Precisely this. There is no real winner in war (I'm a US Army Veteran of OIF II circa 2003-2004), only one side that might lose less. Taking a life breaks many people, even trained infantry. Look at all of the veteran suicides due to PTSD from war as proof of this.

Once someone on either side has been killed in war, both sides permanently lose. There are no take-backs, only damaged soldiers on both sides and casualties.