The United States orchestrated the world’s first nuclear explosion on 16 July 1945.
Most of the weapons-grade uranium generated by the Manhattan Project had been incorporated into a bomb (Little Boy). Also on the 16th, the USS Indianapolis left Mare Island Naval Shipyard in California “on a secret mission to deliver [those] atomic bomb components to Tinian Island in the Marianas.” Two days earlier, 14 July 1945, Little Boy had started on “its trip westward to the Pacific without its design having ever been fully tested.”
The test took place 210 miles south of Los Alamos in “a remote corner on the Alamagordo (ahl-ah-moh-GOHR’-doh) Bombing Range known as the Jornada del Muerto (Journey of Death). Robert Oppenheimer had code named the test “Trinity.”
Hoisted atop a 100-foot tower, a plutonium device, called “Gadget,” detonated at precisely 5:30 am over the New Mexico desert, releasing 18.6 kilotons of power, instantly vaporizing the tower and turning the surrounding asphalt and sand into green glass, called “trinitite.” Seconds after the explosion, an enormous blast sent searing heat across the desert, knocking observers to the ground.
Project leader Oppenheimer (father of the atomic bomb) described the moment:
I remembered the line from the Hindu scripture the Bhagavad-Gita. “Now I am become Death, the destroyer of worlds.” I suppose we all thought that, one way or another.
According to Manhattan Project records:
Oppenheimer himself had bet ten dollars against George Kistiakowsky’s entire month’s pay that the bomb would not work at all… The blast wave knocked Kistiakowsky (who was over five miles away) to the ground. He quickly scrambled to his feet and slapped Oppenheimer on the back, saying, “Oppie, you owe me ten dollars.”
Soon shock and euphoria gave way to more sober reflections. Rabi reported that after the initial euphoria, a chill soon set in on those present. The test director, Kenneth Bainbridge, called the explosion a “foul and awesome display” and remarked to Oppenheimer, “Now we are all sons of bitches.” Expressions of horror and remorse are especially common in the later writings of those who were present. Oppenheimer wrote that the experience called to his mind the legend of Prometheus, punished by Zeus for giving man fire, and said also that he thought fleetingly of Alfred Nobel’s vain hope that dynamite would end wars. Most famously, Oppenheimer later recalled that the explosion had reminded him of a line from the Hindu holy text, the Bhagavad-Gita: “Now I am become Death, the destroyer of worlds.”
In 1939, Italian emigre physicist Enrico Fermi “met with U.S. Navy department officials at Columbia University to discuss the use of fissionable materials for military purposes.” Research began the following year with a modest budget of $6,000 (about $128,000 in 2022 dollars).
In 1942, with the United States involved in the war, the US Army began working on a nuclear weapon with an unlimited budget.
The Manhattan Project (so-called because of where the research began) would wind its way through many locations during the early period of theoretical exploration, most importantly, the University of Chicago, where Enrico Fermi successfully set off the first fission chain reaction. But the Project took final form in the desert of New Mexico, where, in 1943, Robert J. Oppenheimer began directing Project Y at a laboratory at Los Alamos.
Scientists were racing against fears that Nazi Germany was also developing an atomic bomb.
On 06 August 1945, the United States dropped Little Boy on Hiroshima, Japan. We killed about 80,000 people. Civilians.
The uranium bomb destroyed an area approximately 5 square miles; less than 10 percent of the buildings were unscathed. Almost everything within one mile of ground zero was destroyed; the “blast wave shattered glass in suburbs” 12 miles away. The aircraft that dropped the bomb, the Enola Gay, felt the blast despite being 11.5 miles away. The estimated yield was 15 kilotons (15,000 tons of TNT).
By the end of 1945, about 100,000 had died. The five-year death total may have exceeded 200,000.
The plutonium implosion bomb was 40 percent greater in strength than Little Boy. Almost everything up to half a mile from ground zero was completely destroyed; it affected an area of approximately 43 square miles. By the end of 1945, about 70,000 had died.
The emperor of Japan forced the military to surrender.
The enemy has begun to employ a new and most cruel bomb, the power of which to do damage is, indeed, incalculable, taking the toll of many innocent lives. Should we continue to fight, it would not only result in an ultimate collapse and obliteration of the Japanese nation, but also it would lead to the total extinction of human civilization (emphasis added).
On 15 August 1945, Emperor Hirohito surrendered to the United States and the Allies in a four-minute radio address (Gyokuon-hoso or “Jewel Voice Broadcast”).
The speech was a watershed moment in modern Japanese history. It was the first time the emperor had spoken to the “common people” of Japan and the first time they had ever heard the sound of his voice. His announcement ended the war, set the nation on another course of transformation some 87 years after the beginning of the Meiji era, and sealed the end of imperial Japan.