During the night of August 5th, there were a lot of signs that an attack on Hiroshima was imminent. Waves of bombers were attacking nearby cities to the west, in the Yamaguchi Prefecture: Ube, Hikari, and Kudamatsu. After Fukuyama (on the other side of Hiroshima from Ube) was firebombed, the air-raid alarms began to sound in Hiroshima, just after midnight, and continued for the next couple hours, disrupting the sleep of anyone living in the city center.