By the summer of 1945, it was clear that Japan was nearing defeat.  The only question remaining was how that final defeat would come.  A few American statesmen believed that a negotiated end was possible; some Japanese officials had suggested that Sweden might serve as a mediator. But most had little confidence in this route.  For America’s military leaders, it was largely irrelevant—their task was to find the military solution to the war.   

Every branch had its proposal.  The navy believed that a blockade would cripple the already struggling Japanese economy.  The air force pointed out that it was already bombing at will. The army stated that it was prepared for a land invasion of the islands.  Yet every plan also carried costs.  A blockade would take months, at least; and the ships enforcing it would be subject to kamikaze attack.  Intelligence estimated an available suicide force of 3000. Attacking from the air did not carry enormous risk; Japan had little ability to defend itself from these attacks.  But thus far, air attacks on Japan had not forced the government to capitulate—and it was not clear that they ever would.  The major cities had already been pounded; smaller cities had also been hit.  Increasingly it looked as though only a land invasion would force the Japanese to surrender.

A land invasion, however, carried the greatest costs.  Allied casualty estimates ranged up to one million; the first phase alone, an attack on Kyushu, would probably cost close to 100,000 lives.  These need not have all been American lives.  The Soviets had promised to assist the United States now that the Red Army was no longer tied down in Europe.  But American policymakers feared inviting Soviet troops into Japan and consequently into post-war decisions about Japan. 

Nevertheless, a land invasion seemed the only real option—and it was simply too costly to reject Soviet help.  Therefore, a joint invasion was schedule for November.  

Everything changed, however, with the successful testing of the atomic bomb in July 1945. America’s new president, Harry Truman, now had another, seemingly better option avoiding a prolonged blockade, devastating but ultimately ineffective conventional air raids, or a horribly costly land invasion. And there would be no Soviet troops in Japan.

On 6 August, the Enola Gay, a B-29 bomber flew out of Tinian, one of the Mariana Islands.  She was accompanied by two other planes charged with gathering scientific data on the visible effects of the first atomic bomb. Their target was Hiroshima. The manufacturing city served as supply depot for military goods.  Perhaps just as important given the scientific questions on the table, it was one of the few “military” targets relatively undamaged by previous bombing.

The city’s air raid alarms drew many of Hiroshima’s 300,000 people into the streets when they sounded.  Many were still in the streets when the bomb detonated at about 1900 feet.  An estimated 45,000 people died immediately; another 20,000 died in the next few months.

Two days later, 8 August, the Soviet Union declared war on Japan and invaded Manchuria, rapidly overwhelming the Japanese forces assigned to protect this piece of China that Japan had invaded in 1931.

Three days later, 9 August, a second atomic bomb was dropped—this time on Nagasaki.

Finally, on 10 August, the Japanese cabinet offered to surrender, asking only that the emperor be allowed to retain his throne.  Believing that the emperor’s presence might temper the social and political chaos that the end of the war could bring, the Allies agreed to this condition. On 14 August, the surrender terms were formally accepted by both sides.  The war against Japan was over.