It was not necessary to use atomic weapons on a population centre  The first bomb, on Hiroshima was sufficient to achieve the objective of surrender without the use of the second bomb after only a very short period of time. There was only three days between the two bombings, an unpardonably short period. Communications between Hiroshima and Tokyo had unsurprisingly been severed, so the full effect had yet to sink in on some policy makers by the time ‘Fat Man’ was dropped. It had however already convinced Foreign Minister Togo, Prime Minister Suzuki and crucially the Emperor himself. He said upon hearing the news of Hiroshima: “Now that things have come to this impasse, we must bow to the inevitable. ... We should lose no time in ending the war so as not to have another tragedy like this.” [1] The rest of the cabinet was as yet unmoved, but even if they had been it is unlikely they would have been able to actually surrender before the second bomb was dropped.  There were significant other factors in play as well. Before the second bomb was dropped the Japanese had learnt of the Soviet attack which dashed their last hopes of mediation for a favourable settlement and they were not optimistic of their chances in that conflict, even the army’s planners expected Manchukuo’s capital Changchun would fall in two weeks. [2] Although the Cabinet was deadlocked 3 to 3 this was the case both before and after the news of Nagasaki came in, the point of fact that the US had more than one bomb although a shock to those opposed to surrender did not alter their position. Ultimately the Emperor was forced to intervene on the side of the proponents of peace, his mind had been made up even before the first bomb. It is arguable that Hiroshima was necessary to push him into acting, which was unprecedented but the Nagasaki bombing was entirely superfluous. Historian Sadao Asada’s opinion is that the second bomb was unnecessary. [3]  [1] Emperor Hirohito quoted by Sadao Asada, ‘The Shock of the Atomic Bomb and Japan’s Decision to Surrender - A Reconsideration’ in Hiroshima in History: The Myths of Revisionism p.33.  [2] Sadao Asada, ‘The Shock of the Atomic Bomb and Japan’s Decision to Surrender - A Reconsideration’ in Hiroshima in History: The Myths of Revisionism, p.36.  [3] Sadao Asada, ‘The Shock of the Atomic Bomb and Japan’s Decision to Surrender - A Reconsideration’ in Hiroshima in History: The Myths of Revisionism, pp.38, 41-2.