There were leaflet campaigns before many large aerial bombardments of Japan in World War II, not just the nuclear bombardments.

Up to the time of the Hiroshima attack, these leaflets were fairly

generic: Expect massive bombing in these cities in the next day or so. Get out in time, save yourself -- that sort of thing.

Right after the Hiroshima attack, there was another leaflet campaign that informed people that a new type of extremely destructive bomb had been used, and urged them to ask their leaders about Hiroshima. I have read that there was a considerable effort made to confiscate these leaflets.

There were leaflets specially intended for the Kokura attack (which was aborted and shifted to Negasaki). Because of a scheduling mistake, they were dropped after the Negasaki attack.

During the later stages of World War II, Japanese civilians did not have a great deal of freedom to simply come and go as they pleased. I suspect these leaflet campaigns accomplished very little. Most of the citizens of targeted cities were probably unable to do much to save themselves.

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