The Kennesaw State University Department of Museums, Archives and Rare Books (MARB) presents exhibitions, public programs, collections, and educational services supporting KSU’s mission and encouraging dialogue about the past and its significance today. The Museum of History and Holocaust Education, as a unit of MARB, has developed a series of online modules, including this one, for university students to explore pivotal moments from the history of World War II and the Holocaust.
This online unit focuses on the history of the Manhattan Project along with its contributions and consequences. The project itself was extensive and composed of many individuals from the scientists who made innovations to the construction workers who built the facilities from the ground up. Highlighting a diversity of sources, this unit tells the story of the making of the first atomic weapons and their use against Japan by discussing the lives of those involved and the science behind the weapons.
Title Image: The Oak Ridge Y-12 Plant, Oak Ridge, Tennessee, ca. 1976. Courtesy U.S. Department of Energy
Image: X-Alpha with Magnetic Field Tester at Oak Ridge, 1943. Courtesy National Archives
Essential Questions
Using the primary source material and content in this online unit, respond to the three essential questions found below. In your responses, include evidence from the content in this online unit. Please refer to the directions provided by your instructor on submitting your responses to these essential questions as well as to the questions posed throughout this unit.
- How did scientific innovations made during the Manhattan Project impact U.S. society as a whole?
- How did being employed on the Manhattan Project affect workers?
- What are the legacies and consequences of the Manhattan Project, and how are we still affected by the project today?
Image: Indiana Cyclotron with Larry Langer and Franz N.D. Curies, 1940. Courtesy National Archives
The Beginnings of Atomic Weaponry
In 1938 Germany, Lise Meitner, Otto Hahn, and Fritz Strassmann experimented with atoms by bombarding different elements with neutrons. With these experiments, they discovered uranium atoms could turn into different isotopes when bombarded, a process they did not understand, at first. They concluded that they had done what was previously thought impossible; they had split an atom. This discovery of nuclear fission would soon become public knowledge. Their findings were presented at a physics conference in the United States in January 1939. Other scientists across the globe quickly confirmed that the fission of uranium's 235 isotope released further neutrons and created a chain reaction. With this revolutionary discovery, Meitner, Hahn, and Strassmann helped usher in the start of the nuclear age.
Image: Lise Mietner and Otto Hahn, ca. 1930s. Courtesy The Conversation
Einstein and Szilard's Roles in Developing the Bomb
After Meitner, Hahn, and Strassmann revealed their findings, many scientists began theorizing about the production of a chain reaction as a result of nuclear fission. They believed this chain reaction could produce enough energy to create a mass explosion. Fearful of the idea that Germany could actively be trying to create an atomic weapon, in 1939, Albert Einstein and Leo Szilard drafted a letter to President Roosevelt, encouraging him to create a program dedicated to this research and to keep a watchful eye on atomic developments in Germany.
Click the button below to read the Einstein-Szilard Letter:
As you read, consider the following questions:
- What does this letter reveal about the importance of the discovery of nuclear fission?
- How did nuclear fission impact the scientific community?
Image: Leo Szilard with Albert Einstein writing letter to President Roosevelt- Re-Enactment, 1948. Courtesy UC San Diego Digital Collections
Roosevelt's Response
In October 1939, President Roosevelt formed the Uranium Committee to begin small-scale research on atomic explosions. Funding for the committee increased as scientists around the world published additional findings about the possible construction of an atomic weapon. This included two documents, the Frisch-Peierls Memorandum, which discussed the possibility of atomic explosives, and the MAUD Committee report, which theorized how an atomic bomb could be made. These documents influenced FDR's decision to turn atomic research over to the Army and create the Manhattan Project in 1942.
Click the buttons below to read the two following documents:
As you read, consider the following question: How did these documents contribute to the formation of the Manhattan Project?
