(Newsweek) – It was just before dark, and Charles was pulling weeds with his father in South Sudan’s Western Equatoria state when roughly a dozen armed rebels appeared, demanding he join their ranks. Charles was terrified. His father tried to intervene, but he was outnumbered. That night, Charles, whose name has been changed to protect his identity, was separated from his father and forced to become a soldier. He was just 13 years old. It’s been three years since the beginning of South Sudan’s civil war, and the consequences have been devastating. Rebels and government forces have conscripted more than 17,000 children to fight, according to UNICEF, in a conflict between supporters of President Salva Kiir and those of former Vice President Riek Machar. The war has already killed tens of thousands of civilians and displaced more than 3 million people. Both sides have been accused of killings and mass rapes, but a recent U.N. report placed most of the blame on the government’s side.