In 1886, while Tippu Tip was in Zanzibar, a dispute arose between a Congo Free State fort at Stanley Falls, led by Tip, and a smaller, nearby fort led by Walter Deane and Dubois. Tip's men at the Stanley Falls fort alleged that Deane had stolen a slave woman from an Arab officer there. Deane asserted that the girl had fled after being badly beaten by her master, and that he had only offered her refuge. Tip's men attacked the fort and after a four-day siege, the defenders ran out of ammunition and fled, abandoning the fort. The Free State made no counterattack, and Tip began to move more men into the Congo, including several Arab slave captains and also some Congolese leaders, such as Gongo Lutete.