Nigeria, Feb. 6 -- I remember one of my trips to Kaiama with a group of friends a few years ago, at the early stages of the Boko Haram crisis. As we drove through the vast Borgu Game Reserve, endless forests, deep isolation, and historically bad roads, a troubling thought crossed my mind: if Boko Haram ever reached this place, it would easily make it a home. The terrain, the remoteness, and the thin presence of the state created exactly the conditions in which insurgent groups flourish. At the time, it felt like an abstract fear. After the massacre at Kasuwar Dare, Borno Local Government, and now Woro, it feels disturbingly real.

For more than six hours, from about 5:30 p.m. to midnight, armed groups descended on the rural community of W...