Members of a Taliban militant group, seeking revenge on the Pakistani military for their losses, charged into a school where many students were children of military officers. The military responded and the Taliban members were eventually tracked down and killed. But the price was 141 lives. Now the Pakistani military is planning larger-scale assaults on the militants.
We've seen this far too often. Everywhere. Group A kills a few of Group B. Group B sends someone to shoot an entire family belonging to Group A. Group A blows up a place of worship that's frequented by many members of Group B. And so on. With a higher body count each time one of these "revenge" attacks occurs.
It won't stop until either side, or possibly both, has been destroyed.
Those who have the good fortune to live in a country that is not at war or otherwise in conflict with another state might believe that they have peace. However conflict invariably affects a greater area than just the originating groups, as militants expand their territory and refugees flee the fighting. Everyone is at risk.
For the last century there hasn't been a time where there has not been conflict on the planet somewhere, with the exception of a short period following the end of World War II. At this time of the year we might sing and pray about peace on Earth, but given the varying religions, social structures, and availability of resources, true world peace is sadly unattainable.