Jim, most of us here, including you, are too young to remember when "friendly fire" entered the language. I have seen the phrase in documents dating back to the Great War, when it usually meant artillery rounds that landed on the wrong targets.

You don't like "complicated"? It's the best I could do without writing a long paragraph. All wars are complicated, of course, but some are more complicated than others. Wars of insurgency are full of cross-cutting loyalties and people changing sides, which makes them "interesting" for historians and bloody difficult for the people who have to fight them and do so under the unremitting gaze of the backseat drivers of the news media.

Which, of course, is where the euphemisms come from. Our ancestors could say that the role of infantry is "to close with and destroy the enemy", but God forbid that a senior commander in a "good" army of the 21st century ever use such blunt terms where civilians can hear him.