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 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 home islands, set to begin in November 1945 and end the next April, was esti­mated to cost as many as one mil­lion Allied lives, to say nothing of other losses on both sides. 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. Three days later, the Japa­nese cabi­net rejected a final demand for un­con­di­tional sur­render, the Pots­dam Declara­tion (issued July 26, 1945), de­spite an expli­cit warning that the only alter­na­tive would be “prompt and utter destruc­tion.” Truman told Soviet dicta­tor Joseph Stalin two days earlier that the U.S. was pre­pared to use the 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 was 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 if the coun­try didn’t surrender, Truman pro­mised Japa­nese leaders. The most de­struc­tive bomb in his­tory killed 120,000 people, brought World War II to an end, and marked the beginning of the atomic age.

Hiroshima, August 1945

U.S. Army poster 1945Mission 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.

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.

 Warning leaflet dropped over Japanese cities, August 1945Atomic 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. Tinian was approx­i­mately 2,000 miles away from Japan, so it took six hours to reach Hiros­hima. The atomic bomb, codenamed “Little Boy,” was dropped over the city at 8:15 local time. 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 about 30 minutes after detonation.

Hiroshima, September 1945. Genbaku (A-Bomb) Dome in backgroundHiroshima, September 1945

Left: Hiroshima, 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, 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.

Hiroshima: The Aftermath