The fact is some people just need to be killed.
Dec 1835:
The Maori decide to celebrate the holiday season by visiting the Moriori on the Chatham Islands. They announce the Moriori are now their slaves and kill a few who object. The Moriori react by having a council meeting where they decide not to fight back but to offer peace, friendship and division of resources. Before they can make this generous offer the Maori attack kill hundreds of Moriori, many of whom they cook and eat, and enslave the rest.
Moral: Pacifists are an important source of protein in the warrior diet.