Photographs of Hiroshima before and after the atomic bombing, 1945

 

At the time of the bombing, Hiroshima was a city of both industrial and military importance. Several military units were located nearby, the most important of which was the headquarters of Field Marshal Shunroku Hata's Second General Army, which commanded the defense of all of southern Japan, and was located at Hiroshima Castle. Hata's command consisted of approximately 400,000 men, most of whom were on Kyushu, where there were real fears of an Allied invasion.

Hiroshima was a small supply and logistics base for the Japanese military, but it also contained large stores of military supplies. The city was also a communications center, a major port for shipping, and a gathering area for troops.

It was a hive of war industry, producing parts for planes and boats, bombs, rifles, and handguns; Children were shown how to make and throw gasoline bombs and people in wheelchairs and bedridden people were assembling booby traps to be planted in Kyushu's beaches.

A new slogan appeared on the walls of Hiroshima: “Forget Yourself! Everything for your country!”. It was also the second largest city in Japan after Kyoto that was still untouched by air raids.

There were many reinforced concrete buildings and light structures in the city center. Outside the center, the area was filled with a dense collection of small wood-working workshops nestled among Japanese houses.

Some large industrial plants are located on the outskirts of the city. Houses were constructed of wood with tile roofs, and many industrial buildings were also built around wood frames. The city as a whole was highly vulnerable to fire damage.

The population of Hiroshima reached a peak of more than 381,000 before the war, but before the atomic bombing, the population had steadily declined due to the systematic evacuation ordered by the Japanese government. At the time of the attack, the population was approximately 340,000–350,000.

Residents wondered why Hiroshima was saved from destruction by firebombing. Some speculated that the city was to be saved for the American occupation headquarters, others thought that perhaps their relatives in Hawaii and California had petitioned the US government to avoid the bombing of Hiroshima.

More realistically, city officials, starting in 1944, ordered the demolition of buildings to create long, straight firebreaks. The firebreak continued and extended until the morning of August 6, 1945.

On August 6, the US dropped a uranium gun-type (Little Boy) bomb on Hiroshima, and US President Harry S. Truman called for Japan's surrender, and warned that "the wind is expected to rain destruction the likes of which has never been seen on this earth".

At 8:15 a.m. on Monday, August 6, 1945, the American B-29 bomber Enola Gay, flown by Colonel Paul Tibbetts, dropped the "Little Boy" nuclear weapon on Hiroshima, killing about 70,000 people. Which included 20,000 Japanese fighters and 2,000 Korean slave laborers.

By the end of the year, the total death toll from injuries and radiation reached 90,000–166,000. The population before the bombing was approximately 340,000 to 350,000. About 70% of the city's buildings were destroyed, and another 7% were seriously damaged.