The moral lesson of Hiroshima:
BIG BOMBS END WARS!
AND...kill the attacker when attacked. Do it by the most self-preserving way.
and there is a lesson in this excellent article that applies directly to our Iraqi mission today - that not destroying vermin such as Al-Sadr, not ruthlessly closing down the iranian proxy assistance, means these scum will live to strike us again in the future.
Tehran delenda est.