The Pacific Theater of World War II was fought mainly in the territories of the Empire of Japan.

At the peak of its power, the empire comprised a large portion of Southeast Asia and eastern China and the islands of Oceania and the Aleutian Islands in North America.

The Allied forces’ planned invasion of Japan included two atomic bombs assembled in the Marianas and loaded into B-29 bombers.

Scientists had warned about the excessive destruction that such bombs could bring upon, but the plan was considered necessary to end the war immediately.

After the bombing, the Japanese government announced its willingness to surrender.

The primary targets of the bombing were two Japanese cities, the first of which was Hiroshima in Honshu Island, an industrial hub and a military activity center in the country.

Before the bombing, the city had a civilian population of almost 300,000 and some 43,000 soldiers.

On August 6, 1945, at approximately 8:15 a.m. local time, most of Hiroshima was obliterated by an atomic bomb nicknamed “Little Boy” dropped from 31,000 feet above the city.

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10 /10 Brighter Than A Thousand Suns

When the atomic bomb detonated at 1,900 feet altitude directly above a military training ground, a massive blast of noise accompanied by a burst of light that some said was brighter than a thousand suns swept the city with the kind of force that only a handful of people had seen before.

A fireball quickly transformed into a giant mushroom cloud, leaving behind a devastating flood of heat and blast power. Everything near the explosion was turned to ash.

An area of a 4.4 square miles radius became nothing but a big pile of rubble within seconds.

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9 /10 A Flat City

The city of Hiroshima was essentially a flat stretch of land divided by the channel outlets of the Ota River into six islands projecting the Hiroshima Bay to the south.

It is only slightly above sea level except in the northwest and northeast corners, where some hills rise to about 700 feet.

The city has a minor elevation in the eastern part, rising approximately 220 feet high, but it is reasonably long at about half a mile from one end to another.

If not for this hill, Hiroshima would have been entirely exposed by the explosion 76 years ago.

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8 /10 Radiation Poisoning

Some 70,000 people were killed by the immediate blast, whereas anywhere between 70,000 and 80,000 were injured.

Tens of thousands more survived the initial explosion but ultimately succumbed to radiation poisoning.

Damage to artificial structures was mainly attributed to two properties of the atomic bomb: pressure wave, which emanated from the center of the blast, and fires caused by both the heat of the explosion and the destroyed buildings containing flammable materials and equipment to generate secondary fire.

The initial blast alone was estimated to be the equivalent of 20 kilotons of TNT.

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7 /10 Susceptible To Fire Damage

The scale of devastation in Hiroshima was partly due to the layout of the city. Only about 7 square miles of the area had been built up. There was no clear marking or separation of residential, commercial, and industrial zones.

At the center of the city, several buildings were constructed using reinforced concrete, but they had lighter structures too.

Most importantly, a dense neighborhood filled with wooden houses and workshops was located outside the center; even many industrial buildings were of wooden construction.

Hiroshima, at the time of the bombing, was susceptible to fire damage.

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6 /10 Concentrated Population

Hiroshima held a position of importance in the Japanese military. The 2nd Army Headquarters, the commanding officer for the defense of the entire southern part of the country, stood in the city.

The military used it as an important communication center, storage point, and assembly area. All in all, it was indispensable for the Imperial Japanese Army.

About 75% of the population is centered in the built-up area. One Japanese report suggested that the people of Hiroshima had probably for more than a thousand times seen the troops leaving from the harbor since World War II began.

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5 /10 Reinforced Concrete

Nearly everything within a mile radius of the explosion was destroyed. About 50 buildings, despite being within close distance to the center of the blast, did not collapse.

These buildings were built using reinforced concrete designed to withstand earthquake shock in Japan, resulting in constructions more structurally sound than usual standards in the United States.

Although the frameworks were not entirely damaged, the interiors told a different story. All the windows, doors, and sashes vanished.

However, most buildings in Hiroshima by August 1945 were constructed with much lower requirements in mind.

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4 /10 Inaccurate Population Count

Due to the inaccurate population count before the bombing, it became difficult to determine casualties. Early in the war, the peak population in Hiroshima reached 380,000 people.

A systematic evacuation mandated by the Japanese government eventually reduced the population to about 255,000 at the time of the bombing.

Bear in mind the number was based on registered residents only, excluding any additional workforce brought into the city.

The actual headcount was more or less the equivalent of the residents of Dallas, Texas, or Providence, Rhode Island, in August 1945.

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3 /10 Casualties Estimate

At the very least, Little Boy killed 66,000 people and injured 69,000 others with the initial blast and heat alone.

The vast majority of residents within 6,600 feet from the hypocenter (who were not instantly killed) died from complications compounded by Acute Radiation Syndrome (ARS) within at most 30 days after the attack.

Approximately 4,000 feet from the blast, roof tiles either melted or bubbled by flash heat. A circular area of about 6,000 feet radius sustained heavy fire damage.

The atomic bomb also destroyed 60,000 buildings or about two-thirds of all artificial structures in Hiroshima.

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2 /10 Rapid Restoration

Transportation and utilities sustained heavy damage, too, of course. Japan was able to restore some services quite rapidly for the depleted population of Hiroshima to use.

In most areas largely unaffected by the blast power and flash heat, electric power became available again just one day after the bombing.

While the water reservoir was not severely damaged, water pipes running to tens of thousands of buildings burst beyond repair despite being only about two miles from the hypocenter.

Telephone service was not restored until August 15. Damage to roads and railroad tracks was surprisingly minor.

National Museum of Health and Medicine

1 /10 Mechanical Injuries And Burns

Because many of the victims suffered from more than one effect of the atomic bomb explosion, it is impossible to assign an exact percentage for every type of injury.

One thing is sure: a good number of the total casualties resulted from mechanical damages and burns.

Mechanical injuries included contusions, fractures, and abrasions in addition to those caused by crumbling structures.

American radiologist Colonel Stafford L. Warren estimated that only about 7% of deaths in the wake of the Hiroshima bombing resulted from radiation disease.

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