U.S. Strategic Bombing Survey: The Effects of the Atomic Bombings of Hiroshima and Nagasaki, 19 June, 1946

I will only note a few of the conclusions of this slightly length report.

(Hiroshima) “Most of the industrial workers had already reported to work, but many workers were enroute and nearly all the school children and some industrial employees were at work in the open on the program of building removal to provide firebreaks and disperse valuables to the country.”

”The bomb exploded slightly northwest of the center of the city. Because of this accuracy and the flat terrain and circular shape of the city, Hiroshima was uniformly and extensively devastated. Practially the entire densely or moderately built-up portion of the city was leveled by blast and swept by fire. A 'fire-storm', a phenomenon which has occurred infrequently in other conflagrations, developed in Hiroshima; fires springing up almost simultaneously over the wide flat area around the center of the city drew in air from all directions.”

”Seventy to eighty thousand people were killed, or missing and presumed dead, and an equal number were injured.”

”...the whole city suffered damage such as would have resulted from directly its everywhere by ordinary bombs.”

(Nagasaki) “...no fire storm arose, and the uneven terrain of the city confined the maximum intensity of damage to the valley over which the bomb exploded...between 35,000 and 40,000 were killed, and about the same number injured.”

The report talks about the building construction in the cities, how many of them were wood (and easily burned), and also how even though some were concrete structures, their building quality of the concrete was poor and this led to building collapses that might not have happened if the concrete and construction were of good quality.

The report says about 7% of the residential units had been torn down to make firebreaks.

Hiroshima was the headquarters of the Second Army and of the Chugoku Regional Army. “It was one of the most important military command stations in Japan, the site of one of the largest military supply depots, and the foremost military shipping point for both troops and supplies.”

Around 30% of the population was killed and another 30% injured. This included people across all lines, so, for example, over 90% of the doctors were casualties. “Out of 1,780 nurses, 1,654 were killed or injured.” 42 of 45 civilian hospitals were rendered unusable.

It took about 30 hours before any form of rescue parties were observed. In Hiroshima, there were only 16 pieces of fire-fighting equipment to fight the conflagration started by the bomb.

Despite all the death and destruction, the city was not totally destroyed. Some railroad service was available as early as two days after the bombing. Electric power was partially restored the next day. The telephone service was knocked out until about the 15th of August.

”Industry in the center of the city was effectively wiped out. Though small workshops numbered several thousand, they represented only one-fourth of the ttotal industrial production of Hiroshima, since many of them had only one or two workers. The bulk of the city's output came from large plants located on the outskirts of the city.”

”The official Japanese figures summed up the building destruction at 62,000 out of a total of 90,000 buildings in the urban area, or 69%. An additional 6,000 or 6.6% were severely damaged, and most of the others showed glass breakage or disturbance of roof tile.”

Nagasaki's commercial importance had apparently been on the decline due its location and inadequate roads.

In Nagasaki, as in Hiroshima, medical personnel and facilities were hard-hit by the bomb. The Medical College was located 3,000 feet from where the bomb exploded. 600 of 850 students were killed and most of the rest injured. Of 20 faculty members, 12 were killed, another 4 injured.

Shipping was not really affected by the bomb, but trolley service was halted due to damage to street cars and the electrical lines. Also, 112 of 1115 employees of the street car company were killed.

Because parts of the city were protected by hills, destruction of residences was less than in Hiroshima. 27.2% were completely destroyed. Several industrial plants were badly damaged. Despite the destruction, plant production could have been restored if raw materials had been available, although it would have taken a year to a year and a half to do so. Repairs to the docks could have had them working at 80% efficiency within four months.

”The Survey believes the dead at Hiroshima to have been between 70,000 and 80,000, with an equal number injred; at Nagasaki over 35,000 dead and somewhat more than that injured seem the most plausible estimate.”

”At the time of impact, however, the causes of death and injury were flash burns, secondary effects of blast and falling debris, and burns from blazing buildings. ...burns caused at least 50% of the initial casualties.”

”Of those who died later, an increasing proportion succumbed to radiation effects.”

The report says that probably 15 to 20% of the deaths in the two cities was due to radiation.

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