-Development of a New Weapon-

Nuclear weapons are developed for genocide and mass destruction, utilizing the energy released when nuclear fission occurs.

Their destructive powers are enormous. Compared to weapons with a conventional explosive, the energy of the Hiroshima-type atomic bomb, using 12.5 kilogram of uranium-235 (as big as a softball), is equivalent to 15 kilotons of TNT (trinitrotoluene). That means it is one million times more destructive than conventional bombs fired from ordinary cannons.

Although Germany had been ahead of theoretical research in nuclear physics, specialists, mostly of Jewish origin, were expelled from the country by the Nazis in the latter half of 1930s.

Meanwhile, Great Britain recognized the possibility of producing atomic bombs in 1940 during the World War II, and decided to develop atomic bomb cooperating with the U. S. A. by voluntarily providing information, for fear that Germany would develop the atomic bomb faster and would bring a destructive result. Also, in the U. S. A., scientists who escaped from Europe recommended President Roosevelt to develop atomic bombs prior to Germany. The U. S. government and the army were rushing to develop an A-bomb by organizing a group of scientists, putting great sums of money and industry into this project. This is so called "Manhattan Project".

-The Manhattan Project-

The development of new weapons using nuclear energy, i. e. Manhattan Project began in 1942. The U. S. government, nuclear physicists, industrial authorities and U. S. military authorities collaborated with utmost secrecy on the project and steadily advanced the development of atomic bombs. The corps specializing on dropping an A-bomb by B-29 bomber were formed in the fall of 1944. Germany surrendered in May 1945, and Japan had given up developing A-bombs.

The U. S. A. completed A-bombs and intended to use them in order to take the initiative in the world after war. Three A-bombs were completed and finally, on July 16, 1945, the first A-bomb test in the world was successfully carried out in the desert of Alamogordo, New Mexico. The other two were used in the actual battles in Hiroshima and Nagasaki.

It worked exactly as the U. S. A. had intended. "The U. S. air force dropped an A-bomb 16 hours ago on Hiroshima, where the most important military bases are.", President Truman announced to the whole world. This single drop of A-bomb confirmed U. S. victory over Japan and enhanced U. S. international position. Then the U. S. A. dropped the third A-bomb on Nagasaki. The U. S. A. opened the door of "nuclear age" after that.

The Way the U. S. A. Developed an A-bomb

Jan. 26 A Danish physicist, Niels Bohr announced at an academic meeting in Washington D. C. that he had discovered nuclear fission.
Mar. 3Enrico Fermi, Leo Szilard a refugee scientist from Italy, and another physicist in Hungary successfully experimented with the possibility of achieving a chain reaction in uranium at Columbia University in the U. S. A.
Aug. 2Albert Einstein signed the letter drafted by Szilard in which they recommended to President Franklin D. Roosevelt that the U. S. Army be brought into a project for the construction of plans to produce fissionable materials, emphasizing the danger of Germany develop new energy using uranium.
Jun. 27 National Defense Research Committee (NDRC) was established under the chairmanship of Dr. Vannever Bush.
Apr.Takeo Yasuda, Lieutenant General as well as Director of the Japan Army Air Technical Research asked Dr. Masatoshi Okouchi, Director of The Institute of Physical and Chemical Research to research the atomic bomb.
Oct. 11 President Roosevelt proposed to British Prime Minister, Winston Churchill that the two countries cooperate in developing atomic bomb.
Nov. 28The uranium project of the U. S. A. was moved from NDRC and placed directly under the Office of Scientific Research and Development (OSRD), of which NDRC was a part. The Uranium Committee was established. Sixteen projects had been conducted, totaling about $ 2 billion.
Jan.Nuclear research groups of Columbia University and Princeton University moved to the University of Chicago, and established the Metallurgical Laboratory, under the direction of Dr. Arthur H. Compton to develop the knowledge needed to design, built and operate a plant for the conversion of uranium into plutonium.
Aug. 13The Manhattan Project started under the direction of the Army Corps of Engineers. Brigadier General Leslie R. Groves was placed in charge of the project in September.
Nov.Purchase of a site in Los Alamos, New Mexico to construct a central bomb laboratory.
Dec. 2Enrico Fermi succeeded in producing and controlling a fission chain reaction, using an uranium and graphite atomic pile.
Dr. Yoshio Nishina's research group of the Institute of Physical and Chemical Research made a report, by request of Dr. Masatoshi Okouchi, that the production of atomic bombs was possible, and started research on it.
Jan.Construction began on the Clinton Engineer Works in Oak Ridge, Tennessee.
Mar. 15A nuclear physicist, Dr. J. Robert Oppenheimer was appointed as a director of a laboratory established at Los Alamos, New Mexico.
Apr. 6Construction began on the Hanford Engineer Works in Washington.
Aug.British scientists moved to the U. S. A. to jointly develop atomic bomb.
Nov. 4Operation of the nuclear reactor began at the Clinton Engineer Works.
Feb. 20 Germany gave up developing atomic bombs.
Mar. 12Uranium 235 separating pile was completed in Nishina's laboratory.
Aug. 26Niels Bohr met President Roosevelt and proposed the international control of atomic energy.
Sep. 1Colonel Paul W. Tibbets, Jr. was appointed as a commander of a bomb combat unit, 509th Composite Group (consisting of fourteen B-29s and a crew of 1767, officers and noncommissioned officers put together). After forming the 509th in December, it started training at Wendover field, an isolated air base in western Utah.
Apr. 12 Roosevelt died. Vice President, Harry Truman was inaugurated as president.
  13The Institute of physical and chemical Research housing uranium 235 separating pile was burned down by air-raid in Tokyo. Japan gave up developing the atomic bomb in May.
  25Secretary of the War, Henry L. Stimson and General Groves reported to President Truman that the atomic bomb would be completed within four months.
May 18The 509th Composite Group started moving to Tenian Island.
  28Leo Szilard and others met the Secretary of the State, James F. Byrnes and expressed their objection to using an atomic bomb against Japan.
Jul. 16The U. S. A. succeeded in the first plutonium-type atomic bomb test explosion at Alamogordo, New Mexico.
17In objecting the use of the atomic bomb against Japan, Arthur Compton submitted a petition signed by 67 scientists of the Metallurgical Laboratory to Stimson's advisor, George L. Harrison.
22The Target Committee selected Hiroshima, Kokura, Niigata and Nagasaki as target cities. Kyoto was excluded by Stimson's strong objection.
24President Truman informed the Soviet Prime Minister, Stalin in Potsdam that the U. S. A. succeeded in the development of new weapon and its use against Japan.
25General Thomas Hardy, Acting Chief of Staff ordered General Carl Spaatz of the United States rmy Strategic Air Forces (USASTAF) to visually bomb after August 1 one of the targets: Hiroshima, Kokura, Niigata and Nagasaki.
Aug.1Completed assembling an uranium-type bomb “Little Boy” which was to be dropped on Hiroshima. Niigata was excluded from target cities as being a small city, as well as being too far away from Tinian. The attack unit consisted of seven planes. Three B-29s were on the alert over Hiroshima, Kokura, and Nagasaki to report the weather conditions to Tibbets in Enola Gay and headquarters in both Guam and Tinian. The Enola Gay was followed by two planes: one carrying the bomb measuring instruments and the other carrying a camera. The other plane stayed at Iwojima as a substitute of the Enola Gay.
6At 00:37 (Japan time) three meteorological observing planes took off Tinian base. At 01:45 the Enola Gay, loaded with an atomic bomb, took off from the Tinian runway. At 08:15 the bomb was exploded and the plane returned to the base at 13:58.

