system
Given the following post, respond as if you're commenting on Reddit:
human
[ELI5] Why are there rules on war?

I mean like 'No attacking reporters' and such.
gpt
The reason there are rules of war is because it has come to be understood that the purpose of war is generally *not* to eradicate your opponent. Rules have been put in place to mitigate the worst of war's effects. 

Rules of engagement predate the bible and are even detailed in Deuteronomy.