Importance of the Atomic Bomb; Devastation to Japan

Victory In The Pacific and the Japanese Surrender
  • What was the Manhattan Project: This was a secret, government project founded to produce a weapon that would end all wars for good. Dr. J. Robert Oppenheimer and Albert Einstein were the two leading scientists in the creation of the Atomic Bomb. The project officially lasted four years, from August 1942 to August 1946 ("The Manhattan Project (and Before)"). Previous tests had failed because the uranium was not heavy enough to cause an explosion. With the discovery of U-235, weapons grade uranium, tests were successful. When the first test in Alamogordo, New Mexico on July 16, 1943 was a brilliant success he decided to give Japan an ultimatum: the Potsdam Ultimatum.

J. Robert Oppenheimer proudly displays a mushroom cloud
J. Robert Oppenheimer proudly displays a mushroom cloud

  • What warning did the advisors have for Truman about an invasion of Japan? If a full-scale invasion was launched on Japan, half a million Americans would turn up dead, wounded, or missing (Lee). Truman's original plan for ending the war in Japan was to invade Japan and defeat them there on their on land. But the Japanese homelands were to be defended from invasion and occupation by 2.3 million troops, another 4 million army and navy employees and a newly created armed militia numbering 25 million (Lee). The Japanese were trained to fight to the death to defend their homeland, as they have done in many previous battles. To have effectively invaded Japan, there would have to have been two separate invasions. One invasion, scheduled for November 1945, would need for 770,000 American troops to invade the island of Kyushu (Lee). The following invasion would have been on March, 1946 to invade the city of Tokyo with about 2 million American troops (Lee). But based on the experience at Iwo Jima and Okinawa, it was predicted that in an invasion of Japan, 30% to 35% of U.S. soldiers would be killed or wounded during the first 30 days (Lee).
President Truman during 1945-1953
  • He has an alternative; powerful new weapon: The Atomic Bomb. An alternative decision was brought up about the use of nuclear weapons. The use of the atomic bomb would be an easier way of ending the war much more quickly and also by keeping the American casualty rate down to a minimum. In particular, the bombs used on Hiroshima and Nagasaki were gun triggered. This means that a bullet made of complete uranium-235 is shot down a metal barrel inside the bomb by a small explosion that is remote triggered (Freudenrich). Once the bullet hits the uranium core, the explosion is intiated. This explosion is caused by neutrons that are released that join other atoms and split those. Those atoms that split release more atoms and the chain reaction starts. The process of grabbing a neutron and then releasing another takes a picosecond (0.000000000001) (Freudenrich). The U.S. brings up this idea to the other nations as well and on July 4th, 1945, the British agree to the use of nuclear weaponry against Japan (Lee). On July 16th, during the Potsdam conference, the first Atomic bomb was successfully tested. This was the situation that on July 26th, the U.S., Britain, and China issued the Potsdam Ultimatum to surrender unconditionally (Lee). "The alternative," said the declaration, "is complete and utter destruction."
The atomic bomb "Fat Man"

  • Nagasaki bombed on August 9; 70,000 die immediately: This was not Truman's intended target. Tibbitts was headed for a weapons depot in Kokura, but poor visibility and ground fog caused the drop to be moved to Nagasaki ("Dawn of the Atomic Era"). At 3:47a.m. a B-29 named "Bock's Car," lifted from the island of Tinian toward the primary target of the Kokura Arsenal, a massive collection of war industries next to the city of Kokura. But by the time the B-29 got there, it was covered with smoke and haze. It passed by the point two more times but the target was still covered. One of the crew members pointed out that the Japanese were firing bursts of their anti-aircraft cannons and were making things a little difficult. Kokura was no longer an option and there was only enough fuel to get back to the base at Okinawa. They then decided to go over their secondary target of Nagasaki, since there was no point of either taking the bomb back home or just dropping it in the ocean. At 11:02a.m. at an altitude of 1,650 feet, Fat Man exploded over Nagasaki. The yield of the explosion was later estimated to be 21 kilotons, 40 percent greater than that of the Hiroshima bomb ("Dawn of the Atomic Era").
    Nagasaki after the bombing
  • Atomic bomb dropped on Hiroshima on August 6, 1945: about 75.000 die: Within minutes two-thirds of Hiroshima had been completely destroyed: clay roof tiles melted together, shadows imprinted on the sides of buildings, metal and stone melted, and sand was turned into glass ("Dawn of the Atomic Era"). At exactly 8:16am (Tokyo time) a B-29 bomber named the Enola Gay took off from the island of Tinian and headed North by Northwest toward Japan. The bomber's primary target was on the city of Hiroshima, with a population of about 300,000 and was a important military center with about 43,000 soldiers. Colonel Paul Tibbets dropped the bomb "Little Boy," a 9,700 pound uranium bomb 1,900 feet over the city. Tibbets felt the shock wave of the blast and looked back on the city. "The city was hidden in that awful cloud... Boiling up, mushrooming, terrible and incredibly tall," Tibbets recalled ("Dawn of the Atomic Era"). The yield of the explosion was later estimated at 15 kilotons (around the force of 15,000 tons of TNT). _41357959_hiroshima_1_629.gif.jpeg
    Hiroshima after the bombing

