Hiroshima

At the time of its bombing, Hiroshima was a city of some industrial and military significance. A number of military camps were located nearby, including the headquarters of the Fifth Division and Field Marshal Shunroku Hata's 2nd General Army Headquarters, which commanded the defense of all of southern Japan. Hiroshima was a minor supply and logistics base for the Japanese military. The city was a communications center, a storage point, and an assembly area for troops. It was one of several Japanese cities left deliberately untouched by American bombing, allowing a pristine environment to measure the damage caused by the atomic bomb.

The center of the city contained several reinforced concrete buildings and lighter structures. Outside the center, the area was congested by a dense collection of small wooden workshops set among Japanese houses. A few larger industrial plants lay near the outskirts of the city. The houses were constructed of wood with tile roofs, and many of the industrial buildings were also built around wood frames. The city as a whole was highly susceptible to fire damage.

The population of Hiroshima had reached a peak of over 381,000 earlier in the war, but prior to the atomic bombing the population had steadily decreased because of a systematic evacuation ordered by the Japanese government. At the time of the attack, the population was approximately 340,000–350,000. Because official documents were burned, the exact population is uncertain.

Hiroshima was the primary target of the first nuclear bombing mission on August 6, with Kokura and Nagasaki being alternative targets. August 6 was chosen because clouds had previously obscured the target. The 393d Bombardment Squadron B-29 Enola Gay, piloted and commanded by 509th Composite Group commander Colonel Paul Tibbets, was launched from North Field airbase on Tinian in the West Pacific, about six hours flight time from Japan. The Enola Gay (named after Colonel Tibbets' mother) was accompanied by two other B-29s. The Great Artiste, commanded by Major Charles W. Sweeney, carried instrumentation; and a then-nameless aircraft later called Necessary Evil (the photography aircraft) was commanded by Captain George Marquardt.

After leaving Tinian the aircraft made their way separately to Iwo Jima where they rendezvoused at 2,440 meters (8,010 ft) and set course for Japan. The aircraft arrived over the target in clear visibility at 9,855 meters (32,333 ft). During the journey, Navy Captain William Parsons had armed the bomb, which had been left unarmed to minimize the risks during takeoff. His assistant, 2nd Lt. Morris Jeppson, removed the safety devices 30 minutes before reaching the target area.

About an hour before the bombing, Japanese early warning radar detected the approach of some American aircraft headed for the southern part of Japan. An alert was given and radio broadcasting stopped in many cities, among them Hiroshima. At nearly 08:00, the radar operator in Hiros

hima determined that the number of planes coming in was very small—probably not more than three—and the air raid alert was lifted. To conserve fuel and aircraft, the Japanese had decided not to intercept small formations. The normal radio broadcast warning was given to the people that it might be advisable to go to air-raid shelters if B-29s were actually sighted. However a reconnaissance mission was assumed because at 07.31 the first B29 to fly over Hiroshima at 32,000 feet (9,800 m) had been the weather observation aircraft Straight Flush that sent a morse code message to the Enola Gay indicating that the weather was good over the primary target and because it then turned out to sea the 'all clear' was sounded in the city. At 08.09 Colonel Tibbets started his bomb run and handed over to his bomb aimer.

The release at 08:15 (Hiroshima time) went as planned, and the gravity bomb known as "Little Boy", a gun-type fission weapon with 60 kilograms (130 lb) of uranium-235, took 43 seconds to fall from the aircraft flying at 31,060 feet (9,470 m) to the predetermined detonation height about 1,900 feet (580 m) above the city. The Enola Gay had traveled 11.5 miles away before it felt the shock waves from the blast.
Due to crosswind, it missed the aiming point, the Aioi Bridge, by almost 800 feet (240 m) and detonated directly over Shima Surgical Clinic. It created a blast equivalent to about 13 kilotons of TNT (54 TJ). (The U-235 weapon was considered very inefficient, with only 1.38% of its material fissioning.) The radius of total destruction was about one mile (1.6 km), with resulting fires across 4.4 square miles (11 km2). Americans estimated that 4.7 square miles (12 km2) of the city were destroyed. Japanese officials determined that 69% of Hiroshima's buildings were destroyed and another 6–7% damaged.

