Atomic bomb

On April 14, 1932, John Cockcroft and E.T.S. Walton of Great Britain successfully split the atom, providing experimental proof for Einstein's Theory of Relativity.

In 1939, Robert Oppenheimer recognizes the potential military applications of nuclear fission, a crucial development in the field of atomic energy.

In September 1939, Albert Einstein contacts President Roosevelt to discuss the use of uranium as a new energy source, leading to the establishment of the Committee on Uranium.

In October 1939, a meeting took place between physicists Einstein and Szilard with President Roosevelt, where they discussed the possibility of Germany developing an atomic bomb. Einstein's letter emphasized the urgency for the U.S. Government to speed up experimental work on powerful bombs.

Plutonium was discovered on February 23, 1941, by Glenn Seaborg, Edwin McMillan, Joseph W. Kennedy, and Arthur Wahl, which played a crucial role in the development of nuclear weapons.

On October 9, 1941, President Franklin D. Roosevelt gave the authorization for the development of an atomic weapon, marking a significant milestone in the Manhattan Project.

On January 19, 1942, President Roosevelt approved the development of an atomic bomb, leading to the establishment of the Metallurgical Laboratory at the University of Chicago under Arthur Compton. This decision had far-reaching consequences for the course of history.

On June 18, 1942, the Army Corps of Engineers formally established the Manhattan District, which played a crucial role in the development of the atomic bomb during the Manhattan Project. This marked a significant milestone in the history of nuclear weapons.

President Franklin D. Roosevelt gives approval for the development of an atomic weapon.

On December 2, 1942, the first controlled nuclear chain reaction took place at the University of Chicago, marking a significant milestone in the development of nuclear technology.

J. Robert Oppenheimer suggests recruiting George Kistiakowsky, the leading explosives research director at The Office of Scientific Research and Development, to aid an expanded implosion effort.

The X-10 Graphite Reactor pile goes critical at Oak Ridge, TN, producing substantial amounts of plutonium for research purposes. Manhattan Project Governing Board approves an ambitious implosion research program.

George Kistiakowsky takes over as the head of implosion research at Los Alamos, replacing Seth Neddermeyer. He becomes a full-time staff member, leading the efforts in developing implosion techniques for the atomic bomb project.

On July 4, 1944, J. Robert Oppenheimer reveals Emilio Segre’s spontaneous fission measurements to the Los Alamos staff. This discovery led to the abandonment of the planned plutonium gun and prioritization of implosion research, marking a significant turning point for the Manhattan Project.

The B Reactor at Hanford Site in Washington state achieves criticality, a crucial step towards full-scale plutonium production for the Manhattan Project's atomic bomb development.

Otto Frisch conducts the Dragon experiment, dropping a U-235 hydride slug through a barely subcritical U-235 hydride assembly, creating the world's first assembly critical through prompt neutrons alone.

In April 1945, the Military Policy Committee of the Manhattan Project designated Japan as the primary target for any future atomic bomb, setting the stage for the devastating events that would follow.

On July 12, 1945, the plutonium core and components of the Gadget, the first atomic bomb, departed from Los Alamos, New Mexico, for the test site separately.

The Gadget, the world's first atomic test device, was successfully detonated on July 16, 1945, at the Trinity Site in New Mexico, marking a significant milestone in the development of nuclear weapons.

The world's first atomic detonation occurred in the Trinity Test at Alamogordo, New Mexico.

President Truman gave the order for the use of atomic bombs.

On August 6, 1945, the United States dropped an atomic bomb on Hiroshima, leading to widespread destruction and loss of life, marking a turning point in World War II.

Three days after the bombing of Hiroshima, on August 9, 1945, the United States dropped a second atomic bomb on Nagasaki, further devastating the city and hastening Japan's surrender.

The United States distributes warning leaflets in Nagasaki regarding the potential of another atomic bomb being dropped, a day after the devastating atomic bomb was actually detonated in the city.

The UN General Assembly passes its first resolution urging for the total eradication of nuclear weapons and establishes a commission to tackle the issue.

The U.S. conducted its first postwar nuclear test, Operation Crossroads, at Bikini Atoll to study the impact of nuclear weapons on naval warships.

The U.S. military detonated a 23 kiloton atomic bomb underwater at Bikini Atoll as part of Operation Crossroads, causing severe contamination to naval vessels.

On December 25, 1946, Soviet scientists achieved a nuclear chain reaction, marking one of the initial steps in building the atomic bomb.

On January 1, 1947, the Atomic Energy Commission assumed control of the Manhattan Engineer District, which was responsible for the development of the atomic bomb during World War II.

On August 25, 1947, the Manhattan Engineer District was officially abolished, marking the formal end of the Manhattan Project, which was a significant scientific and military undertaking during World War II.

The U.S. military conducted the first fission weapon test using a levitated core design in Operation Sandstone.

The Soviet Union conducts a successful test of its inaugural nuclear weapon named 'First Lightning' in Semipalatinsk, Kazakhstan, marking its entry as the second nation to possess and test a nuclear bomb.

The US military conducts the Dog Shot of Operation Buster, a 21 kiloton airdrop fission bomb with a composite plutonium-uranium core as part of Operation Desert Rock I.

The United States conducts the “Sugar” nuclear test on November 19, 1951 at the Nevada Test Site, yielding 1.2 kilotons, as part of Operation Buster-Jangle and Operation Desert Rock II.

On May 9, 1952, the U.S. conducted the 'George' test in the Pacific, which involved a large fission bomb triggering the first thermonuclear reaction.

In September 17, 1952, U.S. physicist Marshall Holloway was named the leader of the H-bomb project, while Edward Teller left Los Alamos shortly afterwards.

The United States tests its first ever thermonuclear device, the Mike Shot, on November 1, 1952, at Eniwetok Atoll, yielding 10 megatons of TNT.

The United States detonates a 17-megaton hydrogen bomb, known as "Bravo", at Bikini Atoll in the Pacific Ocean. This event resulted in the contamination of a Japanese fishing boat, Lucky Dragon, and affected residents of Rongelap and Utirik.

The Soviet Union detonates the most powerful bomb ever, the Tsar Bomba, with a yield of 58 megatons over Novaya Zemlya in northern Russia.

On October 10, 1963, the Limited Nuclear Test Ban Treaty, which prohibits nuclear weapon tests in the atmosphere, outer space, and underwater, goes into effect.

China successfully detonates its first atomic bomb at the Lop Nor testing site in Xinjiang Province. This marks China's entry into the nuclear arms race.