American scientists, many of them refugees from fascist regimes in Europe, took steps in 1939 to organize a project to exploit the newly recognized fission process for military purposes. In the summer of 1939, Albert Einstein was persuaded by his fellow scientists to use his influence and present the military potential of an uncontrolled fission chain reaction to President Franklin D. Roosevelt. In February 1940, $6,000 was made available to start research. After the U.S. entry into the World war II, the War Department was given joint responsibility for the project. In June 1942 the Corps of Engineers’ Manhattan District was initially assigned management of the construction work (because much of the early research had been performed at Columbia University, in Manhattan). “Manhattan Project” became the code name for research work that would extend across the country.
Only method available for the production of the fissionable material plutonium-239, was developed at the metallurgical laboratory of the University of Chicago. In December 1942, Enrico Fermi, the Italian-born Nobel Prize-winning physicist, finally succeeded in producing and controlling a fission chain reaction in this reactor pile at Chicago. Upon succesful completion of the experiment, a coded message was transmitted to President Roosevelt: “The Italian navigator has landed in the new world.”
The large-scale production reactors were built on an isolated tract on the Columbia River north of Pasco, Washington—the Hanford Engineer Works, for the quantity production of plutonium-239. By the summer of 1945, amounts of plutonium-239 sufficient to produce a nuclear explosion had become available from the Hanford Works, and weapon development and design were sufficiently far advanced so that an actual field test of a nuclear explosive could be scheduled. By this time the original $6,000 authorized for the Manhattan Project had grown to $2 billion. The first atomic bomb was exploded at 5:30 am on July 16, 1945, at a site on the Alamogordo air base 120 miles (193 km) south of Albuquerque, New Mexico, followed by Hiroshima and Nagasaki explosions in the next month.
During World War II, in November 1943, Joseph Stalin, Winston Churchill and Franklin D. Roosevelt met together in Teheran, Iran, to discuss military strategy and post-war Europe, in a conference codenamed Eureka. Ever since the Soviet Union had entered the war, Stalin had been demanding that the Allies open-up a second front in Europe. Stalin, who always favoured in offensive strategy, believed that there were political, as well as military reasons for the Allies’ failure to open up a second front in Europe. Stalin was still highly suspicious of Winston Churchill and Franklin D. Roosevelt and was worried about them signing a peace agreement with Adolf Hitler. The foreign policies of the capitalist countries since the October Revolution had convinced Stalin that their main objective was the destruction of the communist system in the Soviet Union. Stalin was fully aware that if Britain and the USA withdrew from the war, the Red Army would have great difficulty in dealing with Germany on its own.
At Teheran, Joseph Stalin reminded Churchill and Roosevelt of a previous promise of landing troops in Western Europe in 1942. Later they postponed it to the spring of 1943. Stalin complained that it was now November and there was still no sign of an allied invasion of France. After lengthy discussions, it was agreed that the Allies would mount a major offensive in the spring of 1944. Roosevelt and Churchill also accepted Stalin’s demands regarding Poland’s post-war boundaries, which would give the Soviets Lwów, Wilno, and Poland’s eastern Kresy territory occupied by Stalin under his 1939 alliance with Nazi Germany. Churchill proposed that Poland, in return, be compensated with a corresponding slice of Germany. They all agreed that they would continue to make available to the Government of Iran economic assistance as may be possible, having regard to the heavy demands made upon them by their world-wide military operations.
The D-Day landings in June, 1944 took the pressure off the Red Army and from that date they made steady progress into territory held by Germany bringing World war II to end.