The U.S. bombing of the Japanese city of Hiroshima was the first use of the atomic bomb. On July 25,1945, commander of U.S. Strategic Air Forces, Gen. Carl Spaatz received orders to use the 509th Composite Group, 20th Air Force, to deliver a “special bomb” attack on selected target cities in Japan, specifically Hiroshima, Kokura, Niigata, or Nagasaki. Following rejection of conditions promulgated by the Potsdam Proclamation on July 26, a declaration threatening Japan with total destruction if unconditional surrender was not accepted, President Harry S Truman authorized use of the special bomb.
Assembled in secrecy and loaded on the Boeing B-29 Superfortress Enola Gay, the bomb consisted of a core of uranium isotope 235 shielded by several hundred pounds of lead, encased in explosives designed to condense the uranium and initiate a fission reaction. Nicknamed “Little Boy,” the bomb possessed a force equivalent to 12,500 tons of TNT (12.5 kilotons).
The Enola Gay, commanded by Col. Paul Tibbets, departed Tinian at 2:45 a.m. on August 6. Two B-29s assigned as scientific and photographic observers followed, and the three aircraft rendezvoused over Iwo Jima for the run over Japan. Capt. William Parsons of the U.S. Navy completed the bomb's arming in the air shortly after 6:30 a.m. The flight to Japan was uneventful, and Tibbets was informed at 7:47 a.m. by weather planes over the targets that Hiroshima was clear for bombing. Japan's eighth largest city (it had about 245,000 residents in August 1945), Hiroshima was an important port on southern Honshu and headquarters of the Japanese Second Army.
The Enola Gay arrived over the city at an altitude of 31,600 feet and dropped the bomb at 8:15:17 a.m. local time. After a descent of some nearly 6 miles, the bomb detonated 43 seconds later, some 1,890 feet over a clinic and about 800 feet from the aiming point, Aioi Bridge. The initial fireball expanded to 110 yards in diameter, generating heat in excess of 300,000 degrees Centigrade, with core temperatures over 50 million degrees Centigrade. At the clinic directly beneath the explosion, the temperature was several thousand degrees. The immediate concussion destroyed almost everything within 2 miles of ground zero. The resultant mushroom cloud rose to 50,000 feet and was observed by B-29s more than 360 miles away. After 15 minutes, the atmosphere dropped radioactive black rain, adding to the death and destruction.
Four square miles of Hiroshima's heart disappeared in seconds, including 62,000 buildings. More than 71,000 Japanese died, another 20,000 were wounded, and 171,000 were left homeless. Some estimates place the number of killed at more than 200,000. About one-third of those killed instantly were soldiers. Most elements of the Japanese Second General Army were at physical training on the grounds of Hiroshima Castle when the bomb exploded. Barely 900 yards from the explosion's epicenter, the castle and its residents were vaporized. Also killed was one American prisoner of war in the exercise area. All died in less than a second. Radiation sickness began the next day and added to the death toll over several years.
Following three observation circuits over Hiroshima, the Enola Gay and its escorts turned for Tinian, touching down at 2:58 p.m. The bombing mission, 12 hours and 13 minutes long covering 2,960 miles, changed the nature of warfare, but did not end the war. Truman released a statement on August 7, describing the weapon and calling on Japan to surrender, but his message was ignored by most Japanese leaders as propaganda. The United States dropped another atomic bomb on August9, this time on Nagasaki. Although the bomb missed its intended aiming point by 8,500 ft, it leveled one-third of the city. Called the Red Circle of Death, the fire and blast area within the Urakami Valley section of Nagasaki destroyed more than 18,000 homes and killed 74,000 people. Another 75,000 were injured, and many later died from wounds or complications.
Survivors of the nuclear bombings of Hiroshima and Nagasaki are known as hibakusha and currently number at some 300,000. Many of them suffer from disfiguration and radiation-related illnesses, some of which have affected and will affect future generations. In 1996, the International Court of Justice issued an advisory opinion in which it found that “the threat or use of nuclear weapons would generally be contrary to the rules of international law applicable in armed conflict, and in particular the principles and rules of humanitarian law.” (ICJ Opinion, 44) The court was unable to decide, however, whether or not such threat or use would be illegal in “an extreme circumstance of self-defense, in which the very survival of a State would be at stake.” Since international humanitarian law was already in place at the end of World War II and the survival of the United States was not at stake, some scholars suggest that that the bombings of Hiroshima and Nagasaki could be considered illegal acts of war that violated international humanitarian law by attacking civilian populations and causing unnecessary suffering to combatants.
See also: Legitimate Military Targets; Tokyo, Bombing of (1945).
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