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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 Hiroshima 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 Gayindicating 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 control over to his bombardier.
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 (18.5 km) 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% 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
For six months before the atomic bombings, the United States intensely fire-bombed 67 Japanese cities. Together with the United Kingdom and the Republic of China, the United States called for a surrender of Japan in the Potsdam Declaration on July 26, 1945. The Japanese government ignored this ultimatum. By executive order of President Harry S. Truman, the U.S. dropped the nuclear weapon “Little Boy” on the city of Hiroshima on Monday, August 6, 1945, followed by the detonation of “Fat Man” over Nagasaki on August 9.
Within the first two to four months of the bombings, the acute effects killed 90,000–166,000 people in Hiroshima and 60,000–80,000 in Nagasaki, with roughly half of the deaths in each city occurring on the first day. The Hiroshima prefectural health department estimates that, of the people who died on the day of the explosion, 60% died from flash or flame burns, 30% from falling debris and 10% from other causes. During the following months, large numbers died from the effect of burns, radiation sickness, and other injuries, compounded by illness. In a US estimate of the total immediate and short term cause of death, 15–20% died from radiation sickness, 20–30% from flash burns, and 50–60% from other injuries, compounded by illness. In both cities, most of the dead were civilians
The “Fat Man” weapon, containing a core of ~6.4 kg (14.1 lbs.) of plutonium-239, was dropped over the Nagasaki city’s industrial valley. It exploded 43 seconds later at 469 meters (1,540 ft) above the ground exactly halfway between the Mitsubishi Steel and Arms Works in the south and the Mitsubishi-Urakami Ordnance Works (Torpedo Works) in the north. This was nearly 3 kilometers (2 mi) northwest of the planned hypocenter; the blast was confined to the Urakami Valley and a major portion of the city was protected by the intervening hills. The resulting explosion had a blast yield equivalent to 21 kilotons of TNT (88 TJ). The explosion generated heat estimated at 3,900 degrees Celsius (4,200 K, 7,000 °F) and winds that were estimated at 1005 km/h (624 mph).
People who suffered the effects of both bombings are known as nijū hibakusha in Japan. On March 24, 2009, the Japanese government officially recognized Tsutomu Yamaguchi (1916–2010) as a double hibakusha. He was confirmed to be 3 kilometers from ground zero in Hiroshima on a business trip when Little Boy was detonated. He was seriously burnt on his left side and spent the night in Hiroshima. He arrived at his home city of Nagasaki on August 8, a day before Fat Man was dropped, and he was exposed to residual radiation while searching for his relatives. He was the first officially recognised survivor of both bombings. Tsutomu Yamaguchi died on January 4, 2010, after a battle with stomach cancer at the age of 93.The 2006 documentary Twice Survived: The Doubly Atomic Bombed of Hiroshima and Nagasaki documented 165 nijū hibakusha, and was screened at the United Nations.
Six days after the detonation over Nagasaki, on August 15, Japan announced its surrender to the Allied Powers, signing theInstrument of Surrender on September 2, officially ending the Pacific War and therefore World War II. Germany had signed itsInstrument of Surrender on May 7, ending the war in Europe. The bombings led, in part, to post-war Japan’s adopting Three Non-Nuclear Principles, forbidding the nation from nuclear armament. The role of the bombings in Japan’s surrender and the U.S.’sethical justification for them, as well as their strategic importance, is still debated.
now the thing which is bothering me very much is that why now, i mean why america is against all he nations which are storing nuclear warheads for their defense! is DEFENSE a term use only for americans?
point to ponder!!
for american government and their people, the atomic bombing on japan is justified, but what the hell… why do they oppose other countries for doing the same for their defense! ULTIMATE HYPOCRISY!!!!
food for thought!!