... On 6 August and 9 August 1945, the first two atomic bombs to be used for military purposes were dropped on Hiroshima and Nagasaki respectively. One hundred thousand people were killed, 6 square miles or over 50 percent of the built-up areas of the two cities were destroyed. The first and crucial question about the atomic bomb thus was answered practically and conclusively; atomic energy had been mastered for military purposes and the overwhelming scale of its possibilities had been demonstrated. A detailed examination of the physical, economic, morale effects of the atomic bombs occupied the attention of a major portion of the Survey's staff in Japan in order to arrive at a more precise definition of the present capabilities and limitations of this radically new weapon of destruction.

Eyewitness accounts of the explosion all describe similar pictures. The bombs exploded with a tremendous flash of blue-white light, like a giant magnesium flare. The flash was of short duration and accompanied by intense glare and heat. It was followed by a tremendous pressure wave and the rumbling sound of the explosion. This sound is not clearly recollected by those who survived near the center of the explosion, although it was clearly heard by others as much as fifteen miles away. A huge snow-white cloud shot rapidly into the sky and the scene on the ground was obscured first by a bluish haze and then by a purple-brown cloud of dust and smoke.

Such eyewitness accounts reveal the sequence of events. At the time of the explosion, energy was given off in the forms of light, heat, radiation, and pressure. The complete band of radiations, from X- and gamma-rays, through ultraviolet and light rays to the radiant heat of infra-red rays, traveled with the speed of light. The shock wave created by the enormous pressures built up almost instantaneously at the point of explosion but moved out more slowly, that is at about the speed of sound. The superheated gases constituting the original fire ball expanded outward and upward at a slower rate.

The light and radiant heat rays accompanying the flash traveled in a straight line and any opaque object, even a single leaf of a vine, shielded objects lying behind it. The duration of the flash was only a fraction of a second, but it was sufficiently intense to cause third degree burns to exposed human skin up to a distance of a mile. Clothing ignited, though it could be quickly beaten out, telephone poles charred, thatch-roofed houses caught fire. Black or other dark-colored surfaces of combustible material absorbed the heat and immediately charred or burst into flames; white or light-colored surfaces reflected a substantial portion of the rays and were not consumed. The heavy black clay tiles which are an almost universal feature of the roofs of Japanese houses bubbled at distances up to a mile. Test of samples of this tile by the National Bureau of Standards in Washington indicates that temperatures in excess of 1.800 degrees C. must have been generated in the surface of the tile to produce such an effect. The surfaces of granite blocks exposed to the flash scarred and spalled at distances up to almost a mile. In the immediate area of ground zero (the point on the ground immediately below the explosion), the heat charred corpses beyond recognition.

Penetrating rays such as gamma-rays exposed X-ray films stored in the basement of a concrete hospital almost a mile from ground zero. Symptoms of their effect on human beings close to the center of the explosion, who survived other effects thereof, were generally delayed for two or three days. The bone marrow and as a result the process of blood formation were affected. The white corpuscle count went down and the human processes of resisting infection were destroyed. Death generally followed shortly thereafter.

The majority of radiation cases who were at greater distances did not show severe symptoms until 1 to 4 weeks after the explosion. The first symptoms were loss of appetite, lassitude and general discomfort. Within 12 to 48 hours, fever became evident in many cases, going as high as 104 to 105 degrees F., which in fatal cases continued until death. If the fever subsided, the patient usually showed a rapid disappearance of other symptoms and soon regained his feeling of good health. Other symptoms were loss of white blood corpuscles, loss of hair, and decrease in sperm count.

Even though rays of this nature have great powers of penetration, intervening substances filter out portions of them. As the weight of the intervening material increases the percentage of the rays penetrating goes down. It appears that a few feet of concrete, or a somewhat greater thickness of earth, furnished sufficient protection to humans, even those close to ground zero, to prevent serious after effects from radiation.

The blast wave which followed the flash was of sufficient force to press in the roofs of reinforced-concrete structures and to flatten completely all less sturdy structures. Due to the height of the explosion, the peak pressure of the wave at ground zero was no higher than that produced by a near-miss of a high-explosive bomb, and decreased at greater distances from ground zero. Reflection and shielding by intervening hills and structures produced some unevenness in the pattern. The blast wave, however, was of far greater extent and duration than that of a high-explosive bomb and most reinforced-concrete structures suffered structural damage or collapse up to 700 feet at Hiroshima and 2,000 feet at Nagasaki. Brick buildings were flattened up to 7,300 feet at Hiroshima and 8,500 feet at Nagasaki. Typical Japanese houses of wood construction suffered total collapse up to approximately 7,300 feet at Hiroshima and 8,200 feet at Nagasaki. Beyond these distances structures received less serious damage to roofs, wall partitions, and the like. Glass windows were blown out at distances up to 5 miles. The blast wave, being of longer duration than that caused by high-explosive detonations, was accompanied by more flying debris. Window frames, doors, and partitions which would have been shaken down by a near-miss of a high-explosive bomb were hurled at high velocity through those buildings which did not collapse. Machine tools and most other production equipment in industrial plants were not directly damaged by the blast wave, but were damaged by collapsing buildings or ensuing general fires....

