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By the 8th of May,1945, Germany had officerly surrendered to the Allies, which marked the end of World War II in Europe, however, the conflict will continue in the East for almost another four months as Japan refused to surrender itself to the U.S. After countless bloody battles with the Japanese, the U.S. made the decision to end the war much more quickly using their new atomic bomb, which would significally reduce the number of potential causalities on the American side. Now, the Americans only had to drop the actual bomb on Japan, which would, in their hopes, make them surrender.

The only Allied aircraft capable of carrying the 5.2 m long Thin Man or the 150 cm wide Fat Man was the British Avro Lancaster. The Chief of United States Army Air Forces (USAAF), General Henry H. Arnold, assured Groves that no effort would be spared to modify B-29s to carry atomic bombs. In November of 1943, the Army Air Forces Materiel Command at Wright Field began Silverplate, the codename for the modification of the to carry atomic bombs. Test drops were carried out at Muroc Army Air Field and the Naval Ordnance Test Station in California with Thin Man and Fat Man pumpkin bombs to test their ballistic, fuzing and stability characteristics. The 509th Composite Group was activated on the 17th of December, 1944, at Wendover Army Air Field, Utah, under the command of Colonel Paul W. Tibbets. Training was conducted at Wendover and at Batista Army Airfield, Cuba, where the 393rd Bombardment Squadron practiced long-distance flights over water and dropped pumpkin bombs. Roosevelt instructed Groves that Project Alberta was formed at Los Alamos under Parsons' command to assist in preparing and delivering the bombs. Commander Frederick L. Ashworth from Alberta met with Fleet Admiral Chester W. Nimitz on Guam in February of 1945 and selected North Field on Tinian as a base for the 509th Composite Group. Farrell arrived at Tinian on the 30th of July as the Manhattan Project representative and Purnell went to Tinian as the representative of the Military Policy Committee. Most of the components for Little Boy left San Francisco on the cruiser USS Indianapolis on the 16th of July and arrived on Tinian ten days later. Two Fat Man assemblies travelled to Tinian in specially modified 509th Composite Group B-29s. In late April, a joint targeting committee of the Manhattan District and USAAF was established to determine which cities in Japan should be targets, but Secretary of War Henry L. Stimson intervened, announcing that he would not authorize the bombing of Kyoto on the grounds of its historical and religious significance. Groves asked Arnold to remove Kyoto from the list of nuclear targets, and Nagasaki was substituted.




















The Interim Committee was created in May 1945 to advise on wartime and post-war usage of nuclear energy. It was chaired by Stimson, with James F. Byrnes as President Harry S. Truman's personal representative, Ralph A. Bard, William L. Clayton, Vannevar Bush, Karl T. Compton, James B. Conant, and George L. Harrison as assistants. To advise it on scientific matters, the Interim Committee in turn assembled a scientific panel consisting of Arthur Compton, Fermi, Lawrence, and Oppenheimer. The scientific panel provided its assessment of the anticipated physical impacts of an atomic bomb as well as its likely military and political effects in its presentation to the Interim Committee.

Truman learned about the Trinity test's success at the Potsdam Conference in Germany. Without providing any further information, he informed Stalin, the leader of the Soviet Union, that the US had a new superweapon. Stalin previously knew about the bomb from spies, despite the fact that this was the first formal disclosure about it to the Soviet Union. After Japan rejected the Potsdam Declaration, the decision to deploy the bomb against it was made with no other options being considered.

The mission's main objective was Hiroshima, with Kokura and Nagasaki as backups. Hiroshima served as the headquarters of the 2nd General Army and Fifth Division as a port of embarkation. Parsons, the weaponeer in command of the operation, assembled the bomb in the air with Farrell's approval to reduce the possibility of a nuclear explosion in the case of a crash during take-off. The explosion from the bomb, which went off at a height of 530 meters, was eventually calculated to be the equivalent of 13 kilotons of TNT. About 12 km² of land were devastated. According to Japanese authorities, 69% of Hiroshima's structures were destroyed and another 6-7% sustained damage. A total of 70,000 to 80,000 individuals, or about 30% of Hiroshima's population, were killed instantly, including 20,000 Japanese fighters and 20,000 Korean slave workers. This, however, did not encourage the Japanese enough to surrender, so it was too early to celebrate.














On the morning of the 9th of August, 1945, a second B-29 (Bockscar), commanded by Major Charles W. Sweeney of the 393d Bombardment Squadron, took off with the Fat Man. This time, Kokura was the main objective, and Ashworth was the weaponeer. The weapon was already armed when Sweeney took off, but the electrical safety plugs were still in place. When they arrived in Kokura, they discovered that cloud cover had veiled the city, making it impossible to conduct the ordered visual attack. They made three passes over the city before turning toward Nagasaki, their secondary objective, as their fuel supply was running short. A brief break in the clouds above Nagasaki allowed a visual approach as instructed, notwithstanding Ashworth's decision to employ a radar approach if the target was concealed. Between the Mitsubishi Steel and Arms Works in the south and the Mitsubishi-Urakami Ordnance Works in the north, The Fat Man was dropped over the city's industrial valley. About 44% of the city was destroyed as a result of the explosion, which was limited to the Urakami Valley and had a blast yield similar to 21 kilotons of TNT, or about the same as the Trinity test. A significant chunk of the city was shielded by the intervening hills. The bombing also severely hindered the city's industrial output and resulted in the deaths of 150 Japanese soldiers and between 23,200 and 28,200 Japanese industrial employees. Approximately 35,000–40,000 fatalities and 60,000 injuries were reported overall.











Groves anticipated having another nuclear weapon prepared for deployment on the19th of August as well as three more in September and three more in October. On August 11th and 14th, two additional Fat Man assemblies were prepared and slated to depart Kirtland Field for Tinian. To cast a new plutonium core, experts at Los Alamos worked nonstop for 24 hours. Even though it had been cast, it still needed to be coated and pressed, which would take until the 16th of August. Therefore, it might have been prepared for use on the 19th of August. 


The surrender of the Empire of Japan in World War II was announced by Emperor Hirohito on the 15th of August, so Truman quietly asked that no additional atomic bombs were currently needed. Groves, acting alone, stopped the third core's delivery on the 13th of August.

The Japanese surrender would be formally signed on the 2nd of September, 1945.

Groves was instructed to put together a survey team to provide a report on the damage and radiation at Hiroshima and Nagasaki over the phone to Warren on the 11th of August. On the 8th of September, a group led by Farrell and Warren and carrying portable Geiger counters as well as Japanese Rear Admiral Masao Tsuzuki, who served as a translator, arrived at Hiroshima. They stayed in Hiroshima until the 14th of September before conducting surveys in Nagasaki from September 19 through October 8. This and later scientific voyages to Japan brought back useful information, both historically and scientifically.

The necessity of those bombings is still an active discussion between scientists, historians and common people to this day.




Silverplate B-29 Straight Flush. The tail code of the 444th Bombardment Group is painted on for security reasons.
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The mushroom cloud over Hiroshima after the dropping of Little Boy
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The mushroom cloud over Nagasaki after the dropping of Fat Man
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