Disaster struck the Niger and the Congo expeditions alike, though it took somewhat different forms in each case. The Congo River’s cataracts and the region’s diseases posed the most serious obstacles to the latter expedition, though it also ran out of the trade goods needed to hire guides and porters. For the Niger expedition, the rapid reduction in the number of pack animals at its disposal created serious logistical problems, which were amplified by the power the ruler of Futa Jallon increasingly wielded over its operations. Although disease also contributed to the expedition’s difficulties, the most prominent factor in its failure was political; African authorities blocked its passage because they saw it as a threat to their religious, strategic, and economic interests. By contrast, the Congo expedition reassured Boma’s rulers about its intentions, easing its access to the river. Both expeditions’ experiences demonstrated that African polities and peoples shaped their outcomes in important ways.