Bombing of Nagasaki

The Bombing of Nagasaki on August 9, 1945, was part of the final effort to force Japan’s surrender in the Second World War. The decision to use the atomic bomb had been shaped by military expectations, the rejection of a proposed demonstration, and Harry S. Truman’s awareness that a weapon intended to shorten the war would devastate civilian populations.

Background and the case for use

At Potsdam, senior advisers agreed that the bomb should be used. Truman later recalled asking General Marshall to estimate the cost in American lives of an invasion of the Tokyo plain and other parts of Japan; Marshall estimated at least a quarter of a million American casualties. Truman described reaching his conclusion after long and careful thought, while also recording that he did not like the weapon. The book presents surrender—not simply Japan’s military defeat—as the urgent objective, because continued resistance meant more deaths.

Why a demonstration was rejected

A non-lethal technical demonstration had been considered by the committee advising the president and by its scientific panel. General Marshall had initially proposed using the bomb against a military target, with warnings before any later attack on manufacturing centers. But the advisers concluded that no demonstration could provide a sufficiently powerful shock to induce surrender. Only one bomb might be ready, and if it failed after advance announcement, the attempt could strengthen Japanese resolve instead. The panel therefore found no acceptable alternative to direct military use.

Truman’s reservations and warning

On August 9, Truman wrote that he could not accept answering Japan’s cruelty by acting in the same way. He regretted the prospect of wiping out whole populations because of their leaders’ obstinacy, and said that he would not do so unless it was absolutely necessary. He also believed Japan might soon surrender after the Soviet Union entered the war, while making clear that saving American lives remained his object and that he felt for Japanese women and children. That night, in a radio address about Potsdam, he urged Japanese civilians to leave industrial cities immediately and save themselves.

Consequences and significance

The episode places the bombing within a grave tension in Truman’s reasoning: he regarded the bomb as a means to end the killing and avert the anticipated losses of an invasion, yet recognized the human cost of using it against a country’s population. His August 9 letter and public warning do not remove that contradiction; they make it explicit. The bombing’s significance in the account lies both in its role in the campaign to secure surrender and in the limits Truman said he wished to place on the destruction.