Santa Barbara, California, June 3 -- The Rev. Paul Lueth Kat Deng had spent years helping people flee war.

Since 2008, the South Sudanese pastor had worked in refugee camps, including in Sudan's Darfur region during the genocide there, supporting displaced families with food, prayer, and medical aid. He had seen children wounded by conflict before. But last year, the crisis took a personal turn.

His teenage nephew, Ajak, told him he had been abducted and forced to fight as a child soldier in Sudan by paramilitary forces. The boy eventually escaped, but not before being shot multiple times in the leg.

By the time Ajak reached medical care in South Sudan, doctors feared the leg might need to be amputated unless he received emergency surg...