[bombcar]

The atomic bomb was “shock and awe” - the implication was that the US would just continue to delete cities one by one easily until Japan surrendered. The destruction was comparable or even less than other firebombing raids but done with one plane.

[defrost]

At the time ... the two atomic bomb tests were the first live theatre tests of two aerial bomb designs only one of which had been previously tested in a controlled tower detonation (Trinity).

The two tests (Hiroshima & Nagasaki) were squeezed into an long ongoing campaign that had already "deleted" 72 cities .. at a time when the conventional campaign was already running out of good targets.

The atomic bombs had been developed at great expense to use on Germany and were not yet ready to test when Germany surrended.

Those military at the head of the Manhatten Project were desperate to find live theatre test sites before Japan surrended to either the US or, god forbid, the Russians (who had advanced so far through the formerly Japanese occupied terrirory in China that Japanee surrender to Russia was considered a very real possibility at the time).

While the Project had the ability to painstakingly handcraft more bombs at a low rate (and at very very great expense), they had not yet developed the Cold War production line ability to reliably turn out hundreds more bombs.

It's well worth reading up on the thoughts of the time before the after the fact post surrender stories spun up and atomic weapon use became a key part of the Cold War zeitgeist.