  • Effects on the Japanese cities: You can only imagine the effect a 3,600 kg bomb would have on its target. This was the size of the bomb 'Little Boy' that was dropped on Hiroshima. It had the force of 12.5 kilotons of TNT, that's enough to blow up to entire mountains! Five square miles of Hiroshima were demolished to ash, as well as 2.6 square miles of Nagasaki (Levine). "Fat Man" was dropped on top of schools, factories, and private houses it also had more effect because Nagasaki is in a valley surrounded by mountains, so the blast was more concentrated. A benefit of this, however, is that some of the blast was contained in those mountains, so it didn't spread as quickly to other cities. 22.7% of the buildings in Nagasaki were completely gone, but 36.1% of the buildings were unharmed. In Nagasaki, about 73,884 people were killed and 74,909 were injured by the blast. Of the people that were wounded almost every one died due to the amount of radiation in their bodies or to mental trauma. In Hiroshima, there was about a 50% instant death rate in the .74 mile hypocentre in which there were about 350,000 people! There was an estimated death toll of about 118,661 citizens, 20,000 soldiers, and 140,000 people in that area have since died because of radiation sickness (Levine).
    All that remains of Nagasaki
  • What happened on September 2, 1945? In the August of 1945, the Japanese situation was desperate. The major cities were devastated and the casualties numbered in millions. The fleet was lost and the merchant shipping could not leave home waters or sail from the few possessions still held without the chance of a submarine or mine attack. Oil stocks were gone, rubber and steel supplies were low, and the soviets were moving in on the only sizable forces the Japanese had left, the Kwantung Army in Manchuria. They were a starving and under-supplied force. Many divisions had transferred to the Pacific, where they died in the island battles. In the morning of September 2nd, 1945, more than 2 weeks after accepting the allies terms, Japan formally surrendered. The ceremonies, less than half an hour long, took place on board the battleship USS Missouri, anchored with other U.S. and British ships in Tokyo Bay.
    Japanese surrendering on the USS Missouri

  • Effects of radiation on Japanese citizens: Although the explosion killed 70,000 instantly in Nagasaki and 75,000 in Hiroshima, the radiation killed hundreds of thousands more. Slight exposure to radiation can cause nausea, vomiting, headache, and a small loss of white blood cells. Radiation exposure is measured in rems. Over 300 rems can cause temporary hair loss, damage to nerve cells and the cells that line the digestive tract, severe loss of white blood cells, and reduced production of blood platelets. Half of all people that are exposed to 450 rems die, and individuals who are exposed to 800 rems or more are sure to die, some die within the half hour of exposure (Levine). People also died because of the severe burns on their backs due to the intense heat of the explosion. Most Japanese doctors suffered from the radiation carried by their patients. Dr. Akizuki said," All of us suffered from diarrhea and a discharge of blood from the gums, but we kept this to ourselves. Each of us thought tomorrow it might be me... We became stricken with fear of the future" (Levine).

  • Effects on Enviorment: The effect of the bomb left absolutely everything in a complete mess. Everything within a 15-mile radius was completely obliterated. Any water in the area either evaporated or became polluted with radiation. Anything that would touch the water was exposed to radiation. Also, the bomb created a substance called "Black Rain," leaving radioactive debris falling heavily for more than an hour after the explosion. Any plants in the area most likely were to have been incinerated from the blast or would eventually die from the radioactive air. This was also true with people and animals. Prolonged exposure to the radiation would give people radiation poisoning. It would also give things similar to cancer.

Works Cited

Dinks, David. "Why did President Truman Drop the Atomic Bomb?" 2002. <>. 8 May, 2009

"File: Nagasaki 1945-Before and After (adjusted).jpg." 28 April, 2009. <>.
8 May, 2009.

Freudenrich, Craig. "How Nuclear Bombs Work." <>. 14 May, 2009.

Gerdes I., Louise. The 1940's. San Diego: Greenhaven, 2004.

Lee, Bruce. "Why Truman Bombed Hiroshima." <>. 8 May, 2009.

Levine, Philip. "A Photo-Essay on the Bombing of Hiroshima and Nagasaki." <>. 13 May, 2009.

"The Manhattan Project (and Before)." 30 Mar. 1999. <>. 7 May, 2009.

Naff Farris, Clay. The History of Nations: Japan. San Diego: Greenhaven, 2004.

"President Truman Pictures." 1998. <>. 8 May, 2009.

Rosenburg, Jennifer. "Hiroshima and Nagasaki." <>. 7 May, 2009.

Streissguth, Tom. Nuclear Weapons: More Countries, More Threats. New Jersey: Enslow, 2000.

"Underwater Atomic Bomb Test at Bikini Atoll." 5 March, 2008. <>. 5 May, 2009.