internecine ˌin-tər-ˈne-ˌsēn adjective
1. (of conflict) within a group or organization
2. characterized by bloodshed and carnage for both sides
The word internecine has appeared in 30 articles on NYTimes.com in the past year, including on May 10 in “South Africa’s Elections: A Weakened A.N.C. Clings to Victory” by Norimitsu Onishi:
President Cyril Ramaphosa had hoped that a decisive victory would hand him a popular mandate to carry out far-reaching reforms. But the results from Wednesday’s election — though largely positive given a stagnant economy and the relentless revelations of corruption in the party — were unlikely to quell powerful party rivals, political analysts said.
… For both Mr. Ramaphosa’s allies and rivals in the party, one of the most consequential questions focused on whether a Ramaphosa-led African National Congress would outperform the party under Mr. Zuma. The results would embolden one side or another in the continuing internecine battles.