The event that led to the detonation of the first atomic bomb was the Manhattan Project, specifically the Trinity Test conducted on July 16, 1945, in New Mexico. This secretive research and development project during World War II successfully created the first nuclear weapon, marking a significant turning point in military technology and warfare. The bomb’s introduction radically altered international relations, initiating the nuclear age and leading to a new dimension in conflicts, particularly evident in the bombings of Hiroshima and Nagasaki shortly after in August 1945.