Image: President Franklin D. Roosevelt Signing the Declaration of War Against Japan, 1941. Courtesy National Archives
Creating the Manhattan Project
The Manhattan Project was a massive endeavour which, at its peak, employed around 125,000 individuals and cost nearly $2 billion (approximately $30 billion today). General Leslie Groves was chosen to command and oversee the Manhattan Project. Later, Groves selected J. Robert Oppenheimer to act as director for the scientific research laboratory in Los Alamos, New Mexico. Although many questioned how the eccentric Oppenheimer and the stoic Groves could work together, they got along well. Their solid partnership in the project was essential to the creation of the atomic weapon.
Click the button below to learn more about the partnership between Groves and Oppenheimer:
Examine the material below to dive deeper into the personalities of Groves and Oppenheimer:
As you read and watch, consider the following questions:
- What does the interview show us about Oppenheimer’s personality?
- What does the document show about General Groves’ position on the use of atomic weapons?
- Based on the material above, why did many believe Oppenheimer and Grove would not get along? Why do you think they ultimately had such a strong partnership?
Image: Oppenheimer and Groves at Ground Zero, 1945. Courtesy U.S. Department of Energy
Universities and the Atomic Weapon
Universities across the United States were already conducting atomic research in the 1930s, so Oppenheimer recruited most scientists from these institutions. The project had informal beginnings in the university laboratories, and these labs were integral in starting research into the project, conducting experiments related to atomic explosives, and solving problems experienced at other sites of the project later. The main universities that worked on the project included: Berkeley (the Rad Lab), Columbia University, and the University of Chicago (the Chicago Met Lab). The three were collectively known as the Metallurgical Project.
Image: Reunion of atomic scientists on the 4th Anniversary of the first controlled nuclear fission chain reaction, 1946. Courtesy University of Chicago Library
Oak Ridge, Tennessee
The Manhattan Project included three major sites each focusing on a different aspect of the project. Oak Ridge focused on the production and enrichment of uranium. Three plants at Oak Ridge were created over a period of three years. At first, these different plants were constructed to determine which method was best for enriching uranium, but eventually, all three were used in conjunction.
The three plants were given the code names Y-12, K-25, and S-50. The Y-12 plant used electromagnetic separation, the K-25 plant used gaseous diffusion, and finally, the S-50 plant used liquid thermal diffusion for enrichment.
Image: K-25 Gaseous Diffusion Process Building at Oak Ridge, ca. 1940s. Courtesy Atomic Archive
Los Alamos, New Mexico
The Los Alamos site was the official laboratory for the Manhattan Project and worked on the physical creation and research of atomic bombs. The site, also known as Project Y, was largely staffed by scientists trying to make an atomic weapon as fast as possible. Housing and other amenities on site continued to expand throughout the Manhattan Project to meet the needs of those working on the bomb and their families.
Image: Town site at Los Alamos, ca. 1940s. Courtesy Atomic Heritage Foundation
Hanford, Washington
Many in the project feared that they would not be able to produce enough enriched uranium before the Axis Powers developed their own atomic bomb. As a result, Groves created the Hanford site which focused on the production of the man-made element, plutonium, to use in atomic bombs. This site largely used the B-Reactor plant, the first full-scale plutonium production reactor.
Image: B Reactor at Hanford, ca. 1940s. Courtesy Atomic Archive
Life in the Manhattan Project
Most of those working on the Project at Oak Ridge, Los Alamos, and Hanford lived on site, often with their families. Many workers were enticed by the wages and access to housing and food post-Great Depression. Experiences living on site differed among workers. Generally, the sites were laid out like towns and included schools, shopping centers, and recreation facilities. Groves felt that it was important to create a sense of community for the workers and their families considering the secrecy and isolation that was often required of those employed.
Click the button below to read about mail censorship at Los Alamos:
As you read, consider the following question: In what ways were normal aspects of life affected by the secrecy of the Manhattan Project for workers on site?
Those working on the Manhattan Project, their families, and the surrounding communities also faced dangers and health risks as radiation contaminated each site's water, soil, produce, farm animals, and air. Workers were kept in the dark about these dangers and many suffered life-long health issues related to radiation exposure.
