After visiting London to study British principles of colonization, Peters founded the Society for German Colonization in 1884 and later that year, in the Usambara Mountains area of present-day northeastern Tanzania, made a number of contracts with chiefs who surrendered their territories to him. He later helped to extend the German sphere of influence and established the German East Africa Company, which obtained an imperial charter in 1885. He reached Uganda in 1890 and concluded a treaty with the king, but without the support of the German government. This treaty was declared void, for an agreement had been reached between Germany and Great Britain by which Uganda was left in the British sphere. He became imperial high commissioner for Kilimanjaro in 1891 but was deprived of his commission in 1897 for misuse of official power in his treatment of the Africans. From 1899 to 1901 he explored regions along the Zambezi River with a view to commercial exploitation and described his discovery of ancient cities and gold mines in Im Goldland des Altertums (1902; The Eldorado of the Ancients). He also published Die deutsche Emin-Pascha Expedition (1891; New Light on Dark Africa), among other works.