The Manhattan Project was a program organized by the U.S. government to build an atomic bomb. The actual bomb was built at the Los Alamos laboratory which was headed by Robert J Oppenheimer. The team included stellar names in physics from across the globe, that ended up in the construction of the two atomic bombs dropped on Hiroshima and Nagasaki. In 1939, Einstein’s letter to President Roosevelt worked to trigger the action, where he suspected that Hitler might be working on the construction of nuclear technology. Initially, the primary goal of the Manhattan Project was research but eventually, it became a race to compete with Germany. On July 16, 1945, the USA was ready with its first atom bomb, called the Gadget. Later, the two atom bombs Little Boy and Fat Man were dropped on Japan, killing lakhs .