Image: Interior of Fuller Lodge, ca. 1940s. Courtesy of Atomic Heritage Foundation
Individual Experiences in the Manhattan Project
Click the buttons below to learn more about specific experiences at the different sites.
After reading and watching, consider the following questions:
- How were the different experiences unique, and how were they similar?
- How did race, class, and gender affect daily life?
Image: Lunch Break at Oak Ridge, ca. 1940s. Courtesy U.S. Department of Energy
Who Worked on the Project?
It is estimated that the Manhattan Project hired up to 600,000 people total throughout its cultivation. Perhaps the most well known individuals who worked on the Manhattan Project were the scientists who aided in developing the atomic bomb. Many scientists who worked on the project were refugees who had escaped the war and Nazi Germany. Due to the classified nature of the project, scientists were often recruited individually and in secret.
Image: Leaders of the S-1 project, consider the feasibility of the 184-inch cyclotron at Berkeley, 1940. Courtesy U.S. Department of Energy
Who Built and Maintained Sites?
There were also many others who contributed to the project that were not scientists. Construction workers, laborers, and mechanics all worked on the Manhattan Project, and were especially important in building sites, as well as the bombs themselves. Furthermore, custodial staff, domestic workers, and administrative workers were integral in maintaining a clean and efficient environment.
Image: Hanford, Washington, workers sending money home, ca. 1940s. Courtesy Atomic Archive
How Was the Military Involved?
Many men and women who were in the military worked on the project, as well. Some of these groups included the Women's Army Corps (WAC), the Provisional Engineer Detachment (PED), and the Special Engineer Detachment (SED).
Members of the WAC largely assisted with clerical and administrative duties which could range from nursing to working as a secretary.
Members of the PED worked largely on service jobs centered around mechanical and technical work.
Members of the SED were highly skilled mechanics and technicians who were tasked with solving many of the engineering problems that scientists confronted during the project.
Image: A WAC detachment marching at Oak Ridge, 1945. Courtesy Atomic Archive
Hidden Faces of the Manhattan Project
The Manhattan Project had a more diverse work force than is often assumed. Many members of marginalized groups worked on the project and contributed to its success.
African Americans filled a variety of roles, and these roles were dependent on the site. Most African Americans worked at Hanford and Oak Ridge as construction workers, custodial workers, and domestic workers. Black scientists also worked on the project but only at universities including Columbia University and the Chicago Met Lab.
While the Manhattan Project presented African Americans with unprecedented opportunities to earn higher wages, they were still negatively impacted by racism and segregation within the sites. Oak Ridge and Hanford were both segregated with Black workers living in worse conditions than white employees. They often experienced further discrimination from businesses and law enforcement as well.
Click the button below to read about many of the Black scientists who contributed to the Manhattan Project:
As you read, consider the following question: In what ways did Black scientists play a role in the success of the Manhattan Project?
Image: African American construction workers at Hanford, ca. 1940s. Courtesy Atomic Heritage Foundation
Women in the Manhattan Project
Women played integral roles in the Manhattan Project. This included a variety of positions, such as technicians, scientists, or secretaries. Many of the women who worked as secretaries and clerks held major administrative responsibilities and had a high security clearance. Women also made up most of the domestic services including education, nursing, or maid services. Higher positions of employment, however, were largely or exclusively held by white women.
Women who lived on site, but were not employed by the project, still played vital roles. These women were often wives and mothers who contributed by supporting husbands who worked on the project and raising families, adding to the sense of community that Groves sought to create.
Image: Women going to work at the Y-12 plant at Oak Ridge, ca. 1940s. Courtesy Atomic Heritage Foundation
Hispanos at Los Alamos
Hispanos made up a significant portion of the workforce at Los Alamos. Hispano men were usually employed as construction workers or in custodial duties while women were often domestic workers or technicians. Hispanos reported mixed experiences as employees of the Manhattan Project. While many describe friendly relations, others still experienced discrimination. Even so, many Hispanos were content with the opportunities Los Alamos gave them.