Air-raid of Cities All Over Japan

Around the end of the World War II, Japan had no strength left to defend itself against U. S. bombers flying in the sky of Japan. The U. S. A. bombed with B-29s from the air base in the Pacific islands.

From midnight of March 9 until March 10, Tokyo was heavily air-raided. It is said that the city was covered with fire and about 120,000 people were killed or wounded. The U. S. continuously bombed all through Japan, using incendiary bombs, until the end of the war on August 15. The city area, cramped with wooden houses, were more severely devastated than the military facilities. It was not soldiers, but large number of civilians who were killed by theses air raids. This was called "full scale air raid of mainland Japan,"and shelters were built in towns, but they did not help save the lives of many people.

Major Cities That Were Air-Raided
The numbers next to the names of cities indicate numbers of victims
=more than 10,000 victims
* According to "Report of Japan's damage in the War in the Pacific" (1949, Japan Nihon Kezai Antei Honbu)
*92 cities were air-raided according to this data, other data after that amounted to more than 100 cities and towns are air-raided.

-From Tinian Island to the Target City, Hiroshima-

The Enola Gay, a B-29 bomber loaded with an atomic bomb, took off from the U. S. Air Force base on Tinian Island in the Marianas, in the western Pacific. The atomic bomb was carried by a heavy cruiser, the Indianapolis, to the Tinian base and it was loaded onto the Enola Gay on August 5, 1945. One of the twelve-man crew of the Enola Gay was the co-pilot in charge of installing the atomic bomb. In his flight diary during the seven hour flight, he recorded the times for departure, dropping of the bomb and returning as follows:

2:45 a.m.	Take off
3:00 a.m.	Start installing the final triggering device
3:15 a.m.	Finish installing the triggering device
6:05 a.m.	Flying over Iwojima to Japan
7:30 a.m.	Insert the red plug (placing the bomb imposition ready to be exposed when dropped)
7:41 a.m.	Start ascent.  Receive information on weather conditions- fair over the 1st and 3rd         targets but not over 2nd.  
8:38 a.m.	Change to a horizontal flight pattern at an altitude of 32,700 feet (about 9,970           meters)
8:47 a.m.	Test electronic fuses. Result OK.
9:04 a.m.	Change course toward west
9:09 a.m.	The target, Hiroshima in sight
9:15 .30"	(8:15 30" Japan time) Drop A-bomb

As soon as the atomic bomb was visually released, at an altitude of 31,600 feet (about 9,600 meters), the Enola Gay made a quick turn of 158 degrees to the north. It fled away toward the skies of the Sanin district. The destructive power of the uranium bomb was as strong as the U. S. had expected. A plutonium bomb was dropped on Nagasaki three days later.