A fortnight later, at the formal May 10 target meeting, Robert Oppenheimer, the chief scientist on the project, ran through the agenda. It included “height of detonation,” “gadget [bomb] jettisoning and landing,” “status of targets,” “psychological factors in target selection,” “radiological effects,” and so on. Joyce C. Stearns, a scientist representing the Air Force, named the four shortlisted targets in order of preference: Kyoto, Hiroshima, Yokohama, and Kokura. They were all “large urban areas of more than three miles in diameter;” “capable of being effectively damaged by the blast;” and “likely to be unattacked by next August.” Someone raised the possibility of bombing the emperor’s palace in Tokyo—a spectacular idea, they agreed, but militarily impractical. In any case, Tokyo had been struck from the list because it was already “rubble,” the minutes noted.

Kyoto, a large industrial city with a population of 1 million, met most of the committee’s criteria. Thousands of Japanese people and industries had moved there to escape destruction elsewhere; furthermore, stated Stearns, Kyoto’s psychological advantage as a cultural and “intellectual center” made the residents “more likely to appreciate the significance of such a weapon as the gadget.”

Hiroshima, a city of 318,000, held similar appeal. It was “an important army depot and port of embarkation,” said Stearns, situated in the middle of an urban area “of such a size that a large part of the city could be extensively damaged.” Hiroshima, the biggest of the “unattacked” targets, was surrounded by hills that were “likely to produce a focusing effect which would considerably increase the blast damage.” On top of this, the Ota River made it “not a good” incendiary target, raising the likelihood of its preservation for the atomic bomb.

The meeting barely touched on the two cities’ military attributes, if any. Kyoto, Japan’s ancient capital, had no significant military installations; however, its beautiful wooden shrines and temples recommended it, Groves had earlier said (he was not at the May 10 meeting), as both sentimental and highly combustible. Hiroshima’s port and main industrial and military districts were located outside the urban regions, to the southeast of the city.

The gentlemen unanimously agreed that the bomb should be dropped on a large urban center, the psychological impact of which should be “spectacular” to ensure “international recognition” of the new weapon.

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The Target Committee regrouped at the Pentagon on May 28 (Oppenheimer sent a representative). The members concentrated on the aiming points within the targeted cities. The plane carrying the atomic bomb “should avoid trying to pinpoint” military or industrial installations because they were “small, spread on fringes of city and quite dispersed.” Instead, aircrews should “endeavor to place … [the] gadget in [the] center of selected city.” They were quite explicit about this: The plane should target the heart of a major city. One reason was that the aircraft had to release the bomb from a great height—some 30,000 feet—to escape the shock wave and avoid the radioactive cloud; that limited the target to large urban areas easily visible from the air.