On August 6th, 1945, the US made a significant step toward securing peace in the war with the Japanese, yet took an even larger leap into making the world a little less secure. That day, at 8:15am local time, the B-29 commonly known as the Enola Gay released "Little Boy". Weighing 9,700 pounds, it had the explosive power of 20,000 tons of TNT.
The choice of city was not random. Four cities were selected as potential targets: Hiroshima, Kokura, Nagasaki, and Niigata. The committee set up to select the target decided that the first bomb must be dropped on a city that was relatively untouched by previous bombing runs on the country. Thus Tokyo, the much bombed capital, was off the list. The reason was simple: if the city was nearly pristine, the impact of the weapon would be more measurable, and thus the importance of the weapon immediately seen by our enemies and the allies alike.
There was another reason for selecting Hiroshima: it was the headquarters for both the Japanese 5th Division and the 2nd Army. The port was also an important communications center. However, it was known that the explosive power of the bomb was too vast to be limited to targeting military bases. Civilians, even those not involved in the war effort, were expected to perish.
Scientists had believed that the civilians would hide in bomb shelters and thus expected the loss of life to be much lower than the 80,000 or more people who died instantly. However, the single B-29 did not cause the people to fear a bombing, so most carried on with their activities. Because the uranium-235 bomb had not been tested, the US decided not to tell the Japanese about the impending bombing, in case it malfunctioned.
As the weather was reported to be clear over the primary choice of Hiroshima, the go-ahead was given to target the T-shaped Aioi Bridget in the middle of the city. Due to crosswind, the bomb detonated 1,900 feet above the Shima Surgical Clinic, some 800 feet from the targeted bridge.
The destruction was massive. The immediate damage caused by the blast wave, felt from 37 miles away, destroyed buildings within a 1 mile radius. Witnesses more than five miles from 'ground zero' reported seeing a fireball 10 times the brightness of the sun. The heat from the blast, which reached a temperature of over 7,000 degrees F, caused anything made of paper or cloth to instantly ignite, and the resulting fires damaged or destroyed buildings within 4.4 miles of the blast, effectively destroying two-thirds of the city. The exact number of dead will never be known as the records of the city were incinerated.
Further damaging the city were the winds caused by the blast. It is believed that, as close as one-third of a mile from the center of the explosion, ground wind speeds were about 620 mph, generating roughly 4,600 pounds of pressure per square foot. By the time the winds reached one mile from the blast, they had decreased to 190 mph, which is still fast enough to generate over a thousand pounds of pressure per square foot. To give a sense of what that must have been like, a Category 5 hurricane has sustainable winds speeds of 155 mph or more. Katrina, which hit New Orleans, was only blowing winds of 125 mph when it made landfall, making it a strong Category 3 hurricane at that point. The winds of Hiroshima were strong enough drive broken glass deep into concrete.
Those who survived the initial blast and the resulting fires and winds but were exposed to the massive gamma rays suffered from radiation poisoning. Due to the location of the target being so close to the city's hospitals, 90 percent of the medical personnel were dead, and the remaining medical facilities lacked the ability to handle such a massive number of victims.
To complicate matters, the vacuum caused by the heat's updraft sucked up massive amounts of radioactive dust which rained down 30 minutes later on parts of the city that had been left relatively untouched by the blast wave. One-fifth of the population died within 5 years due to exposure to radiation. Nearly all of those within a half-mile radius of 'ground zero' who survived the initial blast and the fires died within 30 days due to radiation poisoning. Nearly half of those in Hiroshima who died of leukemia and about 10% who died of cancer had their disease as a result of their exposure to radiation.
The Japanese military and civilian leadership were so shocked by the bombing that they denied that the destruction could have been caused by an atomic bomb. Instead, they claimed it must be some new sort of conventional weapon. Sixteen hours later, President Truman sent Japan the message that if it did not offer its unconditional surrender immediately, the US would be forced to repeat its action on another of Japan's cities. Three days after the bombing of Hiroshima, Nagasaki was targeted. Coming only one day after the Soviets had entered the Pacific theater, it was clear that the US was willing to force the issue quickly.
Overruling the objections of the military, Emperor "Tenno" Hirohito demanded that the country begin the negotiations that would lead to surrender. President Truman suspended all further atomic attacks on the Japanese mainland. That did not, however, end the conventional bombing of Japan. As the military and civilian leadership of Japan dickered over the terms, aerial bombing of Tokyo resumed. To further force the issue, the US dropped leaflets on the population that explained the terms that had been offered. On August 15, the citizens of Japan heard for the first time the voice of their emperor, recorded so that there would be no question as to his "divine" will, as he read the country's acceptance of the terms of surrender. Citing the fact that "the enemy has begun to employ a new and most cruel bomb", he acknowledged that continuing the war was not to Japan's advantage.
The nuclear weapons genie will not return to its bottle. In viewing the destructive power of Little Boy, the co-pilot of the Enola Gay, Captain Robert Lewis, uttered the immortal words, "My God, what have we done?". Some have argued that the death caused by those two bombs are outweighed by those that would have been caused on both sides by a conventional invasion of Japan. The projected US casualties due to an invasion were set at around 500,000. The question posed to the War and Peace students this summer was simple: When is is acceptable to resort to nuclear weapons? There's no clear answer to this question.
What I can say is that I've been to Hiroshima and its Peace Park. I've seen the memorials and read the tales. I've touched the "Shadow of Buddha" statue and felt powerful emotional draw that forced my eyes straight upward, to where the hypocenter had been, some 600 yards above me. There are some places in the world where an event leaves a lasting impression. Hiroshima is one such place.
Perhaps having been to see the Peace Park and its museum is the reason I was sadden by the passing in January of this year at the age of 93 of the man who had survived both the Hiroshima and Nagasaki bombings. His outlook on life is one we all should take to heart:
"I could have died on either of those two days. Everything that follows is a bonus."
Hiroshima Before and After: http://www.ibiblio.org/hyperwar/AAF/USSBS/AtomicEffects/AtomicEffects-2.html
Atomic Dome: La Professora's personal travel photos.