The Atomic Bomb and the Collapse of the Grand Alliance

The Manhattan Project (1942–1945) gave the United States the world's first atomic bomb, with the first nuclear test, code-named Trinity, conducted on July 16, 1945, in New Mexico. Weeks later the United States dropped atomic bombs on Hiroshima (August 6) and Nagasaki (August 9, 1945), hastening Japan's surrender, announced on August 15, 1945; estimates place the number of victims at the two cities between 129,000 and more than 200,000 people by the end of 1945. The resulting American nuclear monopoly, which lasted from 1945 to 1949, strengthened Washington's negotiating position vis-à-vis Moscow and gave rise to the concept of "atomic diplomacy," the use of nuclear superiority as political leverage.