United States conducts first test of the atomic bomb - Jul 16, 1945 - HISTORY.com

The United States conducts the first test of the atomic bomb at at the Trinity bomb site in central New Mexico. The terrifying new weapon would quickly become a focal point in the Cold War between the United States and the Soviet Union.

The official U.S. development of the atomic bomb began with the establishment of the Manhattan Project in August 1942. The project brought together scientists from the United States, Great Britain, and Canada to study the feasibility of building an atomic bomb capable of unimaginable destructive power. The project proceeded with no small degree of urgency, since the American government had been warned that Nazi Germany had also embarked on a program to develop an atomic weapon. By July 1945, a prototype weapon was ready for testing. Although Germany had surrendered months earlier, the war against Japan was still raging. On July 16, the first atomic bomb was detonated in the desert near the Los Alamos research facility. Dr. J. Robert Oppenheimer, director of the project, watched the mushroom cloud rise into the New Mexico sky. “Now I am become death, destroyer of worlds,” he uttered, reciting a passage from an ancient Hindu text. News of the successful test was relayed to President Harry S. Truman, who was meeting with Soviet leader Joseph Stalin in Potsdam to discuss the postwar world. Observers at the meeting noted that the news “tremendously pepped up” the president, and British Prime Minister Winston Churchill believed that Truman almost immediately adopted a more aggressive tone in dealing with Stalin.

Truman and many other U.S. officials hoped that possession of the atomic bomb would be America’s trump card in dealing with the Soviets after the war. Use of the weapon against the Japanese cities of Hiroshima and Nagasaki in August 1945 demonstrated the destructive force of the atomic bomb. The American atomic monopoly did not last long, though. By 1949, the Soviets had developed their own atomic bomb, marking the beginning of the nuclear arms race.