Erhardt was dispatched by the Church Mission Society to East Africa. On 10 June 1849 Erhardt and John Wagner arrived at the
Rabbai Mpia mission station near
Mombasa, where they joined
Johann Ludwig Krapf and
Johannes Rebmann. However, Wagner died on 1 August 1849. In the spring of 1850, Erhardt and Krapf travelled by dhow down the East African coast from Mombasa. The boat was small and food was scarce, poor quality and difficult to prepare due to the rain. However, they collected much information about the interior. Erhardt and Krapf went via
Tanga,
Kilwa,
Lindi and
Mikindani to
Cape Delgado. The two missionaries, the first Europeans to investigate the coast in such detail, went unarmed and with few escorts, and were generally given a good reception by the Arabs, Swahilis, and local people they met. They mapped the
Pangani River's mouth, the delta of the
Rufiji River and the
Ruvuma River. After the voyage, the two returned to the mission station, and in 1851 Krapf left for Europe to recuperate. In September 1853, Erhardt visited Vugha in the
Usambara Mountains, capital of the
Shambaa ruler
Kimweri ye Nyumbai, where he saw two witches brought in and executed. Erhardt recorded the repulse of a
Maasai raid at
Mazinde by an allied army of Shambaa under Semboja, Kimweri's son, and of Wazigua, Parakuyo and "Arabs" (most likely
Swahili). Erhardt's journey took from 9 August 1853 to December 1853, and he spent three months with the king. dated June 1856, based on the Erhard and Reibmann sketch and on a map by
August Heinrich Petermann Erhadt spent six months in Tanga in 1854, where he studied the
Shambala language. At Tanga, where caravans assembled before leaving for the interior, he learned of Ukerewe (
Lake Victoria),
Lake Tanganyika and
Lake Nyasa, and heard of the city of
Ujiji. However, he was told by ivory traders that the great inland "
Sea of Uniamesi" was just a westward extension of Lake Nyasa, reaching close to the mountains that formed the spine of the continent. Erhardt was struck by the fact that various travellers who had gone inland from different points on the coast had all come to an inland sea, and made a map based on available information, including the findings of his fellow missionaries Krapf and Rebmann. In November 1854 while talking about the problem to Rebmann, "at one and the same moment, the problem flashed on both of us solved by the simple supposition that where geographical hypothesis had hitherto supposed an enormous mountain-land, we must now look for an enormous valley and an inland sea." On the map that he and Rebmann drew the three lakes are shown as one very large S-shaped lake. ==Later career==