"I had a white companion"

During his own overland journey from Matadi to Kinshasa, Conrad was accompanied by Prosper-Félix-Joseph Harou, a Belgian 'sous-officier' (uncommissioned or minor officer) of the Société Anonyme Belge pour le Commerce du Haut-Congo. Harou had arrived from Europe on the same ship as Conrad. Like Marlow's companion, he became stricken with fever and had to be carried in a hammock.

Harou's older brother, Victor, had accompanied Stanley on his 1879-82 Congo expedition, and had helped establish the settlement of Vivi, the first important post on the Congo River.