Internecine

[Sarah]

Involving, or accompanied by, mutual slaughter; mutuallydestructive.Internecine quarrels, horrible tumults, stain the streets with blood.Motley.

[Sarah]

pronounced IN-ter-NEE-sin. It comes from the Latin: inter (between, among) and necare (to kill). It means a conflict destructive to both sides, or very bloody. We do tend to use it to describe civil wars.