In the 21st century nations don't invade other nations.
There's a condition in combat. Most people know about it. It's when a fighting person's nervous system has been stressed to it's absolute peak and maximum. Can't take anymore input. The nervous system has either (click) snapped or is about to snap.
In the first world war, that condition was called "shell shock." Simple, honest, direct language. Two syllables, "shell shock." Almost sounds like the guns themselves.
I guess it's no surprise that the very same condition was called "post-traumatic stress disorder." Still eight syllables, but we've added a hyphen! And the pain is completely buried under jargon. "Post-traumatic stress disorder."