You are rather dense... Through much of World War II, Allied bombers would sometimes drop leaflets warning of impending bombing of a city. The leaflets often told civilians to evacuate, and sometimes encouraged them to push their leaders to surrender. In August 1945, leaflets were dropped on several Japanese cities (including, supposedly, Hiroshima and Nagasaki). The first round, known as the "LeMay leaflets," were distributed before the bombing of Hiroshima. These leaflets did not directly reference the atomic bomb, and it is unclear whether they were used to warn citizens of Hiroshima and Nagasaki specifically. The second round features a picture of a mushroom cloud and a message about the Soviet invasion (which commenced on August 9). The historical record is unclear, but it seems as though these leaflets did not make it to Nagasaki until after it, too, had been hit by an atomic bomb. Later leaflets informed the Japanese populace about their government's surrender before the emperor's official announcement. http://www.atomicheritage.org/key-documents/warning-leaflets