Image: Hispano Women at Los Alamos, ca. 1940s. Courtesy The New Mexican
Pueblos at Los Alamos
Most Native Americans who worked on the project were located in Los Alamos and were part of the Pueblo tribe. Pueblo men worked in construction, maintenance, carpentry, and other service duties. Like Hispano women, Pueblo women were usually domestic workers. Many of those who lived in Los Alamos were interested in the art, literature, and culture of the Pueblo people. In particular, Los Alamos residents supported Pueblo artists by buying pottery. Despite some interest in Pueblo art and culture, overall Pueblos experienced discrimination and prejudice, similar to Hispanos.
There are very few reports of other Native Americans who worked on the project, and the only known Native scientist was Herbert York who worked at the Oak Ridge plant.
Click the button below to read about Herbert York:
As you read, consider the following question: What contributions did York make to the project?
Image: Maria Montoya Martinez and her grandchild with Enrico Fermi, ca. 1940s. Courtesy Atomic Heritage Foundation
Displaced Tribes
While there were Indigenous people who worked on the project, there were also tribes who were hurt by it. The Umatilla, Yakima, and Nez Perce tribes were all displaced when the Hanford site was built. The tribes were forced to leave sacred land that was integral to their culture and livelihoods. While the Hanford plant allowed supervised visits to the land during the project, the tribes still do not have authority over that land today. Additionally, the tribes still deal with negative health and environmental ramifications from exposure to radioactive material.
Hanford was not the only site to displace Indigenous tribes. In fact, following World War II, nuclear testing in New Mexico and Nevada continued to displace Native people.
Image: Wanapum Tule in Washington. Courtesy Atomic Heritage Foundation
Navajos and Uranium Mining
The Navajo were also adversely affected by U.S. atomic endeavors. Starting in the early 1940s, many Navajo were employed to mine Uranium with little to no protection despite documented knowledge that exposure to radiation had harmful effects. Despite the eventual closing of approximately 500 uranium mines, decades of exposure and contamination continue to have ramifications for the Navajo today.
Image: Navajo miners work at the Kerr-McGee uranium mine, 1953. Courtesy NPR
The Making of the Atomic Bomb
Many early breakthroughs were necessary for the creation of the bomb. One of these was the Chicago Pile-1 at the Chicago Met Lab, which tackled the problem of creating a self-sustaining nuclear reaction. The experiments were successful, and the Chicago Pile-1 served as a model for plutonium production. These breakthroughs often happened at Columbia, Berkeley, and the Met Lab and were transferred to the different plants on a much larger scale.
Image: One of at least twenty-nine similar uranium-graphite lattice structures at the Chicago Met Lab. Courtesy U.S. Department of Energy
Issues with Plutonium and Uranium
Because of the pressure to produce an atomic weapon as fast as possible, many problems arose with a need for quick and efficient solutions. Oftentimes, however, solutions only created new problems. For instance, although the development of plutonium addressed shortages of enriched uranium, its unstable nature presented the risk of early detonation. The discovery of plutonium’s instability was crucial in helping scientists design how the bombs would be made.
Furthermore, problems with machines were constant. Because they were built incredibly fast and often without significant testing beforehand, the use of machines went through a trial and error process with consistent need for maintenance.
Image: y-12 Alpha Racetrack at Oak Ridge, ca. 1940s. Courtesy Atomic Archive
Little Boy and Fat Man
The United States developed two bombs and a test bomb. The uranium bomb, nicknamed “Little Boy,” was made with a gun design where one mass of uranium was fired at another mass of uranium. This created a chain reaction and, subsequently, an explosion. The plutonium bomb, nicknamed “Fat Man,” was created with the use of an implosion design. This type of design used explosive charges which compressed a mass of plutonium until it imploded.
