Christianity has been a driving force in the process of nation building in South Sudan. Focusing on the city of Wau (Bahr el-Ghazal), this study considers the impact of Catholicism. Starting with the legacy of the Marchand Mission, which originated in the modern city of Wau, Catholicism expanded initially through the work of the Comboni Mission. Following the horrors of the first civil war (1955–1972), Wau became a diocese in 1974, and the Catholic Church established a major medical center there headed by a white missionary, Father Hubert Barbier. In spite of the destruction wrought by the second civil war (1983–2005), the work continued against the backdrop of an international awareness-raising campaign led by Father Barbier in France.