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READ: Nuclear Weapons

World War Two was unlike any war before. Millions of people died in concentration camps fueled by racism and antisemitism. Hundreds of thousands were killed by a new, powerfully lethal atomic bomb. People have long debated if the use of the atomic bomb was the only way to win the war in the Pacific.
The article below uses “Three Close Reads”. If you want to learn more about this strategy, click here.

First read: preview and skimming for gist

Before you read the article, you should skim it first. The skim should be very quick and give you the gist (general idea) of what the article is about. You should be looking at the title, author, headings, pictures, and opening sentences of paragraphs for the gist.

Second read: key ideas and understanding content

Now that you’ve skimmed the article, you should preview the questions you will be answering. These questions will help you get a better understanding of the concepts and arguments that are presented in the article. Keep in mind that when you read the article, it is a good idea to write down any vocab you see in the article that is unfamiliar to you.
By the end of the second close read, you should be able to answer the following questions:
  1. Where was nuclear fission discovered? How did it get into the hands of the American military?
  2. What was the Potsdam Declaration?
  3. According to Peter Zimmerman, Japanese cities were being bombed every week, with about as many people dying every week as died as a result of the nuclear bomb attack on Hiroshima. What claim does this evidence support?
  4. Why did the Japanese surrender, according to Tsuyoshi Hasegawa?
  5. What ‘race’ did the United States, Soviet Union, United Kingdom, China, France, and India participate in after the Second World War?

Third read: evaluating and corroborating

Finally, here are some questions that will help you focus on why this article matters and how it connects to other content you’ve studied.
At the end of the third read, you should be able to respond to this question:
  1. Tsuyoshi Hasegawa argues that the Soviet Union played a considerable role in Japan’s surrender, more so than American use of nuclear weapons. Do you find the author’s argument convincing? Why or why not? Use evidence from materials from this Era to support your claim.
Now that you know what to look for, it’s time to read! Remember to return to these questions once you’ve finished reading.

Nuclear Weapons

Photograph of a Hiroshima, mostly reduced to rubble, after the atomic bomb.
By Bridgette Byrd O’Connor
World War Two was unlike any war before. Millions of people died in concentration camps fueled by racism and antisemitism. Hundreds of thousands were killed by a new, powerfully lethal atomic bomb. People have long debated if the use of the atomic bomb was the only way to win the war in the Pacific.


In 1938, a small group of German scientists accidentally discovered nuclear fission. They observed that a radioactive atom releases a huge burst of energy when it is split. This new discovery had an immense amount of potential as a weapon of war. As the Nazi regime began instituting more controls on the German people, many scientists fled Germany. Some of these scientists came to the United States and informed the noted scientist Albert Einstein of the power of nuclear fission.
Photograph shows a fire ball just after detonation, which is dome shaped and balanced on a pile of, what looks like, dust.
Trinity site fireball, photo taken 0.016 seconds after detonation on July 16, 1945. Photo taken by Berlyn Brixner. By Los Alamos National Laboratory, public domain
In August 1939, Einstein signed a letter that was sent to the United States' president Franklin D. Roosevelt. The letter warned the president of a new, potentially dangerous weapon. The Einstein-Szilard letter stated "that the element uranium may be turned into a new and important source of energy in the immediate future … This new phenomenon would also lead to the construction of bombs, and it is conceivable—though much less certain—that extremely powerful bombs of a new type may thus be constructed. A single bomb of this type, carried by boat and exploded in a port, might very well destroy the whole port together with some of the surrounding territory…." (Einstein).
Einstein's letter alarmed President Roosevelt. He was concerned that this technology could be used by the Germans against civilians in Europe and America. When Hitler invaded Poland later that year, Roosevelt knew he had to act. As a result, Americans created the Manhattan Project in August 1942. It was a secret mission to harness the power of nuclear fission to create a bomb. Physicist J. Robert Oppenheimer was put in charge of the top-secret project at the New Mexico base. The Manhattan Project was under the direction of the U.S. military. But it was a joint project that included military professionals, scientists, and private companies.
Roosevelt died just prior to the end of the war in Europe in the spring of 1945. However, America's secret weapon was not yet fully tested or operational. In July 1945, the Trinity Test confirmed the power and destructiveness of a controlled nuclear fission bomb.
The new American president was Harry S. Truman. Truman sent an ultimatum to the Japanese emperor. He warned Emperor Hirohito of Japan's "prompt and utter destruction" if they did not unconditionally surrender to the Allies. This warning was called the Potsdam Declaration. On August 6, 1945, a B-29 bomber dropped the first atomic bomb on Hiroshima. Known as "Little Boy", the bomb was dropped from a plane named the Enola Gay. Approximately 80,000 Japanese citizens were killed instantly. The explosion leveled an area that encompassed five square miles. But Emperor Hirohito did not surrender. In response, Truman ordered the dropping of a second bomb called "Fat Man". This bomb hit the city of Nagasaki on August 9, 1945. At least 40,000 Japanese were killed in this attack. Thousands more died in the areas of Hiroshima and Nagasaki in the months and years ahead due to radiation poisoning from the blasts. Japan finally surrendered to the Allies on August 15, 1945. World War II had officially come to an end.
A far-away image of a giant, mushroom-shaped cloud erupting.
Atomic cloud over Hiroshima, photo taken by George R. Caron. By National Archives and Records Administration, public domain
Those who fought in and lived through World War Two saw some of the most horrific tragedies the world had ever seen. This war was unlike any before. Millions of people died in concentration camps fueled by racism and antisemitism. Hundreds of thousands were killed by a new, powerfully lethal atomic bomb. People have long debated if the use of the atomic bomb was the only way to win the war in the Pacific, as Truman's administration claimed.

