The first atomic bomb was successfully detonated on July 16, 1945, in the Trinity test in New Mexico. Oppenheimer later remarked that it brought to mind words from the Bhagavad Gita: "Now I am become Death, the destroyer of worlds."[2][note 2] In August 1945, the weapons were used in the atomic bombings of Hiroshima and Nagasaki.

The code name "Trinity" was assigned by Robert Oppenheimer, the director of the Los Alamos Laboratory, inspired by the poetry of John Donne. The test was of an implosion-design plutonium device, informally nicknamed "The Gadget", of the same design as the Fat Man bomb later detonated over Nagasaki, Japan, on August 9, 1945. The complexity of the design required a major effort from the Los Alamos Laboratory, and concerns about whether it would work led to a decision to conduct the first nuclear test. The test was planned and directed by Kenneth Bainbridge.