The Survey has estimated that the damage and casualties caused at Hiroshima by the one atomic bomb dropped from a single plane would have required 220 B-29s carrying 1,200 tons of incendiary bombs, 400 tons of high-explosive bombs, and 500 tons of antipersonnel fragmentation bombs, if conventional weapons, rather than an atomic bomb, had been used. One hundred and twenty-five B-29s carrying 1,200 tons of bombs would have been required to approximate the damage and casualties at Nagasaki. This estimate presupposed bombing under conditions similar to those existing when the atomic bombs were dropped and bombing accuracy equal to the average attained by the Twentieth Air Force during the last 3 months of the war.

As might be expected, the primary reaction of the populace to the bomb was fear, uncontrolled terror, strengthened by the sheer horror of the destruction and suffering witnessed and experienced by the survivors. Prior to the dropping of the atomic bombs, the people of the two cities had fewer misgivings about the war than people in other cities and their morale held up after it better than might have been expected. Twenty-nine percent of the survivors interrogated indicated that after the atomic bomb was dropped they were convinced that victory for Japan was impossible. Twenty-four percent stated that because of the bomb they felt personally unable to carry on with the war. Some 4,0 percent testified to various degrees of defeatism. A greater number (24 percent) expressed themselves as being impressed with the power and scientific skill which underlay the discovery and production of the atomic bomb than expressed anger at its use (20 percent). In many instances, the reaction was one of resignation....

The following is the account of a girl who was attending junior college in Hiroshima when the atomic bomb exploded.

ATSUKO TSUJIOKA: A RECOLLECTION OF HIROSHIMA

Ah, that instant! I felt as though I had been struck on the back with something like a big hammer, and thrown into boiling oil. For some time I was unconscious. When I abruptly came to again, everything around me was smothered in black smoke; it was all like a dream or something that didn't make sense. My chest hurt, I could barely breathe, and I thought 'This is the end!' I pressed my chest tightly and lay face down on the ground, and ever so many times I called for help....

Through a darkness like the bottom of Hell I could hear the voices of the other students calling for their mothers. I could barely sense the fact that the students seemed to be running away from that place. I immediately got up, and without any definite idea of escaping I just frantically ran in the direction they were all taking. As we came close to Tsurumi Bridge a red hot electric wire wrapped itself around both my ankles. I don't know how but I managed to pull it off, and as though I were moving in a dream I reached the end of the bridge. By this time everything had long since changed to white smoke. The place where I had been working was Tanaka-cho, a little more than 600 yards from the center of the explosion. Although I should have been at a place straight in from Tsurumi Bridge, I seem to have been blown a good way to the north, and I felt as though the directions were all changed around.

At the base of the bridge, inside a big cistern that had been dug out there, was a mother weeping and holding above her head a naked baby that was burned bright red all over its body, and another mother was crying and sobbing as she gave her burned breast to her baby. In the cistern the students stood with only their heads above the water and their two hands, which they clasped as they imploringly cried and screamed, calling their parents. But every single person who passed was wounded, all of them, and there was no one to turn to for help. The singed hair on people's heads was frizzled up and whitish, and covered with dust-from their appearance you couldn't believe that they were human creatures of this world. Looking at these people made me think suddenly 'It can't be possible that I-' I looked at my two hands and found them covered with blood, and from my arms something that looked like rags was hanging and inside I could see the healthy-looking flesh with its mingled colors of white, red and black. Shocked, I put my hand into my mompei [slacks] pocket to get out my handkerchief, but there was no handkerchief, nor pocket either. And my mompei were also burned off below my hips. I could feel my face gradually swelling up, but there was nothing I could do about it, and when some of my friends suggested that we try to return to our homes in the suburbs, I set out with them. As we walked along, fires were blazing high on both sides of us, and my back was painfully hot. From inside the wreckage of the houses we could hear screaming voices calling "Help!" and then the flames would swallow up everything. A child of about six, all covered with blood, holding a kitchen pot in his arms, was facing a burning house, stamping his feet and screaming something. . . .

Luckily there were some kind soldiers from a medical unit there, and they carried me up the hill to a place where I could lie down. There they gave me first aid treatment right away. It seemed that I had received a terrific blow on the back of my head, and there were fragments of roof tile left there. They pulled these out and bandaged the wound for me....

My father and four or five of our neighbors were searching around for me day after day and finally on the evening of the third day they discovered me in one corner of the barracks at the foot of Futaba Hill. On my blouse there was sewn a name-tag that my father had written for me; the letters had been burned out just as though that part of the cloth had been eaten away by moths, and it was by this that they were able to find me.

"Atchan. This is Father."

When he said that, I was so happy that I couldn't say a word-I could only nod my head. My swollen eyes wouldn't open, so I couldn't see my father's face. This is how I was rescued.

Even now the scars of those wounds remain over my whole body. On my head, my face, my arms, my legs and my chest. As I stroke these blackish-red raised scars on my arms, and every time I look in a mirror at this face of mine which is not like my face, and think that never again will I be able to see my former face and that I have to live my life forever in this condition, it becomes too sad to bear. At the time I lost hope for the future. But with human beings, it isn't only a beautiful outward appearance that is good. True beauty, worthy of a human being, takes away an ugly appearance and makes it into a splendid one....

It is my hope that in the future such a tragic event as this will never make a second appearance in this world. And I want things to work out so that atomic energy will be the power which will give birth to a peaceful world. I believe there is no necessity for mankind to experience directly such suffering.