Nonsense. The US dropped the world's first atomic bomb on Hiroshima, a military base [accuracy.org]. That was because they wished in this first attack to avoid, insofar as possible, the killing of civilians.
Oh, bullshit. Hiroshima was no more a "military base" than were any number of American cities.
A total of some 40,000 military personnel were present in the city. The rest of the approximately 350,000 population were civilians.
The number killed was very approximately 100,000. It is plain that not even the majority could possibly have been military personnel.