Pentagon, Washington, D.C. May 31, 1945

On this date in 1945 a special group met in the Pen­ta­gon to search for an alter­na­tive to dropping the atomic bomb on Japan. The group had been called into exis­tence by the new Ameri­can presi­dent, Harry S. Tru­man. Neither Truman nor any­one else in the room knew what kind of damage the still-untested weapon might do.

What the planners thought they knew, how­ever, espe­cially as the fero­city of Japa­nese resis­tance on Oki­nawa became clear, was this: the tally of U.S. and Japa­nese war dead would boggle the mind. As it turned out, at the end of the Oki­nawa cam­paign (April 1 to June 21, 1945) the dead numbered 12,500 Amer­i­cans and 110,000 Japa­nese; the loss in tanks, ships (36 sunk and 368 damaged), air­craft, and other materiel was so severe three-quarters of the way through the cam­paign that poli­tical and mili­tary leaders alike were increas­ingly wary of the end­game costs. The inva­sion of the Japa­nese main islands, or Home Islands, set to begin in November 1945 and end the next April, was pre­dicted to cost as many as one million Allied lives, to say nothing of other losses on both sides. (Though the pre­dic­tion came out after the war had ended, some analysts believed it was too low.)

Six weeks later, on July 16, a huge pre­dawn explo­sion in the New Mexico desert settled the issue. “We have dis­covered the most terri­ble bomb in the his­tory of the world,” Truman wrote in his diary on July 25 while attending the victors’ Potsdam Con­fer­ence out­side the former Nazi capital of Berlin. Three days later, the Japa­nese cabi­net under 77‑year-old Adm. Kantarō Suzuki, having failed to over­come the resis­tance of the over­whelming major­ity of Japa­nese mili­tary offi­cers to the Allies’ final demand for their coun­try’s uncon­di­tional sur­render—the July 26 Pots­dam Dec­la­ra­tion—ignored the ulti­ma­tum, despite its expli­cit warning that the only alter­na­tive would be “prompt and utter destruc­tion.” (The word used in the Japa­nese press for the cabi­net’s non-response, moku­satsu, means “to kill it with silence” (as in silent con­tempt), though one Japa­nese-run news­paper, the Hong Kong News, broke press ranks to blast the Pots­dam Dec­la­ra­tion as a piece of unqual­i­fied impu­dence.) Days before, Truman had con­fided to Soviet dicta­tor Joseph Stalin, who was not offic­i­ally a party to the Pots­dam Declara­tion because his country had not yet declared war on Japan, that the U.S. was pre­pared to use its dooms­day weapon “very soon unless Japan surrenders.”

But the president was concerned about where to use it. Neither Tokyo, or what was left of it, nor the ancient Japa­nese capital of Kyoto was an appro­pri­ate tar­get for nuclear destruc­tion. Truman ordered the Sec­re­tary of War to find tar­gets with heavy con­cen­tra­tions of mili­tary person­nel and to issue warning state­ments asking the Japa­nese to sur­render to save lives. “I’m sure they will not do that,” he wrote in his private papers, “but we will have given them the chance.”

A short list of suitable targets was devised. Within two weeks Hiro­shima and Naga­saki lay in ruins, not to be the last devas­tated Japa­nese city if the coun­try didn’t surrender, Truman pro­mised its leaders. The most destruc­tive bomb in his­tory killed 120,000 people (mostly civil­ians) out­right, brought World War II to an end, and marked the begin­ning of the atomic age. Amer­i­cans’ over­whelming desire to avoid further U.S. mili­tary casual­ties, com­bined with a desire for ven­geance against Shōwa Emperor Hiro­hito, his war­lords, and his sub­jects, left the major­ity of the coun­try indif­ferent to killing on an atomic scale, at least initially.

Hiroshima, August 1945

U.S. Army poster 1945Atomic bombing of Hiroshima and Nagasaki: Mission map for the atomic bombings, August 1945

Left: U.S. Army poster prepares the Amer­i­can pub­lic for the in­va­sion of Japan after ending war with Germany and Italy. Presi­dent Truman’s mili­tary chief of staff, Army Gen. George Marshall, esti­mated that the U.S. armed forces would suffer up to one million casual­ties over the next two years trying to take the Japa­nese Home Islands by conven­tional force. Truman was unwilling to sell terms like these to the Amer­i­can public, in spite of likely becoming the object of condem­na­tion in some quarters for ordering the atomic destruction of Japan.

