A massacre is the deliberate slaughter of members of one group by one or more members of another more powerful group. A massacre may be indiscriminate or highly methodical in application. A massacre is a single event, though it may occur during the course of an extended military campaign or war. A massacre is separate from a battle (an event in which opposing sides fight), but may follow in its immediate aftermath, when one side has surrendered or lost the ability to fight, yet the victors persist in killing their opponents.