The Trinity Test, done in July 1945, tested the plutonium bomb. There was not a test bomb for the uranium atomic weapon because there was not enough uranium to create one. The Trinity Test was considered a success and “Little Boy” was used less than a month later in Hiroshima.
View footage of the Trinity Test below:
As you watch, consider the following question: Why was it so important that the Trinity test went well?
Image: Fat Man being lowered and checked on transport dolly for airfield trip, ca. 1940s. Courtesy Atomic Heritage Foundation
To Drop or Not to Drop
When President Roosevelt died in April 1945 and former Vice President Harry Truman took his place, he was given information about the possible use of atomic weapons to end the war. The Japanese Imperial Army was planning on continuing to fight despite knowing the dire nature of the situation. Documents later made public revealed that Japan had planned an extremely costly resistance hoping the United States would eventually call for a cease fire. When Japan refused to surrender, President Truman had one of many choices to make. Examine the list below for four of his potential options:
- Continue conventional bombings
- Perform a ground invasion
- Demonstrate the atomic weapon in an unpopulated area
- Drop the atomic bomb on civilians
While scientists who worked on the Manhattan Project began a petition encouraging the President to demonstrate the atomic weapon instead of using it against a populated city, this was largely drowned out by military concerns.
Click the button below to read the scientists' petition to Truman:
As you read, consider the following question: What was the position of scientists on dropping the bomb and why?
Image: Aerial view of Hiroshima before the bombing. Courtesy The Atlantic
Truman's Decision
Ultimately, President Truman decided to use the weapons on Hiroshima (August 6) and Nagasaki (August 9), bringing forth the surrender of Japan. Truman and his advisors justified their decision by arguing that millions of American lives would have been lost during a land invasion of Japan. While private documents revealed President Truman regretted the loss of life, he stood by his decision saying he would do it again if in the same position.
Click the button below to read correspondences from Harry Truman:
As you read, consider the following questions:
- What do these correspondences reveal about President Truman’s view of the Japanese as a whole?
- How do you think this view affected his decision to drop the bombs?
Image: Senator Harry S. Truman in his office in Washington, D.C., 1942. Courtesy Harry S. Truman Library and Museum
Before Truman made the final decision to drop an atomic bomb on Hiroshima, he warned the Japanese in a widely broadcasted speech to surrender or be subject to an attack unprecedented in human history. When the Japanese refused to surrender, he continued with the plan to attack Hiroshima and made another speech to publicly announce the attack as well as the invention of a new type of weaponry.
Watch the two videos below and consider the following questions:
- Do you think Truman’s warning accurately conveyed the destruction an atomic bomb would bring?
- What do these two pieces of footage reveal about Truman’s position on the scientific achievement of the atomic bomb?
Dropping the Bombs
Before the bombing of Hiroshima, a new unit, known as the 509th Composite Unit, began training in Utah by dropping 100 lb dummy bombs. Colonel Paul Tibbits commanded the group, and in June 1945 Tibbits and his crew traveled to Tinian Island to prepare for an attack on Japan. On August 6th, 1945, the Uranium bomb, Little Boy, was dropped on Hiroshima using the plane, Enola Gay.
Image: The ground crew of B-29 "Enola Gay", ca. 1940s. Courtesy Whiteman Air Force Base
Hiroshima
When the bomb was dropped, 90% of Hiroshima was immediately destroyed with anyone in a two-mile radius incinerated. Temperatures in the immediate area reached over 5,000 degrees Fahrenheit. Many survivors suffered from fatal or near-fatal burns, radiation poisoning, and lost limbs. At least 80,000 were killed in the initial blast with at least 60,000 more dying in the months afterwards due to the effects of the bomb.
Image: Aftermath of Hiroshima, 1945. Courtesy New York Times
Nagasaki
Despite the tragedy in Hiroshima, Japan was not ready to surrender. This prompted President Truman to drop a second bomb on Nagasaki with Fat Man. The second bombing killed at least 40,000 total, but some estimates push this number closer to 80,000.