70,000–80,000 people, or some 30%[34] of the population of Hiroshima were killed immediately, and another 70,000 injured. Over 90% of the doctors and 93% of the nurses in Hiroshima were killed or injured—most had been in the downtown area which received the greatest damage.

Although the U.S. had previously dropped leaflets warning civilians of air raids on 35 Japanese cities, including Hiroshima and Nagasaki, the residents of Hiroshima were given no notice of the atomic bomb.
According to the U.S. Department of Energy the immediate effects of the blast killed approximately 70,000 people in Hiroshima. Estimates of total deaths by the end of 1945 from burns, radiation and related disease, the effects of which were aggravated by lack of medical resources, range from 90,000 to 166,000.Some estimates state up to 200,000 had died by 1950, due to cancer and other long-term effects. Another study states that from 1950 to 1990, roughly 9% of the cancer and leukemia deaths among bomb survivors was due to radiation from the bombs, the statistical excess being estimated to 89 leukemia and 339 solid cancers. At least eleven known prisoners of

war died from the bombing.

Some of the reinforced concrete buildings in Hiroshima had been very strongly constructed because of the earthquake danger in Japan, and their framework did not collapse even though they were fairly close to the blast center. Eizo Nomura (野村 英三, Nomura Eizō?) was the closest known survivor, who was in the basement of a reinforced concrete building (it remained as the Rest House after the war) only 170 m (560 ft) from ground zero (the hypocenter) at the time of the attack. Akiko Takakura (高蔵 信子, Takakura Akiko?) was among the closest survivors to the hypocenter of the blast. She had been in the solidly built Bank of Hiroshima only 300 meters (980 ft) from ground-zero at the time of the attack. Since the bomb detonated in the air, the blast was directed more downward than sideways, which was largely responsible for the survival of the Prefectural Industrial Promotional Hall, now commonly known as the Genbaku, or A-bomb Dome. This building was designed and built by the Czech architect Jan Letzel, and was only 150 m (490 ft) from ground zero. The ruin was named Hiroshima Peace Memorial and was made a UNESCO World Heritage site in 1996 over the objections of the U.S. and China. The Memorial monument for Hiroshima was built in Hiroshima for bombing victims.

Japanese realization of the bombing;;The Tokyo control operator of the Broadcasting Corporation of Japan noticed that the Hiroshima station had gone off the air. He tried to re-establish his program by using another telephone line, but it too had failed. About 20 minutes later the Tokyo railroad telegraph center realized that the main line telegraph had stopped working just north of Hiroshima. From some small railway stops within 16 kilometers (10 mi) of the city came unofficial and confused reports of a terrible explosion in Hiroshima. All these reports were transmitted to the headquarters of the Imperial Japanese Army General Staff.

Military bases repeatedly tried to call the Army Control Station in Hiroshima. The complete silence from that city puzzled the men at headquarters; they knew that no large enemy raid had occurred and that no sizeable store of explosives was in Hiroshima at that time. A young officer of the Japanese General Staff was instructed to fly immediately to Hiroshima, 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 and that the explosion was just a rumor.

The staff officer went to the airport and took off for the southwest. After flying for about three hours, while still nearly 100 miles (160 km) from Hiroshima, he and his pilot saw a great cloud of smoke from the bomb. In the bright afternoon, the remains of Hiroshima were burning. Their plane soon reached the city, around which they circled in disbelief. A great scar on the land still burning and covered by a heavy cloud of smoke was all that was left. The

y landed south of the city, and the staff officer, after reporting to Tokyo, immediately began to organize relief measures.

By August 8, 1945, newspapers in the U.S. were reporting that broadcasts from Radio Tokyo had described the destruction observed in Hiroshima. "Practically all living things, human and animal, were literally seared to death," Japanese radio announcers said in a broadcast received by Allied sources