive cloud flowed towards them. The plane was unable to continue to the island of Tinian and was forced to make an emergency landing on the island of Okinawa. After a dramatic landing, with barely 25 litres of fuel left in the tank, the weary crew was met with emptiness. No one was there to welcome them and no ceremony awaited them.

Unexpected criticism

Before the bombs were dropped on Hiroshima and Nagasaki, protests came from an unexpected source. Physicist Leo Szilard, who had previously initiated the creation of the atomic bomb, started a petition among scientists against the use of the atomic bomb against Japan. 88 signatures were collected. However, Szilard’s nomination was classified as secret and was not made public until the 1960s.

Sources and more information

Hiroshima, Atomicarchive.com
Nagasaki, Atomicarchive.com
The Atomic Bombing of Hiroshima and Nagasaki, August 1945, National Archives
Atomic Bombings of Hiroshima and Nagasaki, Britannica
Unexpected Opposition, Atomicarchive.com