The political-historical debate

Dr. Peter Zimmerman is an American nuclear physicist. He is also professor emeritus at the Department of War Studies at King's College, London. Zimmerman recently wrote an article titled, "Truman Was Right to Drop the Atomic Bomb." This passage from the article explains his argument:
“Truman’s choice is often framed as ‘the Bomb or the Invasion,’… Not so; the choice was between the bombs, which might force an end to the war in days, and all other scenarios. The other means to an end of the war were cruel. A blockade would starve the country. The Soviet invasion of Manchuria and Korea would result in Stalin’s planned occupation of Hokkaido. U.S. conventional bombing of Japanese cities would continue until the Army Air Forces literally ran out of targets. The rail network used to distribute food would be further wrecked…
What every alternative to the atomic bombing of Hiroshima and Nagasaki has in common is the long time before its effects would crush Japan’s will to continue the battle.
The maritime blockade of the home islands was in effect, and had cut the flow of food from farms in Korea, on Hokkaido, and in Northern Honshu to the Japanese people…
Food shortages were taking effect. When the U.S. occupation began, the Tokyo food ration was down to 900 calories a day, not quite the 600 calorie level in a Nazi concentration camp, but bad enough that the weak and elderly were already dying. Some in the Imperial government had predicted food riots and civil war by December. But not in August, or September.
B-29 bombing raids were destroying one Japanese city every week. Had the war gone on for another month, four or more cities would have been burned to the ground. Roughly one Hiroshima a week. But by August the Japanese population and government had become accustomed to relatively slow destruction; there was time to recover somewhat between raids, to extinguish some fires, evacuate some people, and set up some kind of temporary shelter. This reprieve blunted the shock of the continuing raids.
As July turned to August, the situation required shock therapy. The slow decline of the Japanese fortunes had to be recast by a sudden and catastrophic event. Something was needed to change the perception in Tokyo that fighting on to satisfy some code of honor and loyalty to the emperor was preferable to peace.
The Allies desperately wanted to avoid invading Japan. Our anticipated death toll was north of 100,000 Allied soldiers and sailors…The battle for Okinawa showed the Allies that Japan would struggle until the last civilian was killed” (Zimmerman).
Many disagree with Truman's decision and Zimmerman's explanation. They do not believe that the atomic bomb was less harmful for both Japanese and Allied forces than an invasion. Gar Alperovitz is an American historian and fellow of the Harvard Institute for Politics and King's College Cambridge. He wrote that Truman's main goal in dropping the bombs was to intimidate the Soviet Union. The ambassador to the Soviet Union in 1945 was Joseph E. Davies. He had a meeting with President Truman in May 1945, just two short months before the first successful testing of the atomic bomb. In that meeting, Truman revealed that he would be holding off discussions with Stalin about the post-war world until after the results of the tests were completed. Davies wrote, "I was startled, shocked and amazed" about Truman's decision. In a footnote he wrote, "Uranium—for reason of security I will have to fill this in later" (Alperovitz, 1985).
“On July 16, the first atom bomb was tested successfully at Alamogordo, N.M. On July 17, Truman sat down to talk with Stalin. And on Aug. 6, a bomb would fall on Hiroshima, ultimately killing an estimated 130,000 Japanese and changing the world…
Most Americans assume the reason Hiroshima and Nagasaki were destroyed was simply to prevent a costly invasion of Japan.
However, the newest documents have strengthened the theory that other considerations—especially the new weapon’s impact on diplomacy toward the Soviet Union—were involved.
The invasion of Japan—which President Truman claimed might cost up to a million casualties—was scheduled to begin on Nov. 1…(Documents of the time suggest that many planners foresaw far fewer casualties.)
But by the mid-summer of 1945 Japan was in a very bad way. How allied intelligence understood the situation at the time was detailed in a report to the American and British Combined Chiefs of Staff…
‘The increasing effects of sea blockade and cumulative devastation wrought by strategic bombing…has already rendered millions homeless and has destroyed from 25 percent to 50 percent of the built-up area of Japan’s most important cities…A conditional surrender…might be offered by them at any time…’
Adm. William D. Leahy, who served as chief of staff to the President and presided over the Joint Chiefs of Staff, wrote in his diary in mid-June that ‘at the present time…a surrender of Japan can be arranged with terms that can be accepted by Japan and that will make fully satisfactory provision for America’s defense against future trans-Pacific aggression.’ Afterwards, Leahy would reflect that ‘the use of this barbarous weapon at Hiroshima and Nagasaki was of no material assistance in our war against Japan…’
Likewise, Eisenhower would later state that ‘it wasn’t necessary’ to hit the Japanese ‘with that awful thing’” (Alperovitz, 1985).
There is a third theory as to why the Americans used the atomic bombs on Japan. It also supports the idea that the bombing was used as leverage against the Soviet Union. Professor Tsuyoshi Hasegawa is a Japanese American historian at the University of California, Santa Barbara. He outlines a more complex argument in Racing the Enemy: Stalin, Truman, and the Surrender of Japan (2005). Hasegawa shows how the Soviet Union played both sides to attempt to gain territories in Asia during World War II. He proposes that Japan did not unconditionally surrender because of the American's atomic bombs. He believes they surrendered because the Soviet Union had entered the war against Japan.
“…Stalin was an active participant, not a secondary player, as historians have hitherto depicted, in the drama of Japan’s surrender. He was engaged in skillful Machiavellianstart superscript, 1, end superscript diplomacy to manipulate Japanese desires for negotiated peace to his own ends. He was involved in intense negotiations with the Americans and reacted decisively to American maneuvers. He bullied the Chinese into accepting the Soviet terms, and ruthlessly pursued diplomacy and military operations to secure the territories to which he felt entitled.
The study also casts the Americans use of the atomic bomb in a wider setting. The bomb provided a solution to the previously unsolvable dilemma that faced Truman: to achieve Japan’s unconditional surrender before Soviet entry into the war. Truman issued the Potsdam Proclamation, not as a warning to Japan, but to justify the use of the atomic bomb. I challenge the commonly held view that the atomic bomb provided the immediate and decisive knockout blow to Japan’s will to fight. Indeed, the Soviet entry into the war played a greater role than the atomic bombs in inducing Japan to surrender” (Hasegawa, 5).
In fact, Prince Konoe, admitted that defeat was near as early as February 1945. At the time, Prince Konoe was the Prime Minister of Japan and he made the admission to Emperor Hirohito.
“While the Big Three were meeting at Yalta on February 14, Konoe submitted his memorandum to Hirohito. ‘I regret to say that Japan’s defeat is inevitable,’ the prince began. ‘Defeat will damage the kokutai,squared but public opinion in America and England has not gone far enough to destroy the kokutai…Therefore, we should not be worried about defeat itself. What we must worry about is a Communist revolution that might accompany defeat.’ Konoe then indicated that the Soviet Union would be interested in expanding its influence in Asia, just as it had in eastern Europe. Sooner or later the Soviets would interfere in Japan’s domestic situation…the only way to save the kokutai would be to negotiate with the United States and Britain as soon as possible, an action that would require the direct intervention of the emperor against the military” (37).
The dropping of the atomic bombs certainly sent a clear message to Japan. Americans had new weapons of war that led to horrific consequences. But the Japanese had also become somewhat used to the constant bombings of their cities and military targets. For many Japanese, the atomic bombs were more of a continuation of these bombings. The atomic bombs were not acts that led to the eventual and unconditional surrender of the emperor. On August 8, the Soviets invaded Manchuria. This came just two days after the bombing of Hiroshima. When combined with the bombings and the Soviet declaration of war against Japan, the Japanese knew that they must surrender.

