The bombing of Nagasaki on August 9th was the last major act of World War Two and within days the Japanese had surrendered. The devastation wrought at Hiroshima was not sufficient to convince the Japanese War Council to accept the Potsdam Conference’s demand for unconditional surrender.
Two senior American military figures – General Groves and Admiral Purnell – were convinced that two atomic bombs dropped within days of the other would have such an overwhelming impact on the Japanese government that it would surrender. Scientists at Los Alamos were also intrigued as to which type of bomb was the better – a uranium or plutonium based bomb. ‘Little Boy’ showed its effectiveness at Hiroshima but another bombing mission was needed to see what damage a uranium bomb could do.
‘Bockscar’ carried an atomic bomb that differed from ‘Little Boy’ carried by ‘Enola Gay‘ for the Hiroshimabombing. ‘Fat Man’ was not a gun-type bomb but used the implosion method; it had a circle of 64 detonators that would drive pieces of plutonium together into a supercritical mass. ‘Little Boy’ had used Uranium 235. ‘Fat Man’ weighed about 10,000 lbs and was 10 feet 8 inches long. It had the explosive capacity of about 20,000 tons of high explosives.