Natural selection is the change of a species traits and characteristics over time to adapt to its environment. Over a period of time, the species will change and evolve because of its changing traits to adapt.
I don't know what your options were, but here are some stated purposes of war (stated formally or informally):
-removal of Saddam Hussein from the power
-being able to check for any existing biological, chemical or nuclear weapons that Hussein might have
-introducing democracy to Iraq:
They basically control where the United Nations sends troops and who to declare war on