The aftermath

While the justification for dropping the bombs is debatable, the post-1945 world undoubtedly was forever changed. The use of the bombs led to devastation and deaths. But it also led to a race between states to access and improve the technology used to create these nuclear weapons. The U.S. and Soviet Union, in particular, began amassing stockpiles of nuclear weapons during the Cold War. In time, other nations such as the U.K., China, France, and India obtained their own nuclear weapons.
A comparison of Nagasaki before and after the atomic bomb was dropped. The first photo shows a birds-eye view of the city, which was full of buildings, homes, and large roads. The second photo shows the land wiped completely clean of all structures and roads.
Before and after photographs taken at Nagasaki, Japan after the atomic bomb was dropped on August 9, 1945. By U.S. National Archives, public domain.
The fear and horrific effects of nuclear warfare also led to the creation of numerous anti-nuclear groups. These social movements came of age in the 1960s and 1970s. More people demanded to live in a world that had fewer threats to both humans and the environment. One of the largest protests in American political history occurred in 1982 when about one million people marched in New York City to protest nuclear proliferation. Marches, protests, activism, and treaties have continued to impact our nuclear age; however, governments have not always been ready and willing to part with their nuclear weapons.
Author bio
Bridgette Byrd O’Connor holds a DPhil in history from the University of Oxford and has taught Big History, World History, and AP U.S. Government and Politics for the past ten years at the high school level. In addition, she has been a freelance writer and editor for the Big History Project and the Crash Course World History and U.S. History curriculums.

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