Is perhaps the most confusing place ever tread by man.
You're a pilot in an F-16, A-10, Apache Gunship, commander of an M1-A1 or Standing Sentry, it's the middle of the night. The position you have been assigned is known to have hostiles in it, you see Arms fire apparently directed at you. You have 10 seconds to make a decision, and in the back of your mind you know it may be the last decision you ever make.

Sadly, sometimes it is the wrong decision.

The modern battlefield moves fast. I have come to the conclusion that we may be at the limits of most soldiers ability to keep up. The fog of war is now a solid blanket.

Murphy's War Law's,#146 Friendly fire - isn't.
But it happens, and to be honest, a lot less than it used to.