Eighty years ago, on July 16, 1945, the United States successfully exploded the world’s first atomic bomb. Less than a month later, the world witnessed one of its biggest tragedies when two atomic bombs were detonated on Japanese cities, causing absolute devastation and decapitating the Japanese Empire.

Since the August 6 and August 9, 1945, nuclear attack on Hiroshima and Nagasaki, no other country in the world has used an atomic bomb.

However, nuclear proliferation and an unbridled enrichment of uranium by countries considered rogue by the West have captured public imagination. For instance, the US recently went to war against Iran despite domestic opposition and bombed Iran’s nuclear facilities to puncture its nuclear ambitions.

Over the years, several countries have managed to develop and detonate atomic bombs. India was one such country, but was ostracised on the premise that possession of nuclear bombs was dangerous to humanity.

Ironically, the United States has spearheaded the effort that aims to curb nuclear proliferation despite being the only country to have ever used the bomb, causing massive destruction and loss of lives.

The lore of how the United States managed to develop a nuclear bomb in complete secrecy goes back more than eighty years.

The United States officially entered the WW2 in December 1942, following the Japanese attack on Pearl Harbor. The development of an atomic bomb preceded US involvement in the war. However, it was rushed only after the US entered World War II, precipitating the infamous ‘Manhattan Project.’

The Manhattan Project

Before World War II started between the Allies (Great Britain, France, and Poland) and the Axis Powers (Germany, Italy, and Japan), three scientists working in a Berlin laboratory made a discovery in 1938 that would change the course of history: they split a uranium atom and discovered nuclear fission. 

The idea of using fissionable material for military purposes was proposed by Italian emigre physicist Enrico Fermi as early as 1939, when he met US Navy department officials at Columbia University. This meeting essentially laid the groundwork for the Allies to develop a uranium bomb.

Following this, Leo Szilard, a physicist from Hungary, realized that nuclear chain reactions could be used to produce new, incredibly potent atomic weapons. In August 1939, he wrote a letter for Albert Einstein to sign and forward to then-US President Franklin D. Roosevelt, warning that an “extremely powerful bomb” could be constructed using that method.

The discovery in Berlin and information that Nazi Germany was developing an atomic bomb rankled the United States, triggering fears that such a bomb could be used on the Allies.

In response to the threat, Roosevelt established the Advisory Committee on Uranium, which convened for the first time on October 21, 1939. A few months later, in February 1940, the US federal government granted a total of $6,000 for research.

Following Imperial Japan’s bombing of Pearl Harbor on December 7, 1941, the United States formally entered World War II. This prompted the Advisory Committee to contemplate the creation of an atomic weapon that could be manufactured and deployed in time to change the course of the conflict.

This marked the beginning of the Manhattan Project—an unprecedented, classified World War II government program in which the US rushed to develop and deploy the world’s first atomic weapons before Nazi Germany. 

The Army Corps of Engineers created the Manhattan Engineer District in Manhattan, New York, under the command of Brigadier General Leslie Groves, to carry out this mission.

During the early stages of theoretical research, the Manhattan Project would pass through several sites, most notably the University of Chicago, where Enrico Fermi successfully triggered the first fission chain reaction. Following this, the Manhattan Project took shape at three primary locations across the country: Hanford, Washington; Oak Ridge, Tennessee; and Los Alamos, New Mexico.

The Project’s final shape was formed in the New Mexico desert, where J. Robert Oppenheimer, along with other brilliant minds of the time, such as Hans Bethe, Edward Teller, and Fermi, began leading the project.

Finally, under Oppenheimer’s direction, General Groves established a bomb design and development laboratory in Los Alamos, New Mexico, at the beginning of 1943, employing some of the world’s top scientists. 

The facility was situated in a remote region of northern New Mexico, atop the Parajito Plateau. “Here, theory and practice came together, as the problems of achieving critical mass—a nuclear explosion—and the construction of a deliverable bomb were worked out,” as stated by history.com.

The 2023 Hollywood film ‘Oppenheimer’, directed by legendary filmmaker Christopher Nolan and starring Cillian Murphy, explored the theme in detail, adequately recounting the events and the development of the world’s first atomic bomb during a tumultuous time.

The bombs themselves were difficult to build. It took a significant amount of time, experimenting and conducting precise calculations, to achieve the ideal size and shape specifications.

Two designs were pursued: a uranium-based gun-type bomb, “Little Boy,” and a plutonium-based implosion bomb, “Gadget”. A simple gun mechanism was used to create a critical mass and a nuclear explosion in the uranium bomb.

However, scientists deciphered in 1944 that plutonium would not operate as a gun-type weapon and instead turned to the theoretical and extremely complex implosion method.

The first atomic bomb was finally detonated on the morning of July 16, 1945, in the New Mexico desert, 120 miles south of Santa Fe. It came to be known as the Trinity Test.

The Trinity Explosion 

On July 16, 1945, at 5:29:45 a.m., the first atomic bomb, codenamed “Gadget,” was detonated at the Trinity test site in Alamogordo, New Mexico, as part of the Manhattan Project.

This plutonium implosion device was hoisted atop a 100-foot steel tower. It released an explosive yield of approximately 15-25 kilotons of TNT, instantly vaporizing the tower and transforming the surrounding sand into a radioactive, green glass called trinitite.

Under the direction of Groves and headed by J. Robert Oppenheimer, the test verified the feasibility of a plutonium-based weapon, signaling the start of the Atomic Age.

The scientists and a few dignitaries positioned themselves 10,000 yards away to watch as he first mushroom cloud of blazing light stretched 40,000 feet into the air. The fallout covered an area of 1,100 square miles and contaminated regions as far north as Canada.

Now the question was, who would be the target of the bomb? Although the bomb was initially produced to attack Germany, it had already surrendered by this time. So, Japan remained the lone aggressor as it had not surrendered despite intense Allied bombing campaigns, including the firebombing of cities like Tokyo.

The US believed the atomic bombs could deliver a psychological and military shock to compel Japan’s leadership, particularly the militarist faction, to end the war swiftly, avoiding a prolonged conflict. The use of an atomic bomb started gaining traction because an invasion of Japan would result in massive casualties. The bombs were seen as a way to end the war without an invasion.

Moreover, some experts and historians believe that the United States sought to demonstrate the atomic bomb’s unparalleled destructive potential, in part to scare Japan and in part to demonstrate its might to the new adversary, the Soviet Union.

The US hoped to terminate the Pacific theater before Soviet forces, who entered the war against Japan on August 8, 1945, could develop considerable influence in Asia, especially in Manchuria or Japan itself, now that the war in Europe was over.

Japan’s refusal to accept unconditional surrender as per the Potsdam Declaration and its military’s resolve to fight was believed to be the final trigger for dropping the bomb.

The US dropped a uranium gun-type bomb, “Little Boy,” on Hiroshima on August 6, 1945, followed by a plutonium-based implosion-type weapon called “Fat Man” on Nagasaki on August 9, 1945.

The bombings caused explosions, firestorms, and radioactive effects, resulting in massive-scale deaths and destruction. Survivors and their offspring continue to experience long-term health effects, such as cancer and genetic abnormalities.