Data from: Lethal conflict after group fission in wild chimpanzees

Territorial conflicts in animals inform aspects of human warfare, but
civil war, with its shifting group identities, appears to be uniquely
human. We report a rare, permanent fission in the largest-known group of
wild chimpanzees (Pan troglodytes). Using 30 years of behavioral
observations and network analyses, we identify an abrupt transition from
cohesion to polarization in 2015 and the emergence of two distinct groups
by 2018. Over the next seven years, members of one of the splinter groups
made 24 attacks, killing at least seven mature males and 17 infants in the
other group. We provide the data and code used to analyze chimpanzee
social networks. We provide the data and the code for other analyses,
including figures on changes in group size, social networks, and
mortality.