The White Fathers missionaries had established posts in the northwest of Tanganyika that formed an obstacle to Arab incursions into the Maniema region, protected by Captain Léopold Louis Joubert, a former Papal Zouave.[15] Rumaliza tolerated the foundation of the missions at Mulwewa in 1880 and Kibanga in 1883, but would not allow establishment of a station at Ujiji.[12] In May 1890 a group of Arabs came close to attacking the White Fathers mission at Mpala on the west shore of Lake Tanganyika, and only withdrew after a storm destroyed a number of their supply boats. Before leaving they confirmed that Rumaliza had given orders to them not to harm the missionaries.[16] In September 1890 the White Fathers missionaries Léonce Bridoux and Francois Coulbois visited Ujiji, where they found Rumaliza and Tippu Tip. The two slavers were friendly, and Rumaliza was anxious that the missionaries gave a good report of him to Emin Pasha, who was expected at Ujiji.