Empathy disappears in other contexts too. The military in particular selectively damages empathy in people, because you can’t have empathy for someone you have to shoot. That’s not to say that soldiers are heartless bastards; they’re not, as seen by countless humanitarian gestures they make, but at the same time they have to be able to turn it off like a switch, and the result is that even when they feel it, it’s never quite the same.
No empathy for enemy combatants.
Normal empathy for non-combatants.
Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)