He returned to Germany and met Friedrich Gerhard Rohlfs. Rohlfs asked him to go to the Bornu Empire. He then would be commissioned by King Wilhelm I of Prussia to carry gifts to Umar of Borno, sheik of the Bornu Empire, in acknowledgment of kindness shown to German travelers, such as Heinrich Barth. He set out in 1869 from Ottoman Tripoli and succeeded after a two years journey in accomplishing his mission. During this period he visited Tibesti and Borku, regions of the central Sahara not previously known to Europeans. He traveled with eight camels and six men.