As if eastern Congo had not already suffered enough, seven years ago Nature dealt it a stunning blow. The volcano whose blue-green bulk looms above the dusty, lakeside city of Goma, Mount Nyiragongo, erupted, sending a smoking river of lava several hundred yards wide through the center of town and sizzling into the waters of Lake Kivu. More than 10,000 homes were engulfed. Parts of the city, which is packed with displaced people, are still covered by a layer of purplish rock up to twelve feet thick.

Far greater destruction has come from more than a decade of a bewilderingly complex civil war in which millions have died. First, neighboring Uganda and Rwanda supported a rebel force under Laurent Kabila that overthrew longtime dictator Mobutu Sese Seko in 1997. Soon after, Kabila fell out with his backers, and later Uganda and Rwanda fell out with each other. Before long, they and five other nearby nations had troops on Congo’s soil, in alliance either with the shaky national government in Kinshasa or with a mushrooming number of rival ethnic warlords, particularly here in the mineral-rich east. Those foreign soldiers are almost all gone now, but some fighting between the government and remaining rebel groups continues. For two weeks in June, I had the chance to observe the war’s effects, with the best of possible traveling companions: Anneke Van Woudenberg, senior researcher for Human Rights Watch, whose reports have been an authoritative source of information on the country for years.

No one has been harder hit than Congo’s women, for almost all the warring factions have used rape as a calculated method of sowing terror. An hour and a half southwest of Goma on bone-jolting roads stand several low buildings of planks and adobe; small bleating goats wander about and a cooking fire burns on one dirt floor. There is no electricity. A sign reads Maison d’Écoute (Listening House). The office of the forty-two-year-old director, whom I will call Rebecca Kamate, extends from the side of one of the buildings; its other three walls are of thin green tarpaulin with a UNICEF emblem, through which daylight filters. The floor is gravel. Kamate pulls out a hand-written ledger to show to Anneke, her colleague Ida Sawyer, and me. Ruled columns spread across the page: date, name, age of the victim, and details—almost all are gang rapes, by three to five armed men. Since the center started, it has registered 5,973 cases of rape. The ages of the victims just since January range from two to sixty-five. On the ledger’s most recent page, the perpetrators listed include three different armed rebel groups—plus the Congolese national army.

“What pushed me into this work,” says Kamate, speaking softly in…