Right: Mission map for the atomic bombings of Hiro­shima and Naga­saki, August 6 (Enola Gay) and August 9, 1945 (Bocks­car). Kokura, on the north­ern tip of the south­ern island of Kyūshū, appears on this map because it was the origi­nal tar­get for August 9. Weather obscured visi­bility over Kokura, so Nagasaki, also on Kyūshū, was chosen instead.

Atomic bombing of Hiroshima and Nagasaki: Warning leaflet dropped over Japanese cities, August 1945Atomic bombing of Hiroshima and Nagasaki: Atomic cloud over Hiroshima, August 6, 1945

Left: Front and back of leaf­lets urging Japan’s quick sur­render were dropped over the coun­try by the 509th Com­po­site Group, a group that com­prised B‑29 bombers and trans­port air­craft. The 509th was a component of the U.S. Man­hat­tan Pro­ject under the com­mand of Lt. Col. Paul W. Tibbets, Jr. At 2:45 a.m. on August 6, 1945, the Enola Gay departed Tinian in the Mari­ana Islands for Hiro­shima with Tibbets at the con­trols. Flight distance from Tinian to Hiro­shima was just under 1,600 miles, so it took the Enola Gay six hours to reach its desti­nation. The atomic bomb, code­named “Little Boy,” was dropped above the resi­den­tial and com­mer­cial center of the city at 8:15 a.m. local time. (According to some his­to­rians the non­military aspect of ground zero was intended to mag­nify the shock effect on the Japa­nese public and leader­ship in Tokyo.) Tibbets reported that Hiro­shima was covered with a tall mushroom cloud after the bomb was dropped.

Right: Atomic cloud over Hiroshima, August 6, 1945, 8:45 a.m. This photo­graph was found in 2013 at Hon­kawa Ele­men­tary School (now a peace museum) and is believed to have been taken 6 miles east of ground zero (aka hypo­center) about 30 minutes after deto­na­tion. Samples of beach sand four miles and more from Hiro­shima’s hypo­center reveal round, fine glassy shards that were once buildings and other urban-built struc­tures that were swept up in the nuclear blast and fused in incred­i­ble heat before cooling and raining down to earth. Esti­mated to weigh in aggre­gate thou­sands of tons, these tiny spher­u­lar par­ti­cles of the vanished city of Hiro­shima, nick­named “Hiro­shi­maites,” consti­tute up to 2.5 per­cent of the regular sand along the beaches of Hiroshima Bay.

Atomic bombing of Hiroshima and Nagasaki: Hiroshima, September 1945. Genbaku (A-Bomb) Dome in backgroundAtomic bombing of Hiroshima and Nagasaki: Hiroshima, September 1945

Left: Hiroshima, the once-vibrant city of over a quarter mil­lion men, women, and chil­dren, Septem­ber 1945. In the back­ground the Genba­ku (A-Bomb) Dome, the only struc­ture left standing near ground zero. The building, at the time serving as the Hiro­shima Prefec­tural Indus­trial Pro­mo­tion Hall, later became a part of the Hiro­shima Peace Memo­rial Park, which was desig­nated a UNESCO World Heritage Site in 1996.

Right: Hiroshima, September 1945. Japa­nese off­icials deter­mined that 69 per­cent of Hiro­shima’s buildings were de­stroyed and another 6–7 per­cent were damaged. Out of some 70,000–80,000 peo­ple killed imme­di­ately in the blast and ensuing fire­storm (a conser­va­tive figure), 20,000 were sol­diers, a ratio of mili­tary to civil­ian dead Pre­si­dent Truman had urged (the higher the better) in his directive to Secretary of War Henry L. Simpson. Need­less to say the final tally of Hiro­shima’s dead must include the tens of thou­sands who later succumbed to their horrific injuries and those who perished months and years later from radiation-related sicknesses.

Hiroshima: Dropping the Bomb, a BBC Production