Part 2 (1/2)

D. The first target should be relatively untouched by previous bombing, in order that the effect of a single atomic bomb could be determined.

The weather records showed that for five years there had never been two successive good visual bombing days over Tokyo, indicating what might be expected over other targets in the home islands. The worst month of the year for visual bombing was believed to be June, after which the weather should improve slightly during July and August and then become worse again during September. Since good bombing conditions would occur rarely, the most intense plans and preparations were necessary in order to secure accurate weather forecasts and to arrange for full utilization of whatever good weather might occur. It was also very desirable to start the raids before September.

DESCRIPTION OF THE CITIES BEFORE THE BOMBINGS

Hiros.h.i.+ma

The city of Hiros.h.i.+ma is located on the broad, flat delta of the Ota River, which has 7 channel outlets dividing the city into six islands which project into Hiros.h.i.+ma Bay. The city is almost entirely flat and only slightly above sea level; to the northwest and northeast of the city some hills rise to 700 feet. A single hill in the eastern part of the city proper about 1/2 mile long and 221 feet in height interrupted to some extent the spreading of the blast damage; otherwise the city was fully exposed to the bomb. Of a city area of over 26 square miles, only 7 square miles were completely built-up. There was no marked separation of commercial, industrial, and residential zones. 75% of the population was concentrated in the densely built-up area in the center of the city.

Hiros.h.i.+ma was a city of considerable military importance. It contained the 2nd Army Headquarters, which commanded the defense of all of southern j.a.pan. The city was a communications center, a storage point, and an a.s.sembly area for troops. To quote a j.a.panese report, ”Probably more than a thousand times since the beginning of the war did the Hiros.h.i.+ma citizens see off with cries of 'Banzai' the troops leaving from the harbor.”

The center of the city contained a number of reinforced concrete buildings as well as lighter structures. Outside the center, the area was congested by a dense collection of small wooden workshops set among j.a.panese houses; a few larger industrial plants lay near the outskirts of the city. The houses were of wooden construction with tile roofs.

Many of the industrial buildings also were of wood frame construction.

The city as a whole was highly susceptible to fire damage.

Some of the reinforced concrete buildings were of a far stronger construction than is required by normal standards in America, because of the earthquake danger in j.a.pan. This exceptionally strong construction undoubtedly accounted for the fact that the framework of some of the buildings which were fairly close to the center of damage in the city did not collapse.

The population of Hiros.h.i.+ma had reached a peak of over 380,000 earlier in the war but prior to the atomic bombing the population had steadily decreased because of a systematic evacuation ordered by the j.a.panese government. At the time of the attack the population was approximately 255,000. This figure is based on the registered population, used by the j.a.panese in computing ration quant.i.ties, and the estimates of additional workers and troops who were brought into the city may not be highly accurate. Hiros.h.i.+ma thus had approximately the same number of people as the city of Providence, R.I., or Dallas, Tex.

Nagasaki

Nagasaki lies at the head of a long bay which forms the best natural harbor on the southern j.a.panese home island of Kyushu. The main commercial and residential area of the city lies on a small plain near the end of the bay. Two rivers divided by a mountain spur form the two main valleys in which the city lies. This mountain spur and the irregular lay-out of the city tremendously reduced the area of destruction, so that at first glance Nagasaki appeared to have been less devastated than Hiros.h.i.+ma.

The heavily build-up area of the city is confined by the terrain to less than 4 square miles out of a total of about 35 square miles in the city as a whole.

The city of Nagasaki had been one of the largest sea ports in southern j.a.pan and was of great war-time importance because of its many and varied industries, including the production of ordnance, s.h.i.+ps, military equipment, and other war materials. The narrow long strip attacked was of particular importance because of its industries.

In contrast to many modern aspects of Nagasaki, the residences almost without exception were of flimsy, typical j.a.panese construction, consisting of wood or wood-frame buildings, with wood walls with or without plaster, and tile roofs. Many of the smaller industries and business establishments were also housed in wooden buildings or flimsily built masonry buildings. Nagasaki had been permitted to grow for many years without conforming to any definite city zoning plan and therefore residences were constructed adjacent to factory buildings and to each other almost as close as it was possible to build them throughout the entire industrial valley.

THE ATTACKS

Hiros.h.i.+ma

Hiros.h.i.+ma was the primary target of the first atomic bomb mission. The mission went smoothly in every respect. The weather was good, and the crew and equipment functioned perfectly. In every detail, the attack was carried out exactly as planned, and the bomb performed exactly as expected.

The bomb exploded over Hiros.h.i.+ma at 8:15 on the morning of August 6, 1945. About an hour previously, the j.a.panese early warning radar net had detected the approach of some American aircraft headed for the southern part of j.a.pan. The alert had been given and radio broadcasting stopped in many cities, among them Hiros.h.i.+ma. The planes approached the coast at a very high alt.i.tude. At nearly 8:00 A.M., the radar operator in Hiros.h.i.+ma determined that the number of planes coming in was very small--probably not more than three--and the air raid alert was lifted. The normal radio broadcast warning was given to the people that it might be advisable to go to shelter if B-29's were actually sighted, but no raid was expected beyond some sort of reconnaissance.

At 8:15 A.M., the bomb exploded with a blinding flash in the sky, and a great rush of air and a loud rumble of noise extended for many miles around the city; the first blast was soon followed by the sounds of falling buildings and of growing fires, and a great cloud of dust and smoke began to cast a pall of darkness over the city.

At 8:16 A.M., the Tokyo control operator of the j.a.panese Broadcasting Corporation noticed that the Hiros.h.i.+ma station had gone off the air.

He tried to use another telephone line to reestablish his program, but it too had failed. About twenty minutes later the Tokyo railroad telegraph center realized that the main line telegraph had stopped working just north of Hiros.h.i.+ma. From some small railway stops within ten miles of the city there came unofficial and confused reports of a terrible explosion in Hiros.h.i.+ma. All these reports were transmitted to the Headquarters of the j.a.panese General Staff.

Military headquarters repeatedly tried to call the Army Control Station in Hiros.h.i.+ma. The complete silence from that city puzzled the men at Headquarters; they knew that no large enemy raid could have occurred, and they knew that no sizeable store of explosives was in Hiros.h.i.+ma at that time. A young officer of the j.a.panese General Staff was instructed to fly immediately to Hiros.h.i.+ma, to land, survey the damage, and return to Tokyo with reliable information for the staff. It was generally felt at Headquarters that nothing serious had taken place, that it was all a terrible rumor starting from a few sparks of truth.

The staff officer went to the airport and took off for the southwest.