The 曼哈頓計劃 was a secret research and development project during World War II, aimed at creating the first nuclear weapons. Initiated by the United States with support from the United Kingdom and Canada, it began in 1942 and involved numerous scientists, including notable figures like 羅伯特·奧本海默 and 恩里科·費米. The project culminated in the successful testing of the first atomic bomb on July 16, 1945, in New Mexico, known as the 三位一體試驗. This groundbreaking achievement led to the use of atomic bombs on the Japanese cities of 廣島 and 長崎, significantly impacting the course of the war and global politics.