Click the button below to read stories of the survivors:
As you read, consider the following questions:
- What do these stories reveal about the long-term trauma, health problems, and social issues associated with atomic bombings?
- Why is it important to give survivors of Hiroshima and Nagasaki a voice when discussing the Manhattan Project?
Image: Mushroom Cloud over Nagasaki, 1945. Courtesy Atomic Archive
Espionage
Espionage was a major fear for General Groves and many others working on the project. The Alsos Mission as well as the Venona Project worked to uncover German intelligence on atomic weapons and any attempts of espionage during the Manhattan Project. Through the Venona Project, the United States was able to uncover coded messages being sent to the Soviet Union, which were eventually decrypted in 1946, after the project was completed. Much to the United States’ surprise, the Soviet Union had spies in almost every branch of government along with the Manhattan Project.
Image: Alsos members Goudsmit, Wardenburg, Welsh, and Cecil. Courtesy Atomic Heritage Foundation
The Rosenberg Trials
One of the most famous instances of Soviet espionage was the case of David Greenglass who was revealed to be a Soviet spy collecting information about the Manhattan Project. This information led to the controversial Rosenberg Trials which sentenced Ethel and Julius Rosenburg to death for their work as leaders in a spy ring. The case remains controversial because of Greenglass’s testimony. While he originally testified that he never spoke to his sister, Ethel Rosenberg, about espionage, he later re-testified that Ethel was actually the one to type the messages. This testimony was given in exchange for a deal that Greenglass’s wife could stay home with their children while he served his sentence. Greenglass later stated in an interview that he believed that his wife was actually the one to type the messages, but his wife was more important to him than his sister.
Image: Julius and Ethel leaving court after being found guilty, 1951. Courtesy Atomic Heritage Foundation
Legacy and Consequences
The legacy of the Manhattan Project is a controversial one. The Project led to unprecedented scientific breakthroughs and vast, diverse opportunities for the 600,000 who were employed on the Project. It also ended in great tragedy, however, with the bombings of Hiroshima and Nagasaki and inflicted harm on Native American communities. Realizing these complexities allows us to understand the Project, and its implications, in a more holistic way.
Additionally, the Manhattan Project opened the door for the development of atomic weaponry. As World War II came to an end and tensions between the United States and the Soviet Union worsened, the threat of ever more powerful atomic weapons played an important role in the arms race of the Cold War. The use of atomic weapons as well as the use of nuclear energy is still an important discussion and cause for fear across the world today.
Click the buttons below to view virtual tours of Manhattan Project sites and a documentary about the Manhattan Project:
Image: Little Boy ready to be lifted into the Enola Gay, 1945. Courtesy Atomic Heritage Foundation
EnGage
Meet History Face to Face
The Manhattan Project was made up of a diverse group of individuals who each contributed in various ways.
Click the buttons below to explore the stories of individuals involved in the Manhattan Project. Select two of the three interviews and respond to the accompanying writing prompt according to the directions provided by your instructor.
Write: Analyze the role of individuals in the completion of the Manhattan Project as well as the impact of the Project on the lives of individuals. In your response, consider the following questions:
- What role did this person play in the project?
- How did gender, race, and/or class impact each individual's experience?
- Why did they choose to work on the Project?
- How did they view the bombings of Hiroshima and Nagasaki?
- What lasting impact did the Project have on their life?
Image: Hispano workers at Los Alamos, ca. 1940s. Courtesy The New Mexican
Thank you for participating in our online unit, "The Manhattan Project." If you would like to learn more about the many resources the Department of Museums, Archives, and Rare Books at Kennesaw State University offers, please follow the link below:
Image: Courtesy the Museum of History and Holocaust Education at Kennesaw State University
This digital lesson was curated and designed by Sophia Dodd from the University of Georgia in collaboration with staff from the Museum of History and Holocaust Education at Kennesaw State University.