The Manhattan Project was a secret research and development program 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 some of the greatest scientific minds of the time, including J. Robert Oppenheimer and Enrico Fermi. The project culminated in the successful testing of the first atomic bomb on July 16, 1945, in New Mexico, known as the Trinity Test. This groundbreaking achievement led to the eventual use of atomic bombs on the Japanese cities of Hiroshima and Nagasaki in August 1945, significantly impacting the outcome of the war.